Bài Viết BGP

Bi Vit BGP

Tc gi: L Vn Cng I Autonomous Systems

1. Tng Quan v Autonomous System - Autonomous system (as) : Mt AS l mt nhm cc router cng chia s mt chnh sch v hot ng trong cng mt min nht inh(domain) - Mi AS c mt s nhn din v c cung cp bi mt nh cung cp AS (internet registry) hoc nh cung cp dch v s ny t 1 -> 65,535. Khong t 64,512 cho n 65,535 c dnh cho cc AS Private s dng. 2. AS c mt kt ni duy nht ra AS khc(SingleHomed AS) - Nu mt AS c duy nht mt kt ni ra mng bn ngoi, th n c xem l kt ni n (single).

3. AS c nhiu kt ni ra mng bn ngoi(Multihomed AS MA) - Mt AS l mt MA khi n c nhiu hn mt kt ni ra mng bn ngoi. Mt MA khi n c kt ni n internet c th n mt hay nhiu nh cung cp. -AS ny c th l Transit hoc Non-Transit AS > Transit : AS ny s chuyn tip thng tin t nh cung cp ny sang nh cung cp khc H1

> Non-Transit: AS ny khng chuyn tip thng tin gia hai nh cung cp khc nhau H2

4. Khi no khng nn s dng BGP trong mt AS Khi ch c duy nht mt kt ni n internet hay n mt AS khc Khi chnh sch v nh tuyn cc Route khng cn thit trong mt AS Router BGP khng RAM hay kh nng x l qun l cc cp nht Nh qun tr t am hiu v lc(filter) cc tuyn(route) v qu trnh la chn ng dn

(path) Bng thng thp gia cc AS

Hot ng c bn cua BGP Cp nht bng nh tuyn Chc nng ca BGP l trao i thng tin nh tuyn gia cc AS v m bo la chn tuyn thng sut(loop free path LFP) BGP cp nht s dng TCP cng 179. TCP l mt kt ni m phi c s tho thun trc khi cp nht c chuyn i i, do BGP tha k tnh tin cy, kt ni c nh hng ca TCP. m bo la chn tuyn khng loop(LFP ) th , BGP xy dng mt biu ca cc AS da trn thng tin trao i gia cc BGP lng ging. BGP xem ton b mng nh l mt biu hay mt cy. Kt ni gia bt k hai AS no cng c nh ngha l ng Path.

H1

BGP lng ging khi hai BGP router thit lp mt kt ni TCP, c gi l lng ging (neighbor) hay ngang hng (peer), mi router chy BGP c gi l BGP speaker. Peer router trao i thng tin bng nhiu bn tin m v xc nhn cc thng s kt ni, nh version ca BGP dang c s dng, nu c bt k s khng ng no gia cc peer th, thng tin cnh bo (notification) c gi

ra gia cc peer. Khi quan h lng ging c thit lp, th chng s trao i cc thng tin v BGP route. Sau khi vic trao i thng tin c khi tao xong, th cc cp nht thnh phn(incemental update) c gi i khi c thng tin thay i trong mng ch khng truyn ton b bng nh tuyn. Peer truyn cc destinations m n c th thy c bng cc thng tin cp nht cho cc Peer ca n. Thng tin v kh nng n cc destination c trao i, chng hn khi mt route tr nn khng n c th BGP s cnh bo cho lng ging ca n v thng tin ny bng thu hi(withdrawing) cc route sai v thay i bng nh tuyn mi. H2

Nu khng c thng tin nh tuyn no c trao i vi cc peer, th BGP speaker s truyn mt cch c chu k cc bn tin keepalive cho nhau duy tr kt ni. Gi Keepalive(19 byte) c gi i trong vng 60 giy theo mc inh v ta c the thay i n c.

Cc loi bn tin ca BGP Cc loi bn tin khc nhau thc hin mt chc nng trong hot ng ca BGP. Mi bn tin mang mt thng tin tiu .Thng tin trong tiu ch gm 3 trng: 16 byte Maker, 2 byte Length, v 1 byte Type. Trng Maker c s dng hoc xc thc(authentication) hoc kim tra ng b gia cc peer. Trng Length : ch ra chiu di tng cng ca bn tin, gm c phn tiu . bn tin nh nht ca BGP l 19 bytes = 16 + 2 + 1 , v chiu di ti a l 4096 bytes. Trng Type c th c 4 gi tr t 1 -> 4. Mi ga tr ny tng ng -vi mt trong 4 loi bn tin Cc loi bn tin: Open message : bn tin ny c s dng thit lp kt ni vi cc peer, v gm c c trng cho version, ch s AS, hold time, v ID ca router. Keepalive message: bn tin ny c truyn i mt cch c chu k gia cc peers duy tr kt ni v kim tra tuyn. Nu khong thi gian truyn keepalive c cu hnh vi gi tr l 0, th s khng c thng tin keepalive c truyn di. Holdtime = 3xkeepaive. bn tin keep alive gm 19 byte tiu v khng c thng tin d liu c truyn i trong bn tin ny. Notification message : bn tin ny c s dng ch th cho router nhn bit c l c li. Bn tin ny gm mt trng cho m li c s dng cho vic khc phc v sa li. Update message: thng tin cp nht ny gm tt c cc thng tin s dung xy dng mt s LFP ca ton mng. C cc thng tin thnh phn c b trong Update message d l: NLRI, thuc tn ca Path, v thu hi route(withdraw route) Tho thun gia cc peer Qu trnh tho thun gia cc peer c thc hin qua

nhiu trng thi: c 6 trng thi ca BGP : Idle: idle l trng thi u tin ca mt kt ni BGP. BGP ch s kin bt u, n thng l khi to bi nh qun tr hoc l cc s kin (event) trong mng. Ti s kin khi to, to cc thng tin cn thit v reset li cc timer : holdtime Idle c th c chuyn v t mt trng thi khc trong trng hp c li. Connect: trong trng thi connect : BGP ch cho kt ni TCP c hon thnh. Nu kt ni TCP thnh cng, th trng thi ny c chuyn tip sang trng thi OpenSent. Nu kt ni TCP li th trng thi ny chuyn sang trng thi Acitve,v router c gng thit lp kt ni li. Nu mt kt ni m retry timer ht hn(expire) th trng thi c duy tr trangk thi Connect,th timer c reset, v kt ni TCP c khi to li. Trong trng hp s kin c khi to bi nh qun tr th trng thi chuyn v idle. Active: trong trng thi Active th BGP c gng yu cu mt peer khi to kt ni TCP. Nu thnh cng, n chuyn sang trng thi OpenSent. Nu thi gian kt ni retry timer ht han, th BGP s chuyn v trng thi Connect li. Trong khi active, th BGP vn lng nghe mt kt ni khc c khi to t peer. Trng thi c th chuyn v Idle trong trng hp c cc s kin khc, nh kt thc s kin bi h thng hay nh qun tr. OpenSent : trong trng thi ny, BGP ch mt bn tin open t peer ca n. bn tin open c kim tra tnh ng n. Trong trng hp c xy ra li, nh: version khng thch hp hay AS khng chp nhn, th h thng truyn bn tin ch bo v reset keepalive timer. Ti trng thi ny th hold time c tho thun v khong thi gian no nh hn s c chn. Nu thi gian hold time c tho thun l 0 th hold timer v keepalive timer s khng c khi tao. OpenConfirm: Trong trng thi ny, BGP ch bn tin keepalive hay bn tin ch th cnh bo. Nu mt bn tin keepalive c nhn, th trng thi ny chuyn sang trng thi Established, v lng ging tho thun hon thnh. Nu h thng nhn mt bn tin cp nht hay keepalive, th n reset holdtime, v trng thi chuyn v idle. H thng truyn mt cch c chu k cc bn tin keepalive cho peer theo tc c ci t theo keepalive timer. Trong trng hp bt k mmt s ngng kt ni TCP hay chm dt s kin, c to ra bi nh qun tr th trng thi s chuyn v trng

tha idl. Established: ay l trng thi sau cng ca s tho thun ca cc peer. BGP bt u trao i cc gi cp nht vi cc peers ca n. Nu khng phi l 0 th hold time s c reset li khi n nhn c thng tin cp nht hay bn tin keepalive. Mi gi cp nht u c kim tra li, nh trng hp li hay trng lp cc thuc tnh. Nu c li c pht hin th mt bn tin cnh bo (notification) c gi i cho Peer. Bt k bn tin cnh bo no c nhn trong khi trng thi Established lm cho BGP xo Peer dang nhn v tr v trng thi Idle. Nu Hold time ht hn, hay mt bn tin ch th ct kt ni nhn c t Peer, hay ngng s kin c nhn th h thng s tr v trng thi Idle. NLRI Thay v truyn thng tin v mt ch c th n c la Network v Subnet mask th BGP truyn NLRI, gm Prefix v chiu di ca prefix. Prefix s miu t cho dch c th n c v chiu di ca prefix l miu t cho s lng bt ca subnet mask. Ex: NLRI miu t prefix 192.168.1.0, v chiu di l 19 bit mask. Withdraw Route : Bn tin ny cung cp mt danh sc cc tuyn cp nht khng cn n c na v cn phi thu hi hay xo ra khi bng nh tuyn ca BGP. Mt bn tin cp nht khng bao gm thng tin NLRI hay cc thng tin thuc tnh th n ch c dng cho Withdraw H1

Thuc tnh ca Path Hu ht cu hnh BGP tp trung vo thuc tnh ca path. Mi tuyn c gi tr thuc tnh c nh ngha c th gm : thong tin path, route preference, next hop, v tm tt route. Nh qun tr s dng nhng

thuc tnh ny to cc chnh sch nh tuyn. Da trn cc gi tr ca thuc tnh BGP c th c cu hnh lc cc thng tin nh tuyn, cc path, hay cc ng thi khc. C cc loi thuc tnh sau: Well-know mandatory: l thuc tnh m bt buc phi tn ti trong bn tin cp nht. N phi c nhn ra bi tt c cc Peer. Nu mt thuc tnh Well-know b thiu, th mt bn tin ch th li oc to ra. iu ny m bo rng tt c cc BGP peer phi tho thun theo mt chun nht nh. Well-know discretionary: l thuc tnh c nhn ra bi tt c cc BGP peer, nhng c th hoc khng gi bn tin cp nht. Optional transitive : l thuc tnh c th hay khng c nhn ra bi tt c cc BGP peer. V th thuc tinh transitive c th chp nhn v truyn i thm ch no khng c nhn ra. Optional nontransitive: l thuc tnh m c th hoc khng nhn ra bi tt c BGP peer. Cho d nhn ra hay khng th n cng khng c truyn di cho Peer khc. H1

Cu Hnh BGP 1. C bn v cu hnh BGP

dng lnh :

- khi to qu trnh BGP ta s

AS-number

Router(config)#router bgp

- Lnh Network c s dng trong IGP nhu RIP, n xc nh cng giao tip no truyn v nhn cc cp nht. Tuy nhin vi BTP th lnh network khng nh hng n cng giao tip no m n qung b. V th network s khng thit lp quan h gia cc BGP router

Router(config)#network networknumber [mask network-mask]

Lnh network cho bit route no hc c ni b qung b i. Route ny c th l route tnh, kt ni trc tip, hoc route hc c t IGP nh(RIP, OSPF,) - router BGP thit lp quan h lng ging vi mt router khc th ta s dng lnh: Router(config-router)#neighbor ip-address remote-as AS-number Lnh ny cho router bit ID ca peer thit lp lng ging. 2.EBGP v IBGP Khi cu hnh BGP, Th BGP h tr hai loi phin thng tin gia cc peer -Phin thng tin gia cc EBGP: xy ra gia cc router khc AS. -Phin thng tin gia cc IBGP: xy ra gia cc rouer c cng AS

Nu ga tr ca AS trong cu hnh vi lnh router bgp ging vi ga tr ca AS trong lnh neighbor th quan h gia cc BGP l IBGP, cn nu khc th quan h l EBGP V d :

Trong v d ny th RTB thit lp phin thng tin EBGP vi RTA, v IBGP vi RTC. Trc ht ta s thit lp phin thng tin RTB vi RTC RTB(config)#router bgp 200 RTB(config-router)#neighbor 172.16.1.2 remote-as 200 RTB(config-router)#neighbor 172.16.1.2 updatesource loopback 0 i vi RTA th cng tng t nh RTC vi remote-as c gi tr l 100

Trong v d ny ta thy c lnh updatesource loopback 0 Nu c nhiu ng n router lng ging, router c th s dng bt k a ch IP ca cng giao tip no thit lp quan h lng ging. Trong trng hp ny th router s s dng cng loopback thit lp kt ni TCP vi router lng ging. RTB hc c cc route t IGB l OSPF, RTB c th qung b nhng mng ny bng cch redistribuate OSPF vo trong BGP hoc ta s dng lnh network RTB(config-router)#network 172.16.1.0 mask 255.255.255.252 RTB(config-router)#network 10.1.1.0 mask 255.255.255.252 RTB(config-router)#network 192.168.1.0

Cc thuc tnh ca BGP - Well-known mandatory l thuc tnh m phi tn ti trong cp nht ca BG v phi c nhn ra bi tt c cc nh cung cp, v cc khuyn ngh. - Well-known discretionary: L thuc tnh cng phi c nhn ra bi tt c cc khuyn ngh v BGP, nhng n c th khng c truyn i trong bng cp nht. - Optional Trasnitive : l mt thuc tnh m n khng yu cu phi c h tr bi tt c cc khuyn ngh v BGP. Tuy nhin nu n khng c nhn ra bi BGP th n s s dng c. Nu c c thit lp th BGP s chp nhn v chuyn tip n cc peer khc. - Optional nontranstivive : l mt thuc tnh cng khng yu cu phi c h tr bi cc khuyn ngh v BGP. Tuy nhin nu thuc tnh khng c nhn ra bi BGP, th n s s dng c, nu c khng c thit lp th thuc tnh s c loi b v khng c truyn vi cc peer khc.

1. Thuc tnh next hop: l mt thuc tnh well-known mandatory : n tng t nh trong IGP, n c network, th next hop l a ch IP ca router

qung b route. > i vi EBGP: th next hop l a ch ip ca lng ging qung b route. > i vi IBGP : Ni m route c qung t trong cng AS th next hop l a ch ip ca lng ging qung b route. Cn i vi route c qung b vo AS t EBGP, th next hop t EBGP khng c thay i vo trong IBGP, next hop l a ch ip ca EBGP lng ging m n hc c. > Khi mt route c qung b trong mt mi trng da truy nhp(multi-access) nh Ethernet, frame relay, th next hop l a ch IP ca cc cng giao tip ca router.

- Trong v d ny t RTC chy mt phin thng tin EBGP vi RTZ v IBGP vi RTA.

- RTC hc c route 128.213.1.0 t RTZ vi next hop l 1.1.1.1 do RTC nhn c route 128.213.1.0 n t lng ging RTZ bi next hop 1.1.1.1, khi n cp nht sang RTA th next hop ip address khng c thay i,

do d RTA c next hop l 1.1.1.1.Nh chng ta c th thy i vi RTA th next hop l 1.1.1.1 l khng th n c. 2. Thuc tnh Next Hop trong mi trng Multiaccess. Mt kt ni mng c xem l multiaccess nu c hn 2 host c th kt ni vo. Cc router trong kt ni mng multi-access th cng chia s chung mt a ch subnet v kt ni vt l trc tip vi nhau. Mt s mi trng l multi-access nh: Ethernet, Frame Relay, ATM. V d:

- Trong v d ny th ta thy RTC s qung co route hc c t RTB, v khi RTC qung co route th n ch ra RTB l source ca route, Nu khng th cc router khc s phi thc hin ng i theo s hop khng cn thit l qua RTC cc router trong cng mt mng(segment). - RTA,RTB,RTC : cng chia s mt mi trng truyn l multi-access. RTA v RTC chy EBGP, RTC v RTB chy OSPF. RTC hc mng 11.11.11.0/24 t RTB thng qua OSPF, v n qung co mng ny n RTA thng qua EBGP. V RTA v RTB chy khc giao thc nh tuyn, nn v logic th RTA xem RTC(10.10.10.2) l nt hop n c 11.11.11.0/24. Tuy nhin iu ny khng xy ra, trng thi ng cho RTA l xem RTB,10.10.10.3 l next hop v RTB cng cha s mt mi trng vi RTC.

3. Next Hop trong mng NBMA(Frame Relay) - Trong mng NBMA, Khng c cc kt ni trc tip gia cc router, m l ch nhng kt ni o c cu hnh t mi router n tt c cc router khc. Mt l do quan trng m hu ht cc t chc u th hin m hnh hup-and-spoke bi v gi c phi chng. Trong m hnh hub-and-spoke th nhiu site xa c cc kt ni o n mt hay nhiu router site trung tm. V d:

- y ta thy RTC l hub router v RTA, RTB l spoke router. ta thy cc kt ni o c t ra gia RTA v RTC, gia RTC v RTB, nhng khng c kt ni no gia RTA v RTB. RTA nhn c cp nht v mng 11.11.11.0/24 t RTC v n s c gng s dng RTB,10.10.10.3 lm next hop. iu ny tng t nh trong mi trng mng multi-access.Nhng trong trng hp ny th bng nh tuyn c vn v khng c kt ni o no gia RTA v RTB c. - gii quyt vn ny ta c gii php sau: s dng thuc tnh next-hop-self buc router, trong trng hp ny th, RTC s qung co mng 11.11.11.0/24 vi next hop l ca chnh n 10.10.10.2. RTA lc ny s gi trc tip cc gi n

mng 11.11.11.0/24 qua RTC. C php nh sau: Router(config-router)#neighbor ip-address next-hop-self

i vi RTC ta s dng lnh nh sau :

RTC(config-router)#neighbor 10.10.10.1 next-hop-self 4. Thuc tnh AS_path : l mt thuc tnh Wellknow mandatory. - N l tun t ca cc s AS m route truyn qua n ch. AS u tin truyn route s them s AS ca n v truyn di sang EBGP peer ca n. Sau th mi AS m nhn route ny s truyn route ny sang EBGP peer khc v gn them s AS ca n vo u danh sch cc s AS. Danh sch cui cng s l tt c cc s AS m route c truyn i qua, vi s AS ca AS m khi to route ban u nm cui danh sch. V danh sch ny c mang tun t cc s AS m route i qua. - BGP s dng thuc tnh AS_path ny trong cc cp nht ca n m bo mt m hnh khng b loop trn internet. Mi route c truyn i gia cc peer s mang theo mt danh sch ca cc s AS m route c truyn qua. Nu route c qung co n mt AS m khi to ra n, v AS s thy chnh n l mt phn trong danh sch cc s AS v n s khng chp nhn route ny. BGP router s chn them s AS ca n khi qung co bng nh tuyn cp nht ca n sang mt AS khc. Khi route c truyn qua mt BGP router c cng AS th danh sch AS_path s gi nguyn khng thay i. V d:

- Trong v d ny th ta thy route 172.16.10.0/24 c khi to t AS1 v c truyn i qua AS2, AS3, AS4 v truyn ngc tr li AS1. Nhn thy rng mi AS truyn route ny qua external peer th n thm s AS ca n vo u danh sch AS_path. Khi route truyn ngc tr li AS1, th BGB border router s nhn ra rng route ny tng qua n v khng chp nhn route ny. - Thng tin v AS_path l mt thuc tnh BGP xc inh ng i tt nht n ch. Khi so snh 2 hay nhiu route, gi s tt c cc thuc tnh khc u ging nhau, th route no c path ngn hn s c u tin chn hn. 5. AS_path v s private AS - Thng thng bo tn cc s AS, th cc khch hng m cc chnh sch nh tuyn ca h l s m rng ca cc chnh sch nh tuyn ca cc nh cung cp cho h c n nh cho cc AS khng hp l. V th nu khch hang l mt single-homed hay multihomed ca cng mt nh cung cp, th nh cung cp yu cu khch hang phi s dng s AS ly t private pool 64512 n 65535.. Nh vy th tt c cc cp nht m nh cung cp nhn c t khch hng ch gm cc s private AS. - Cc s private AS khng th qung co ra internet, v n l khng duy nht. V l do ny m cc s private AS s c ct b khi danh sch AS_path trc khi route c qung co ra ngoi internet.

V d:

- Trong v d ny th AS1 cung cp kt ni internet cho khch hng AS 65001. V khch hng ch kt ni n nh cung cp ny m khng c k hoach kt ni thm n mt nh cung cp khc trong tng lai gn , nn khc hng c n nh mt s private AS. Khch hng nn s dng mt s AS hp l khi cn c kt ni n mt nh cung cp khc na. - Prefix (172.16.220.0/24) c khi to t AS 65001 c AS_path 65001. Khi AS 1 qung b prefix ny ra internet, th n s c loi b s private AS. Khi prefix n internet th, n s c xem nh l c khi to t AS1 ca nh cung cp c AS_path l 1. BGP ch loi b s private AS ch khi n c quang b sang EBGP peer. iu ny ngha l vic loi b s private AS s c cu hnh trn RTB kt ni n RTC Cu hnh: RTB(config)#router bgp 1 RTB(config-router)#neighbor 172.16.20.2 remoteas 65001 RTB(config-router)#neighbor 192.168.6.3 remoteas 7 RTB(config-router)#neighbor 192.168.6.3 removeprivate-as Thuc tnh Atomic Aggregate : l mt thuc tnh wellknown discretionary. Thuc tnh Atomic Aggregate

c thit lp mt trong hai gi tr hoc l True hoc l False. Nu l True, th thuc tnh ny s cnh bo cho BGP router bit rng c nhiu ch c nhm li trong mt cp nht duy nht. Hay ni cch khc th, BGP router gi c nhiu route c th hn n ch nhng khng c gi i. Bi v iu ny cho nn gy ra mt vn , Atomic Aggregate cnh bo cho router nhn rng thng tin m chng nhn l khng cn thit cho tt c cc thng tin v route hin c. BGP c th c cu hnh tm tt route bng lnh aggregate-address. Lnh ny khng nht thit BGP phi to mt route aggregate trong bng nh tuyn ca n. M iu ny ch xy ra khi m router nhn bit c l c t nht mt route thuc v supernet ny. V th m nu router bit c ch mt route, n c th coi l bit c hng trm route khc. c im ny c s dng cnh bo . Aggregate route c qung co i khi n n t AS m thuc tnh Atomic aggregate c thit lp l True. iu ny cho bit c thng tin c th b mt. Mc nh th Atomic aggregate c thit lp l True, tr khi as-set c xc nh. Nu router ch qung b supernet, v khng qung b cc route c th hn th s dng summary-only. Khi cu hnh s dng key word ny th router s truyn supernet route v s loi b(suppress) cc route c th hn . V d: RTA(config)#router bgp 300 RTA(config-router)#neighbor 3.3.3.3 remote-as 200 RTA(config-router)#neighbor 2.2.2.2 remote-as 100 RTA(config-router)#network 160.10.0.0 RTA(config-router)#aggregate-address 160.0.0.0 255.0.0.0 Nu RTA loi b cc route c th hn supernet th ta cu hnh: RTA(config-router)#aggregate-address 160.0.0.0 255.0.0.0 summary-only Thuc tnh Aggregator: L mt thuc tnh Well-known discretionary. Khi cu hnh aggregation, th thuc tnh ny cung cp nhng thng tin v ID ca router v s AS ca ca router khi to aggregate route. Thuc tnh

ny cho php ISP admin xc nh router no thc hin aggregation. Thuc tnh Local Preference: L mt thuc tnh wellknown discretionary. Local Preference l mt yu t xc nh s so snh gia cc route n cng mt ch. Route c Local Preference cao hn s c chn lm ng i ti u. Cng nh tn ca thuc tnh ny, n ch chuyn i ni b gia cc IBGP peer . Local Preference khng qung co sang EBGP peer. Router trong mt multihomed AS c th hc rng, n c th n cng ch bng cc neighbor theo hai hay nhiu AS khc nhau. C th c hai hay nhiu im ri khi AS ni b n c mt ch no . S dng thuc tnh Local Preference p BGP router s dng route ti u hn cc route khc n cng mt ch. Bi v thuc tnh ny ch c thng tin gia cc BGP trong cng mt AS, tt c cc router c cng mt quyt nh chung n mt route bn ngoi. V d:

Theo v d ny th cng ty ANET mua kt ni n internet t hai nh cung cp, XNET v YNET. ANET c kt ni n YNET bng T3 v n XNET bng ng backup T1. Mt iu quan trong cho ANET l quyt nh ng n no cho ti ra ngoi internet. Tuy nhin admin ca ANET thch s dng kt ni T3 theo ng ca YNET. LA c th gn route n t YNET mt gi tr Local Prefernece 300, v San Jose gn cho route n t YNET mt gi tr thp hn l 200. Bi v c hai router LA v San Jose u chuyn i thng tin nh tuyn cp nht bng IBGP, chng u ng rng im ra khi AS bng ng qua YNET. V y c gi

tr Local Preference cao hn NET hc route n 128.213.0.0/16 bng ng qua XNET v YNET. Router LA v San Jose s ng s dng YNET l im n ch v ga tr Local Preference cao hn l 300. c. Vn dng Local Preference:

- Ta Thy AS 256 nhn cp nht mng 170.10.0.0 t AS 100 v t AS 300. C hai cch thit lp thuc tnh Local Preference trn cc router thuc AS 256. > S dng lnh bgp default local-

preference

preference

> S dng route map thit lp local

-S dng lnh bgp default local-preference, thit lp thuc tnh Local Preference trn RTC v RTD nh sau:

RTC(config)#router bgp 256 RTC(config-router)#neighbor 1.1.1.1 remote-as 100 RTC(config-router)#neighbor 128.213.11.2 remoteas 256 RTC(config-router)#bgp default local-preference

150 RTD(config)#router bgp 256 RTD(config-router)#neighbor 3.3.3.4 remote-as 300 RTD(config-router)#neighbor 128.213.11.1 remoteas 256 RTD(config-router)#bgp default local-preference 200 Cu hnh trn RTC lm cho n s thit lp tt c cc cp nht t AS100 mt gi tr Local Preference l 150. V t cu hnh trn RTD s lm cho n thit lp Local Preference cho ton b cp nht t AS 300 mt gi tr l 200. Bi v Local Prefernc ch trao i trong ni b AS, nn c hai RTC, v RTD u xc nh rng cp nht v mng 170.10.0.0 c gi tr Local Preference cao hn khi n n t AS300 so vi khi n n t AS100. Kt qu l ton b ti trong AS 256 n mng 170.10.0.0 u c truyn qua RTD. Ta c th cu hnh bng cch s dng route map. Route Map cung cp mt c ch uyn chuyn hn so vi vic s dng default nh trn. Khi ta s dng lnh bgp default local-preference cho RTD th tt c cc cp nht nhn c bi RTD u c thit lp gi tr l 200. iu ny gm c cp nht t AS34. By gi ta s cu hnh cho RTD s dng route map thit lp Local Preference trn RTD ch cho nhng cp nht t AS300. RTD(config)#ip as-path access-list 1 permit _300$ RTD(config)#route-map LP permit 10 RTD(config-route-map)#match as-path 1 RTD(config-route-map)#set local-preference 200 RTD(config)#route-map LP permit 20 RTD(config)#router bgp 256 RTD(config-router)#neighbor 3.3.3.4 remote- as 300 RTD(config-router)#neighbor 3.3.3.4 route-map LP in Thuc tnh Weight: Thuc tnh Weight tng t nh Local Preference, n s u tin s dng route c gi tr weight cao hn. Mt iu khc y l cc thng s weight ch c ngha ni b trong router thi m n s khng trao i vi cc router khc. Thuc tnh weight nh hng n cc route n t nhiu nh cung cp khc nhau ti mt router, mt router c nhiu kt ni ti hai hay nhiu nh cung cp. Thng s weight c tc ng cao hn

bt k thuc tnh no khc.N l thuc tnh quan trng nht xc nh route no u tin c chn hn. Weight c cu hnh trn cc router theo tng neighbor mt. thuc tnh ny s khng truyn sang cho bt k mt router BGP no khc c. Ta c minh ho sau :

Thuc tnh Multiple Exit Discriminator(MED) MED l mt thuc tnh optional nontransitive. MED ch cho lng ging external v ng i no ti u hn vo trong mt AS c nhiu im vo. MED c gi tr thp s tt hn. Khng ging Local Preference MED c trao i gia cc AS, nhng MED vo trong mt AS th s khng ri khi AS ny. Khi c mt cp nht vo trong mt AS vi mt gi tr MED c thit lp, th gi tr ny c s dng quyt nh ch trong ni b AS d thi. Khi BGP chuyn cp nht cho mt AS khc th gi tr ca MED c thit lp v 0. MED c th c s dng mt AS v nh hng n quyt inh ra khi AS ca mt AS khc. Khi mt route c khi to bi mt AS, th gi tr ca MED thng thng l tu theo metric IGP ca route. iu ny tr nn hu dng khi mt khch hng c nhiu kt ni n cng mt nh cung cp. IGP metric ch ra tiu tn n mt mng xc nh im truyn. Mt mng gn im xut A hn im xut B th s c gi tr IGP metric nh hn. Khi gi tr IGP metric c dch sang MED, ti n mt AS c th vo t mt kt ni gn ch hn. Chnh v iu ny m

MED c gi tr thp hn s c u tin hn n ch. iu ny c th c s dng cho c nh cung cp v c khch hng cn bng ti gia nhiu kt ni gia hai AS khc nhau. Ta s c mt v d minh ho nh sau

- T hnh v trn ta thy XNET nhn cp nht nh tuyn v mng 128.213.0.0/16 t 3 ngun khc nhau. l SJ c metric 120, LA c metric l 200, cn NY c metric l 50. SF s so snh hai gi tr metric t ANET v s u tin chon SJ hn v n qung co gi tr metric nh hn. Khi Lnh bgp always-compare-med c s dng trn router SF, n s tip tc so snh cc gi tr metric. N s so snh metric 120 vi 50 n t NY v s u tin chn NY hn n mng 128.213.0.0/16. - V d v cu hnh:

- Theo v d ny th ta thy : AS 100 s nhn cp nht v mng 180.10.0.0 t RTB, RTC, v RTD. RTC v RTD xut pht t AS 300, v RTB xut pht t AS 400. Ta s dng route map cu hnh MED cho router. RTB(config)#route-map med permit 10 RTB(config-route-map)#set metric 50 RTB(config)#router bgp 400 RTB(config-router)#neighbor 4.4.4.4 route-map med out Mc nh th BGP s so snh gi tr ca thuc tnh MED ca route n t cc lng ging c cng mt external AS. Nh AS 300 l mt v d. iu ny c ngha l RTA s so snh gi tr ca thuc tnh MED n t RTC c gi tr l 120 ch vi RTD vi gi tr l 200. Thm ch d cp nht n t RTB c gi tr MED thp hn th RTA cng s chn RTC l ng i tt nht n mng 180.10.0.0. p RTA s dng lun c cp nht v mng 180.10.0.0 n t RTB trong bng so snh ca n th ta s dng lnh bgp always-compare-med . Lc ny th RTA s chn RTB l next hop tt nht i n mng 180.10.0.0.0, trong trng hp gi d l tt c cc thuc tnh khc u nh nhau. . Thuc tnh Origin Origin l mt thuc tnh well-known mandatory. N ch ra ngun ca nh tuyn cp nht. BGP cho php 3 loi origin sau: IGP c khi to ni b trong AS EGP hc c t BGP Incomplete hc c t mt s cch khc nh redistribution - BGP xem xet cc thuc tnh Origin trong quyt nh route no ti u hn trong nhiu route. BGP chn loi origin thp nht. IGP thp hn EGP, EGP thp hn Incomplete

Xc inh tuyn trong BGP BGP da trn gi tr ca cc thuc tnh quyt nh chn tuyn. Khi gp nhiu route n cng mt ch, th BGP s chn route tt nht truyn ti n ch. Qu trnh chn route nh sau: Next Hop khng n c th route s b loi b. B v iu ny m ta bit ti sao phi c mt IGP route n next hop. BGP router s chn path no c weight ln nht. Nu cc route c weight u ging nhau th BGP router s chn route c Local Preference ln nht. Nu Local Preference c ga tr bng nhau cho tt c cc route th BGP s chn route m c khi to bi ni b router Nu Local Preference c gi tr nh nhau th BGP router s chn route c AS_path ngn nht. Nu AS_path c chiu di bng nhau, th router BGP s chn route c loi origin thp nht. Tc l IGP thp hn EGP, v EGP thp hn Incomplete. Nu loi origin ging nhau, BGP router s chn route c MED nh nht. Nu MED c gi tr gng nhau th BGP s chn route theo cch sau. External(EBGP) s c u tin hn confederation external, n li c u tin hn so vi IBGP. Nu tt c nhng thuc tnh xt n u ging nhau, th BGP s chn route m c th n c theo ng ca IGP lng ging gn nht. Tc by gi s xt n path n ch theo path ngn nht n next hop. Nu tt c cng u ging nhau th BGP s chn route n t router c ID nh nht. Router ID thng l a ch IP cao nht ca router hay l a ch ca cng

loopback

Lc tuyn v chnh sch nh tuyn 1. Lc tuyn

Lc tuyn cho php router chn route no s c trao i vi BGP peer no. Lc tuyn l mt phn ca chnh sch nh tuyn. Mt AS c th kim sot route no s c chp nhn t lng ging EBGP Cc chnh sch c th c nh ngha bng vic lc cc route. BGP route truyn qua cc b phn lc c th gm c cc thuc tnh ca n v c vn dng vo trong vic quyt nh chn route. C hai vic lc ti inbound v outbound u c chp nhn gia cc peer v c giao thc nh tuyn chy trn cng mt router. Lc inbound ch ra rng BGP lc cp nht nh tuyn n t mt peer khc. Cn Lc outbound th hn ch vic cp nht nh tuyn t router ny n cc Peer khc. cp giao thc th : lc inbound c tc dng hn ch cp nht nh tuyn c redistribution vo trong mt giao thc. Cn lc utbound hn ch vic cp nht nh tuyn chn vo t giao thc ny.Vi BGP th ta c mt v d sau : lc inbound ngha l hn ch cp nht nh tuyn c redistribution t mt giao thc nh tuyn khc vo trong BGP, cn lc outbound th hn ch cp nht c redistribution t BGP vo mt giao thc khc (IGP) 2. S dng distribute-list lc route hn ch thng tin nh tuyn m router hoc hay qung co. p dng lc tuyn t hay n mt lng ging no s dng lnh distribute-list. Nh minh ho di y:

Ta thy RTD trong AS2 khi to mng 192.68.10.0 v truyn n RTF. RTF s truyn cp nht n RTA bi IBGP, v t n s truyn cp nht n AS1. Nh vy AS3 s tr thnh transit AS qung co rng n c th n c mng 192.68.10.0/24 ngn tnh trng hp ny xy ra th ta cu hnh trn RTA: RTA(config)#router bgp 3 RTA(config-router)#neighbor 172.16.1.1 remote-as 3 RTA(config-router)#neighbor 172.16.20.1 remoteas 1 RTA(config-router)#neighbor 172.16.20.1 distribute-list 1 out RTA(config)#access-list 1 permit ip 172.16.0.0 0.0.255.255 Ta thy distribute-list, c s dng l mt phn ca lnh neighbor, n ngn RTA khng qung co mng 192.68.10.0/24 n RTC. Access list c s dng nhn ra prefix thc hin lc v distribute-list out p dng lc cp nht ra bn ngoi. Nhn thy rng khi cu hnh distribute lt da trn mt access list . Nu s dng standard access list th s c mt s chc nng b hn ch. RTA kt ni n nhiu subnet trong mng 172.16.0.0/16. Mc ch ca vic qung co mt a ch mng tm tt 172.16.0.0/16, nhng khnng qung co bt k subnet ring no ca n c. Mt standard access list s khng lm c iu

ny bi v n s cho php (permit) nhiu hn mong i. N s lc d trn a ch mng. y l mt v d v mt access list m n s permit khng ch mng 172.16.0.0/16 m l tt c cc thnh phn khc thuc tm tt route ny. access-list 1 permit 172.16.0.0 0.0.255.255 hn ch cp nht ch 172.16.0.0/16 ta s dng extended access list. Thng thng th mt extended access list gm c source v destination. Trong trng hp lc route BGP , th mt extended access list ch gm c network, tip theo l subnet mask. C network v mask u cha wildcard bitmask ca n, c c php nh sau: router(config)#access-list number permit|deny network network-wildcard mask mask-wildcard cho php route tm tt nh trong v d trn th ta cu hnh mt extended access list filter network v 16 bit mask ca pref. Vi cu hnh ny th RTA s khng truyn subnet route nh 172.16.0.0/17 hay 172.16.10/24 trong cp nht ca n n AS1. RTA(config)#access-list 101 permit ip 172.16.0.0 0.0.255.255 255.255.0.0 0.0.0.0 - Ta c th s dng ip prefix-list thay cho extended access list. 3. Lnh ip prefix-list: s dng lnh ip prefix-list c mt s thun li hn so vi vic s dng access-list l Hiu sut c ci thin khi loading v tm route trong mt danh sch ln. H tr cp nht tng phn increment update. Lc route vi extended access list khng h tr cho vic cp nht tng phn. Dng lnh than thin hn Tnh uyn chuyn cao - C php ca lnh nh sau : router(config)#ip prefix-list list-name [seq seqvalue] deny/permit network/len [ge ge-value] [le

le-value] . V d v cu hnh bng lnh ip prefix-list RTA(config)#ip prefix-list GROVER permit 192.0.0.0/8 le 24 RTA(config)#ip prefix-list GROVER deny 192.0.0.0/8 ge 25 Theo v d ny th cu lnh u tin chp nhn tt c cc route c cc chiu di mask ln n 24 bit vi prefix 192.0.0.0/8, v t chi (deny) t c cc route c th hn. cu lnh th hai th n s kim tra prefix bt u vi 192 octet u tin. Sau quan tm n ch cc route c th hn bng cch kim tra chiu di ca mask. V th c 192.168.32.0/19 v 192.168.1.0/24 u c trng thi cho php(permit), nhng mng prefix 192.168.1.32/27 th khng bi v chiu di mask ca n ln hn 25. c ge v le c th c s dng chung theo lnh sau: RTA(config)#ip prefix-list OSCAR permit 10.0.0.0/8 ge 16 le 24 Lnh ny permit tt c prefix trong mng 10.0.0.0/8 vi chiu di mask t 16 cho n 24 bits. Mi prefix list c gn cho mt s th t, s ny c gn mc nh hoc c gn bng tay. Bng cch nh s, mt entry c th c chn vo ti bt k im no ca list. iu ny quan trng v router kim tra prefix list t tun t t nh n ln. Khi c mt match xy ra th router s khng tip tc tt n cc entry ca cc tun t sau na. Ta c th s dng lnh show ip prefix-list kim tra. S tun t ny s t ng c to ra v tng dn tng bc +5. gi tr u tin c to ra trong prefix list l 5 tip theo l 10, 15.. Nu cu hnh bng tay mt gi tr v tip theo khng xc nh cc gi tr th s th t cho entry s t ng tng ln theo bc +5. V d gi tr u tin c xc nh l 3. v sau th khng c tun t c ch nh cho cc entry khc th s tun t s c tao ra l 8, 13, 18.v du:

RTA(config)#ip prefix-list ELMO seq 12 deny 192.168.1.0/24 Cui cng khi s dng prefix list th ta phi theo mt s lut sau Mt prefix list trng s mc inh l permit tt c prefix C mt ngm nh deny c a ra nu prefix khng match bt k entry no ca prefix. Khi c nhiu entry ca prefix list match, th tun t ca entry no nh nht s c match tht s

Redistribute trong BGP 1. Tng quan v redistribute - Khi s dng giao thc BGP, vn m bo route chnh xc l rt quan trng. C mt mi quan h gn gia cc route ng trn internet v cch thc chn route vo BGP. Thng tin c th chn v BGP theo cch ng hoc tnh. Bng cch chn route bng cch ng th route n hay truyn i t bng nh tuyn BGP, ph thuc vo trng thi ca tng mng mt. Bng cch chn route theo cch tnh th n c bo ton trong bng nh tuyn ca BGP, v n khng quan tm n trng thi ca cc mng m n nhn ra trong cu hnh. V th trong khi qung co ng s kt thc nu mng c qung co khng cn tn ti na. Cn i vi qung tnh th s khng b nh vy m n s lun khng thay i. - Bng cch chn tuyn ng th tt c cc tuyn trong IGP c phn phi li vo trong BGP s dng lnh redistribution. Ta c th s dng lnh network phn phi na ng(semi-dynamic) - Thng tin c chn ng v BGP bng cch cho php IGP route nh RIP, OSPF, EIGRP c th phn phi li vo trong BGP. bng cch phn phi li ng th d cu hnh. Ton b IGP route u c chn vo BGP, m khng quan tm n giao thc ng c s dng. - i vi semi-dynamic th thng tin c s dng

chn vo BGP c xc nh l tp con ca IGP route thi. Bng cch ny qung co tng route ring vo trong BGP vi lnh network. Tuy nhin khi s dng lnh network th phi cn thit cho mi prefix. Do khi s lng mng qu ln th vic s dng semidynamic s khng thc t. - Bng cch s dng lnh network qung co mng trong IGP domain. Vi cch ny th nu IGP khng hc c route ni b th BGP s khng qung co mng ny cho cc BGP router khc. Tuy nhin ta c th s dng lnh no synchronization disable s kim tra ny. Lc ny th BGP c th qung co network m n khng th n c.

2. Vic chn nhng thng tin li hay khng mong mun. - Vic chn route vo BGP bng lnh network khng phi lun lun thc t, hoc kh thi. Cn i vi vic chn route bng cch phn phi li th c th mang li kt qu l gy ra bt li cho AS khc nh nhng thng tin khng c chp nhn, sai, hay khng mng i. Phn phi li ton b IGP c th dn n l ton b a ch private, hay a ch khng hp le (illegal ) c qung co ra bn ngoi AS. - Vic phn phi li thng tin qua li gia IGP v BGP c th gy nn kt qua l qung co nhng thng tin nh tuyn b tn hi. Trong trng hp ny th cc route m BGP c chn vo t bn ngoi c th truyn ngc tr li vo BGP bng IGP. iu ny xy ra lm cho route ny c khi to chnh ti trong AS ch khng cn t AS khc a ti na. v d :

- Trong trng hp ny th ta thy AS100 qung co mng NetA sang AS200 theo BGP v RTC chn thng tin ny vo IGP, v n hc c thng tin ny. RTC c cu hnh redistribute thng tin IGP vo trong BGP. Lc ny th NetA s kt thc qung co bi AS100 v n c xem nh c khi to v c qung co i ti AS200. Lc ny th NetA c hai ngun mt t AS100, v mt t AS200. - gii quyt vn ny th ta c th s dng lc cc route, xc nh c l ch nhng route no mi c chn vo BGP t IGP thi.

3.v d v cu hinh phn phi li(redistribution)

Ta s cu hnh trn RTB redistribute t OSPF vo BGP bng cch ng RTB(config)#router bgp 200 RTB(config-router)#neighbor 10.1.1.2 remote-as 100 RTB(config-router)#neighbor 10.1.1.2 route-map BLOCK-BAD-ADDRESSES out RTB(config-router)#redistribute ospf 1 match internal metric 50 RTB(config-router)#redistribute static Ta c th cu hnh cho RTB ch chn mt s mng vo BGP thi. Cn tt c cc route khc s khng c chn vo BGP nn khng oc qung co ra ben ngoi khi AS.

RTB(config)#router bgp 200 RTB(config-router)#neighbor 10.1.1.2 remote-as 100 RTB(config-router)#network 192.168.1.0 RTB(config-router)#network 192.168.2.0 - Trong trng hp ny ch c mng 192.168.1.0 v 192.168.2.0 l c chn vo BGP thi.

Cu hnh Thc t

1. Cu hnh cho s 1

Theo s ny th ta thy R2, R3, R4 quan h IBGP vi nhau thuc AS100, cn R1 thuc AS300, R6 thuc AS400, R5 thuc AS200 cu hnh cho tng router mt:

R1#show run Building configuration...

Current configuration: ! version 12.0 service timestamps debug uptime

service timestamps log uptime no service password-encryption ! hostname R1 ! ! memory-size iomem 10 ip subnet-zero no ip domain-lookup ! ! ! ! ! interface Loopback0 ip address 192.168.250.1 255.255.255.0 no ip directed-broadcast ! interface Loopback1 ip address 192.168.1.213 255.255.255.252 no ip directed-broadcast ! interface Loopback12 no ip address

no ip directed-broadcast ! interface Ethernet0/0 no ip address no ip directed-broadcast shutdown ! interface Serial0/0 ip address 192.168.1.210 255.255.255.252 no ip directed-broadcast no ip mroute-cache no fair-queue clockrate 64000 ! router bgp 300 network 192.168.1.212 network 192.168.250.0 neighbor 192.168.1.209 remote-as 100 no auto-summary ! ip classless ! ! !

line con 0 logging synchronous transport input none line aux 0 line vty 0 4 ! no scheduler allocate end

R2#show runn Building configuration...

Current configuration: ! version 12.1 service timestamps debug uptime service timestamps log uptime no service password-encryption ! hostname R2 ! ! ! !

! ! ip subnet-zero no ip domain-lookup ! ! ! ! interface Ethernet0 ip address 192.168.1.226 255.255.255.252 interface Serial0 ip address 192.168.1.221 255.255.255.252 no fair-queue clockrate 64000 ! interface Serial1 ip address 192.168.1.209 255.255.255.252 ! router bgp 100 no synchronization network 192.168.1.224 mask 255.255.255.252 neighbor 192.168.1.197 remote-as 100 neighbor 192.168.1.210 remote-as 300 neighbor 192.168.1.222 remote-as 100

neighbor 192.168.1.225 remote-as 200 ! ip classless no ip http server ! ! line con 0 logging synchronous transport input none line aux 0 line vty 0 4 ! no scheduler allocate end


Current configuration : 891 bytes ! version 12.2 no parser cache no service single-slot-reload-enable service timestamps debug uptime

service timestamps log uptime no service password-encryption ! hostname R3 ! logging rate-limit console 10 except errors ! ! ! memory-size iomem 10 ip subnet-zero ! ! no ip domain-lookup ! no ip dhcp-client network-discovery call rsvp-sync ! ! ! ! ! ! !

! interface Ethernet0/0 no ip address shutdown half-duplex ! interface Serial0/0 ip address 192.168.1.222 255.255.255.252 no fair-queue ! interface Serial0/1 ip address 192.168.1.198 255.255.255.252 ! router bgp 100 no synchronization bgp log-neighbor-changes network 192.168.1.196 mask 255.255.255.252 network 192.168.1.220 mask 255.255.255.252 neighbor 192.168.1.197 remote-as 100 neighbor 192.168.1.221 remote-as 100 ! ip classless ip http server !

! ! ! voice-port 1/1/0 ! voice-port 1/1/1 ! dial-peer cor custom ! ! ! ! line con 0 logging synchronous line aux 0 line vty 5 15 ! end

R4#show runn Current configuration : 904 bytes ! version 12.2

service timestamps debug datetime msec service timestamps log datetime msec no service password-encryption ! hostname R4 ! logging queue-limit 100 ! ip subnet-zero ! ! no ip domain lookup ! mpls ldp logging neighbor-changes ! ! ! ! ! ! ! no voice hpi capture buffer no voice hpi capture destination !

! mta receive maximum-recipients 0 ! ! ! ! interface Ethernet0/0 ip address 192.168.1.106 255.255.255.252 half-duplex ! interface Serial0/0 ip address 192.168.1.197 255.255.255.252 clockrate 64000 ! interface Serial0/1 no ip address ! router bgp 100 no synchronization bgp log-neighbor-changes network 192.168.1.204 mask 255.255.255.252 neighbor 192.168.1.198 remote-as 100 neighbor 192.168.1.205 remote-as 400 no auto-summary

! no ip http server ip classless ! ! ! ! ! call rsvp-sync ! ! mgcp profile default ! dial-peer cor custom ! ! line con 0 logging synchronous line aux 0 line vty 0 4 ! ! end R5#show runn

Building configuration...

Current configuration : 1080 bytes ! version 12.2 service timestamps debug datetime msec service timestamps log datetime msec no service password-encryption ! hostname R5 ! logging queue-limit 100 ! memory-size iomem 10 ip subnet-zero ! ! no ip domain lookup ! mpls ldp logging neighbor-changes ! ! ! !

! ! ! no voice hpi capture buffer no voice hpi capture destination ! ! mta receive maximum-recipients 0 ! ! ! ! interface Loopback0 ip address 192.168.100.1 255.255.255.0 ! interface Loopback1 ip address 192.168.200.1 255.255.255.0 ! interface Loopback2 ip address 192.168.1.217 255.255.255.252 ! interface Ethernet0/0 ip address 192.168.1.225 255.255.255.252 half-duplex

! interface Serial0/0 no ip address shutdown clockrate 64000 ! router bgp 200 no synchronization bgp log-neighbor-changes network 192.168.1.216 network 192.168.100.0 network 192.168.200.0 neighbor 192.168.1.226 remote-as 100 no auto-summary ! no ip http server ip classless ! ! ! line con 0 logging synchronous transport input none line aux 0

line vty 0 4 ! no scheduler allocate end R6#show runn Building configuration...

Current configuration : 1056 bytes ! version 12.2 service timestamps debug datetime msec service timestamps log datetime msec no service password-encryption ! hostname R6 ! logging queue-limit 100 ! memory-size iomem 10 ip subnet-zero ! ! no ip domain lookup !

mpls ldp logging neighbor-changes ! ! ! ! ! ! ! ! no voice hpi capture buffer no voice hpi capture destination ! ! mta receive maximum-recipients 0 ! ! ! ! interface Loopback0 ip address 192.168.50.1 255.255.255.0 ! interface Loopback1 ip address 192.168.75.1 255.255.255.0 !

interface Loopback2 ip address 192.168.1.201 255.255.255.252 ! interface Ethernet0/0 ip address 192.168.1.205 255.255.255.252 half-duplex ! interface Serial0/0 no ip address shutdown ! router bgp 400 no synchronization bgp log-neighbor-changes network 192.168.1.200 network 192.168.50.0 network 192.168.75.0 neighbor 192.168.1.206 remote-as 100 no auto-summary ! ip http server ip classless ! !

! ! call rsvp-sync ! ! mgcp profile default ! dial-peer cor custom ! ! ! ! line con 0 logging synchronous line aux 0 line vty 0 4 ! ! end

By gi ta show ip bgp ca R4 : R4#show ip bgp

BGP table version is 1, local router ID is 192.168.1.206 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal, r RIB-failure, S Stale Origin codes: i - IGP, e - EGP, ? - incomplete

Network Weight Path

Next Hop

Metric LocPrf

* i192.168.1.196/30 192.168.1.198 100 0i * 192.168.1.204/30 0.0.0.0 i * i192.168.1.220/30 192.168.1.198 100 0i * 192.168.50.0 400 i * 192.168.75.0 400 i 192.168.1.205 0 0

0

32768

0

0

192.168.1.205

0

0

Ta thy ch c mng 50.0 v 75.0 ch khng c cc mng khc t cc AS300,200 Tng t ta s xem trn R2 ta R2#show ip bgp BGP table version is 23, local router ID is 192.168.1.226 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal Origin codes: i - IGP, e - EGP, ? - incomplete

Network Weight Path

Next Hop

Metric LocPrf

*>i192.168.1.196/30 192.168.1.222 100 0i *> 192.168.1.208/30 0.0.0.0 32768 i *> 192.168.1.220/30 0.0.0.0 32768 i *i 192.168.1.222 0 0

0

0

100 0

0i

*> 192.168.1.224/30 0.0.0.0 32768 i *> 192.168.100.0 0 200 i *> 192.168.200.0 0 200 i *> 192.168.250.0 0 300 i 192.168.1.225

0

192.168.1.225

0

192.168.1.210

0

Ta thy trn bng nh tuyn BGP ca R2 cng ch c cc mng ca AS300,200 thi ch khng c cc mng ca AS400 qung co qua AS100 Do R3 kh ng c p nh t b ng nh tuy n c a n cho c c IBGP kh c Ta s xem b ng nh tuy n BGP c a R3 R3#show ip bgp BGP table version is 4, local router ID is 192.168.1.222 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal Origin codes: i - IGP, e - EGP, ? - incomplete

Network Weight Path

Next Hop

Metric LocPrf

*> 192.168.1.196/30 0.0.0.0 32768 i *>i192.168.1.204/30 192.168.1.197 100 0i *> 192.168.1.220/30 0.0.0.0 32768 i * i192.168.50.0 0 400 i * i192.168.75.0 0 400 i * i192.168.100.0 0 200 i * i192.168.200.0 0 200 i * i192.168.250.0 0 300 i 192.168.1.205

0

0

0

0

100

192.168.1.205

0

100

192.168.1.225

0

100

192.168.1.225

0

100

192.168.1.210

0

100

R3 cha tt c cc mng vy By gi ta xem th bng thit lp lng ging ca R4 v R2 th xem

R4#show ip bgp summ BGP router identifier 192.168.1.206, local AS number 100 BGP table version is 12, main routing table version 12 5 network entries using 505 bytes of memory

5 path entries using 240 bytes of memory 3 BGP path attribute entries using 180 bytes of memory 1 BGP AS-PATH entries using 24 bytes of memory 0 BGP route-map cache entries using 0 bytes of memory 0 BGP filter-list cache entries using 0 bytes of memory BGP using 949 total bytes of memory BGP activity 15/10 prefixes, 19/14 paths, scan interval 60 secs

Neighbor V AS MsgRcvd MsgSent InQ OutQ Up/Down State/PfxRcd 192.168.1.198 12 0 192.168.1.205 12 0 192.168.1.221 0 0 4 100 48 00:14:58 4 400 50 00:09:35 100 0 never 57

TblVer

0

2

0

2

58

4 0

active

0

Ta s s dng IGP d gp R2 v R4 thit lp neighbor vi nhau

R2(config)#router ospf 1 R2(config-router)#net 192.168.1.220 0.0.0.3 area 0 R2(config-router)#net 192.168.1.196 0.0.0.3 area 0

R3(config)#router ospf 1

R3(config-router)#net 192.168.1.196 0.0.0.3 area 0 R3(config-router)#net 192.168.1.220 0.0.0.3 area 0

R4(config)#router ospf 1 R4(config-router)#net 192.168.1.196 0.0.0.3 area 0

R4#show ip bgp summ BGP router identifier 192.168.1.206, local AS number 100 BGP table version is 15, main routing table version 15 10 network entries using 1010 bytes of memory 10 path entries using 480 bytes of memory 5 BGP path attribute entries using 300 bytes of memory 3 BGP AS-PATH entries using 72 bytes of memory 0 BGP route-map cache entries using 0 bytes of memory 0 BGP filter-list cache entries using 0 bytes of memory BGP using 1862 total bytes of memory BGP activity 20/10 prefixes, 29/19 paths, scan interval 60 secs

Neighbor V AS MsgRcvd MsgSent OutQ Up/Down State/PfxRcd 192.168.1.198 4 100 0 0 00:08:59 2 74

TblVer InQ

87

15

192.168.1.205 4 400 0 0 00:27:36 2 192.168.1.221 4 100 0 0 00:00:33 5

68

78

15

6

6

15

By gi th R4 v R2 thit lp c quan h lng ging ri R4#show ip bgp BGP table version is 17, local router ID is 192.168.1.206 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal, r RIB-failure, S Stale Origin codes: i - IGP, e - EGP, ? - incomplete

Network Weight Path

Next Hop

Metric LocPrf

r>i192.168.1.196/30 192.168.1.198 100 0i *> 192.168.1.204/30 0.0.0.0 32768 i * i192.168.1.208/30 192.168.1.221 100 0i >i192.168.1.220/30 192.168.1.198 100 0i * i192.168.1.224/30 192.168.1.221 100 0i *> 192.168.50.0 400 i *> 192.168.75.0 400 i 192.168.1.205 0

0

0

0

0

0

0

192.168.1.205

0

0

* i192.168.100.0 0 200 i * i192.168.200.0 0 200 i * i192.168.250.0 0 300 i

192.168.1.225

0

100

192.168.1.225

0

100

192.168.1.210

0

100

Bt g ta xt ti ng b gia BGP v IGP Trc ht ta xem bng nh tuyn ca R3 trc khi ng b

R3#show ip route Codes: C - connected, S - static, I - IGRP, R - RIP, M mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA OSPF inter area N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area * - candidate default, U - per-user static route, o - ODR P - periodic downloaded static route

Gateway of last resort is not set

B

192.168.75.0/24 [200/0] via 192.168.1.205,

00:01:27 B 192.168.200.0/24 [200/0] via 192.168.1.225, 00:03:03 B 192.168.250.0/24 [200/0] via 192.168.1.210, 00:14:01 B 192.168.50.0/24 [200/0] via 192.168.1.205, 00:01:27 192.168.1.0/30 is subnetted, 5 subnets B 192.168.1.224 [200/0] via 192.168.1.221, 00:03:22 B 192.168.1.204 [200/0] via 192.168.1.197, 00:01:59 C C 192.168.1.196 is directly connected, Serial0/1 192.168.1.220 is directly connected, Serial0/0

B 192.168.1.208 [200/0] via 192.168.1.221, 00:14:03 B 192.168.100.0/24 [200/0] via 192.168.1.225, 00:03:04

Tip theo ta s cu hnh trn R3 v R4 nh sau R3(config)#routrer bgp 100 R3(config-router)#synchronization

R4(config)#routrer bgp 100 R4(config-router)#redistribute bgp 100 subnets



O E2 192.168.75.0/24 [110/1] via 192.168.1.197, 00:02:25, Serial0/1 O E2 192.168.50.0/24 [110/1] via 192.168.1.197, 00:02:25, Serial0/1 192.168.1.0/30 is subnetted, 3 subnets O E2 192.168.1.204 [110/1] via 192.168.1.197, 00:02:25, Serial0/1 C C 192.168.1.196 is directly connected, Serial0/1 192.168.1.220 is directly connected, Serial0/0

R2(config)#routrer bgp 100 R2(config-router)#redistribute bgp 100 subnets



O E2 192.168.75.0/24 [110/1] via 192.168.1.197, 00:00:07, Serial0/1 O E2 192.168.200.0/24 [110/1] via 192.168.1.221, 00:00:07, Serial0/0 O E2 192.168.250.0/24 [110/1] via 192.168.1.221,

00:00:07, Serial0/0 O E2 192.168.50.0/24 [110/1] via 192.168.1.197, 00:00:07, Serial0/1 192.168.1.0/30 is subnetted, 5 subnets O E2 192.168.1.224 [110/1] via 192.168.1.221, 00:00:07, Serial0/0 O E2 192.168.1.204 [110/1] via 192.168.1.197, 00:00:07, Serial0/1 C C 192.168.1.196 is directly connected, Serial0/1 192.168.1.220 is directly connected, Serial0/0

O E2 192.168.1.208 [110/1] via 192.168.1.221, 00:00:08, Serial0/0 O E2 192.168.100.0/24 [110/1] via 192.168.1.221, 00:00:08, Serial0/0

Tng t th i vi R4 th bng nh tuyn ca n trc v sau khi s dng lnh synchronization nh sau R4#show ip route Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA OSPF inter area N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2 i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area * - candidate default, U - per-user static route, o - ODR

P - periodic downloaded static route


B 192.168.75.0/24 [20/0] via 192.168.1.205, 00:34:47 B 192.168.50.0/24 [20/0] via 192.168.1.205, 00:34:47 192.168.1.0/30 is subnetted, 3 subnets C 192.168.1.204 is directly connected, Ethernet0/0 C 192.168.1.196 is directly connected, Serial0/1

O 192.168.1.220 [110/128] via 192.168.1.198, 00:04:31, Serial0/1

R4# show ip route Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA OSPF inter area N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2 i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area * - candidate default, U - per-user static route, o - ODR

P - periodic downloaded static route


B 192.168.75.0/24 [20/0] via 192.168.1.205, 00:10:40 O E2 192.168.10.0/24 [110/1] via 192.168.1.198, 00:01:47, Serial0/1 O E2 192.168.11.0/24 [110/1] via 192.168.1.198, 00:01:47, Serial0/1 O E2 192.168.200.0/24 [110/1] via 192.168.1.198, 00:06:10, Serial0/1 O E2 192.168.250.0/24 [110/1] via 192.168.1.198, 00:06:10, Serial0/1 B 192.168.50.0/24 [20/0] via 192.168.1.205, 00:10:40 192.168.1.0/30 is subnetted, 5 subnets O E2 192.168.1.224 [110/1] via 192.168.1.198, 00:06:10, Serial0/1 C 192.168.1.204 is directly connected, Ethernet0/0 C 192.168.1.196 is directly connected, Serial0/1

O 192.168.1.220 [110/128] via 192.168.1.198, 00:06:11, Serial0/1 O E2 192.168.1.208 [110/1] via 192.168.1.198, 00:06:11, Serial0/1 O E2 192.168.100.0/24 [110/1] via 192.168.1.198, 00:06:11, Serial0/1

Tip theo ta s b OSPF v s dng static route d BGP thit lp quan h lng ging gia R2, v R4,

nhng trc ht ta phi cu hnh R3 no syn gia BGP v IGP

R3(config)#routrer bgp 100 R3(config-router)#no synchronization

Sau ta cu hnh nh tuyn tnh th cng cho kt qu tng t nh trn

R2(config)#ip route 192.168.1.197 255.255.255.252 192.168.1.222 R4(config)#ip route 192.168.1.220 255.255.255.252 192.168.1.198

R4#show ip route Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA OSPF inter area N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2 i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area * - candidate default, U - per-user static route, o - ODR P - periodic downloaded static route


B 192.168.75.0/24 [20/0] via 192.168.1.205, 00:00:07 B 192.168.10.0/24 [200/0] via 192.168.1.221, 00:00:07 B 192.168.11.0/24 [200/0] via 192.168.1.221, 00:00:07 B 192.168.200.0/24 [200/0] via 192.168.1.221, 00:00:07 B 192.168.250.0/24 [200/0] via 192.168.1.221, 00:00:07 B 192.168.50.0/24 [20/0] via 192.168.1.205, 00:00:07 192.168.1.0/30 is subnetted, 3 subnets C 192.168.1.204 is directly connected, Ethernet0/0 C S 192.168.1.196 is directly connected, Serial0/1 192.168.1.220 [1/0] via 192.168.1.198

B 192.168.100.0/24 [200/0] via 192.168.1.221, 00:00:08

R2#show ip route Codes: C - connected, S - static, I - IGRP, R - RIP, M mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA OSPF inter area N1 - OSPF NSSA external type 1, N2 - OSPF NSSA

external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area * - candidate default, U - per-user static route, o - ODR P - periodic downloaded static route


B 192.168.75.0/24 [200/0] via 192.168.1.197, 00:00:42 B 192.168.10.0/24 [20/0] via 192.168.1.225, 00:03:52 B 192.168.11.0/24 [20/0] via 192.168.1.225, 00:03:52 B 192.168.200.0/24 [20/0] via 192.168.1.225, 00:03:52 B 192.168.250.0/24 [20/0] via 192.168.1.210, 00:03:55 B 192.168.50.0/24 [200/0] via 192.168.1.197, 00:00:42 192.168.1.0/30 is subnetted, 4 subnets C S C C 192.168.1.224 is directly connected, Ethernet0 192.168.1.196 [1/0] via 192.168.1.222 192.168.1.220 is directly connected, Serial0 192.168.1.208 is directly connected, Serial1

B 192.168.100.0/24 [20/0] via 192.168.1.225, 00:03:54

Cu hnh cho s 2(cu hnh v aggregation)

u tin ta s cu hnh cho R1 v R2 u qung b mng tm tt 192.168.192.0/21 qua AS 200 R1#show runn Building configuration...

Current configuration : 1432 bytes !

version 12.2 service timestamps debug datetime msec service timestamps log datetime msec no service password-encryption ! hostname R1 ! logging queue-limit 100 ! memory-size iomem 10 ip subnet-zero ! ! no ip domain lookup ! mpls ldp logging neighbor-changes ! ! ! ! ! ! ! no voice hpi capture buffer

no voice hpi capture destination ! ! mta receive maximum-recipients 0 ! ! ! ! interface Loopback0 ip address 192.168.192.1 255.255.255.0 ! interface Loopback1 ip address 192.168.193.1 255.255.255.0 ! interface Loopback2 ip address 192.168.194.1 255.255.255.0 ! interface Loopback3 ip address 192.168.195.1 255.255.255.0 ! interface Ethernet0/0 ip address 192.168.1.201 255.255.255.252 half-duplex !

interface Serial0/0 ip address 192.168.1.254 255.255.255.252 clockrate 64000 ! router eigrp 1 passive-interface Serial0/0 network 192.168.1.0 network 192.168.192.0 network 192.168.193.0 network 192.168.194.0 network 192.168.195.0 no auto-summary ! router bgp 100 no synchronization bgp log-neighbor-changes aggregate-address 192.168.192.0 255.255.248.0 redistribute eigrp 1 neighbor 192.168.1.202 remote-as 100 neighbor 192.168.1.202 next-hop-self neighbor 192.168.1.253 remote-as 200 no auto-summary ! no ip http server

ip classless ! ! ! ! ! call rsvp-sync ! ! mgcp profile default ! dial-peer cor custom ! ! ! line con 0 logging synchronous line aux 0 line vty 0 4 password cisco login ! ! end


Current configuration: ! version 12.0 service timestamps debug uptime service timestamps log uptime no service password-encryption ! hostname R2 ! ! ! ! ! ! ip subnet-zero no ip domain-lookup ! ! ! process-max-time 200

! interface Ethernet0 ip address 192.168.1.238 255.255.255.252 no ip directed-broadcast ! interface Serial0 ip address 192.168.1.249 255.255.255.252 no ip directed-broadcast no ip mroute-cache no fair-queue ! interface Serial1 ip address 192.168.1.253 255.255.255.252 no ip directed-broadcast ! router bgp 200 neighbor 192.168.1.237 remote-as 200 neighbor 192.168.1.237 next-hop-self neighbor 192.168.1.250 remote-as 300 neighbor 192.168.1.254 remote-as 100 ! ip classless no ip http server !

! line con 0 logging synchronous transport input none line aux 0 line vty 0 4 login ! end R3#show runn Building configuration...

Current configuration: ! version 11.3 service timestamps debug uptime service timestamps log uptime no service password-encryption ! hostname R3 ! ! memory-size iomem 10 no ip domain-lookup

! ! voice-port 1/1/0 ! voice-port 1/1/1 ! ! ! process-max-time 200 ! interface Ethernet0/0 no ip address shutdown ! interface Serial0/0 ip address 192.168.1.250 255.255.255.252 no ip mroute-cache no fair-queue clockrate 64000 ! interface Serial0/1 ip address 192.168.1.242 255.255.255.252 clockrate 64000 !

router bgp 300 no synchronization neighbor 192.168.1.241 remote-as 200 neighbor 192.168.1.249 remote-as 200 ! ip classless ! ! ! line con 0 logging synchronous line aux 0 line vty 0 4 login ! no scheduler allocate end


Current configuration: ! version 11.3

service timestamps debug uptime service timestamps log uptime no service password-encryption ! hostname R3 ! ! memory-size iomem 10 no ip domain-lookup ! ! voice-port 1/1/0 ! voice-port 1/1/1 ! ! ! process-max-time 200 ! interface Ethernet0/0 no ip address shutdown ! interface Serial0/0

ip address 192.168.1.250 255.255.255.252 no ip mroute-cache no fair-queue clockrate 64000 ! interface Serial0/1 ip address 192.168.1.242 255.255.255.252 clockrate 64000 ! router bgp 300 no synchronization neighbor 192.168.1.241 remote-as 200 neighbor 192.168.1.249 remote-as 200 ! ip classless ! ! ! line con 0 logging synchronous line aux 0 line vty 0 4 login !

no scheduler allocate end


Current configuration: ! version 12.1 service timestamps debug uptime service timestamps log uptime no service password-encryption ! hostname R4 ! ! ! ! ! ! ip subnet-zero no ip domain-lookup ! !

! ! interface Ethernet0 ip address 192.168.1.237 255.255.255.252 interface Serial0 ip address 192.168.1.246 255.255.255.252 no fair-queue ! interface Serial1 ip address 192.168.1.241 255.255.255.252 ! router bgp 200 neighbor 192.168.1.238 remote-as 200 neighbor 192.168.1.238 next-hop-self neighbor 192.168.1.242 remote-as 300 neighbor 192.168.1.245 remote-as 100 ! ip classless no ip http server ! ! line con 0 logging synchronous transport input none

line aux 0 line vty 0 4line vty 0 4 login ! end


Current configuration: ! version 12.1 service timestamps debug uptime service timestamps log uptime no service password-encryption ! hostname R5

! ! ! ! ! ! ip subnet-zero no ip domain-lookup ! ! ! ! interface Loopback0 ip address 192.168.196.1 255.255.255.0 interface Loopback1 ip address 192.168.197.1 255.255.255.0 ! interface Loopback2 ip address 192.168.198.1 255.255.255.0 ! interface Loopback3 ip address 192.168.199.1 255.255.255.0 ! interface Ethernet0

ip address 192.168.1.202 255.255.255.252 ! interface Serial0 no ip address shutdown no fair-queue ! interface Serial1 ip address 192.168.1.245 255.255.255.252 clockrate 64000 ! router eigrp 1 network 192.168.1.0 network 192.168.196.0 network 192.168.197.0 network 192.168.198.0 network 192.168.199.0 no auto-summary no eigrp log-neighbor-changes ! router bgp 100 no synchronization redistribute eigrp 100 neighbor 192.168.1.201 remote-as 100

neighbor 192.168.1.201 next-hop-self neighbor 192.168.1.246 remote-as 200 ! ip classless no ip http server ! ! line con 0 logging synchronous transport input none line aux 0 line vty 0 4 login ! end

R3#show ip bgp BGP table version is 58, local router ID is 192.168.1.250 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal Origin codes: i - IGP, e - EGP, ? - incomplete

Network Path

Next Hop

Metric LocPrf Weight

*> 192.168.1.200/30 192.168.1.241 200 100 ? * 100 ? 192.168.1.249 0 200

0

*> 192.168.1.244/30 192.168.1.241 200 100 ? * 100 ? 192.168.1.249 0 200

0

*> 192.168.1.252/30 192.168.1.241 200 100 ? * 100 ? 192.168.1.249 0 200

0

*> 192.168.192.0 200 100 ? * 100 ?

192.168.1.241

0

192.168.1.249

0 200

*> 192.168.192.0/21 192.168.1.241 * 100 i 192.168.1.249

0 200 100 i 0 200

*> 192.168.193.0 200 100 ? * 100 ?

192.168.1.241

0

192.168.1.249

0 200

*> 192.168.194.0 200 100 ? * 100 ?

192.168.1.241

0

192.168.1.249

0 200

*> 192.168.195.0 200 100 ? *

192.168.1.241

0

192.168.1.249

0 200

100 ? *> 192.168.196.0 200 100 ? * 100 ? Network Weight Path 192.168.1.241 0

192.168.1.249

0 200

Next Hop

Metric LocPrf

*> 192.168.197.0 200 100 ? * 100 ?

192.168.1.241

0

192.168.1.249

0 200

*> 192.168.198.0 200 100 ? * 100 ?

192.168.1.241

0

192.168.1.249

0 200

*> 192.168.199.0 200 100 ? * 100 ?

192.168.1.241

0

192.168.1.249

0 200


Network Weight Path

Next Hop

Metric LocPrf

* i192.168.1.200/30 192.168.1.237 0 100 ?

100

*> 100 ?

192.168.1.254

0

0

* i192.168.1.244/30 192.168.1.237 0 100 ? *> 100 ? 192.168.1.254 2195456

100

0

* i192.168.1.252/30 192.168.1.237 0 100 ? *> 100 ? 192.168.1.254 0

100

0

* i192.168.192.0 0 100 ? *> 100 ?

192.168.1.237

100

192.168.1.254

0

0

* i192.168.192.0/21 192.168.1.237 100 0 100 i *> i 192.168.1.254 0 0 100

* i192.168.193.0 0 100 ? *> 100 ?

192.168.1.237

100

192.168.1.254

0

0

* i192.168.194.0 0 100 ? *> 100 ?

192.168.1.237

100

192.168.1.254

0

0

* i192.168.195.0 0 100 ? *> 100 ?

192.168.1.237

100

192.168.1.254

0

0

* i192.168.196.0 0 100 ? *>

192.168.1.237

100

192.168.1.254

409600

0

100 ? Network Path Next Hop Metric LocPrf Weight

* i192.168.197.0 0 100 ? *> 100 ?

192.168.1.237

100

192.168.1.254

409600

0

* i192.168.198.0 0 100 ? *> 100 ?

192.168.1.237

100

192.168.1.254

409600

0

* i192.168.199.0 0 100 ? *> 100 ?

192.168.1.237

100

192.168.1.254

409600

0

Tip theo th ta ch cho php R5 qung b route tm tt thi cn tt c cc route thuc route tm tt ny s khng c qung co i cho AS khc, v ta c cu hnh :

R5(config-router)#aggregate-address 192.168.192.0 255.255.248.0 summary-only

Trn R5 ta thy cc route thuc mng tm tt 192.168.192.0/21 u b suppress tc n s khng oc qung co i cho AS 200 R5#show ip bgp BGP table version is 23, local router ID is 192.168.199.1 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal

Origin codes: i - IGP, e - EGP, ? - incomplete

Network Weight Path

Next Hop

Metric LocPrf

*>i192.168.1.200/30 192.168.1.201 100 0? *>i192.168.1.244/30 192.168.1.201 100 0? *>i192.168.1.252/30 192.168.1.201 100 0? s>i192.168.192.0 0? 192.168.1.201 0

0

2195456

0

100

*> 192.168.192.0/21 0.0.0.0 32768 i *i 192.168.1.201 192.168.1.201 0 100 0 0i 100

s>i192.168.193.0 0? s>i192.168.194.0 0? s>i192.168.195.0 0? s>i192.168.196.0 100 0? s>i192.168.197.0 100 0? s>i192.168.198.0 100 0? s>i192.168.199.0 100 0?

192.168.1.201

0

100

192.168.1.201

0

100

192.168.1.201

409600

192.168.1.201

409600

192.168.1.201

409600

192.168.1.201

409600

V ta thy trn R3 bng route ca BGP by gi i vi cc mng 192.168.192.0/24 cho n

192.168.199.0/24 u ch c mt ng i n AS 100.


Network Path

Next Hop


*> 192.168.1.200/30 192.168.1.241 200 100 ? * 100 ? 192.168.1.249

0

0 200

*> 192.168.1.244/30 192.168.1.241 200 100 ? * 100 ? 192.168.1.249 0 200

0

*> 192.168.1.252/30 192.168.1.241 200 100 ? * 100 ? 192.168.1.249 0 200

0

*> 192.168.192.0 200 100 ?

192.168.1.249

0

*> 192.168.192.0/21 192.168.1.241 200 100 i * 100 i 192.168.1.249 0 200

0

*> 192.168.193.0

192.168.1.249

0

200 100 ? *> 192.168.194.0 200 100 ? *> 192.168.195.0 200 100 ? *> 192.168.196.0 200 100 ? *> 192.168.197.0 200 100 ? *> 192.168.198.0 200 100 ? *> 192.168.199.0 200 100 ? 192.168.1.249 0

192.168.1.249

0

192.168.1.249

0

192.168.1.249

0

192.168.1.249

0

192.168.1.249

0

Tip theo ta s s dng aggregate route vi qung co nhng route c bit thi. Ta s s dng COMMUNITY

Ta s cu hnh cho R1, v R5 qung b cho cc router trong AS 200 bit l ch c route 192.168.192.0/21 mi c qung co ra cho AS khc cn cc route cn lai th khng. y ta s dng lnh access-list 101 permit ip host 192.168.192.0 host 255.255.248.0

Lnh ny ch ra l n ch cho php duy nht mng 192.168.192.0/21 che khng cho php cc mng thuc tm tt route ny


Current configuration: ! version 12.1 service timestamps debug uptime service timestamps log uptime no service password-encryption ! hostname R5 ! ! ! ! ! ! ip subnet-zero no ip domain-lookup ! ! ! ! interface Loopback0

ip address 192.168.196.1 255.255.255.0 interface Loopback1 ip address 192.168.197.1 255.255.255.0 ! interface Loopback2 ip address 192.168.198.1 255.255.255.0 ! interface Loopback3 ip address 192.168.199.1 255.255.255.0 ! interface Ethernet0 ip address 192.168.1.202 255.255.255.252 ! interface Serial0 ip address 192.168.1.245 255.255.255.252 no fair-queue clockrate 64000 ! interface Serial1 no ip address clockrate 64000 ! router eigrp 1 passive-interface Serial1

network 192.168.1.0 network 192.168.196.0 network 192.168.197.0 network 192.168.198.0 network 192.168.199.0 no auto-summary no eigrp log-neighbor-changes ! router bgp 100 no synchronization aggregate-address 192.168.192.0 255.255.248.0 redistribute eigrp 1 neighbor 192.168.1.201 remote-as 100 neighbor 192.168.1.201 next-hop-self neighbor 192.168.1.246 remote-as 200 neighbor 192.168.1.246 send-community neighbor 192.168.1.246 route-map COMMUNITY out ! ip classless no ip http server ! access-list 101 permit ip host 192.168.192.0 host 255.255.248.0 route-map COMMUNITY permit 1

match ip address 101 set community none ! route-map COMMUNITY permit 10 set community no-export ! ! line con 0 logging synchronous transport input none line aux 0 line vty 0 4 login ! end . R1#show runn Building configuration...

Current configuration : 1775 bytes ! version 12.2 service timestamps debug datetime msec service timestamps log datetime msec

no service password-encryption ! hostname R1 ! logging queue-limit 100 ! memory-size iomem 10 ip subnet-zero ! ! no ip domain lookup ! mpls ldp logging neighbor-changes ! ! ! ! ! ! ! ! no voice hpi capture buffer no voice hpi capture destination !

! mta receive maximum-recipients 0 ! ! ! ! interface Loopback0 ip address 192.168.192.1 255.255.255.0 ! interface Loopback1 ip address 192.168.193.1 255.255.255.0 ! interface Loopback2 ip address 192.168.194.1 255.255.255.0 ! interface Loopback3 ip address 192.168.195.1 255.255.255.0 ! interface Ethernet0/0 ip address 192.168.1.201 255.255.255.252 half-duplex ! interface Serial0/0 ip address 192.168.1.254 255.255.255.252

clockrate 64000 ! router eigrp 1 passive-interface Serial0/0 network 192.168.1.0 network 192.168.192.0 network 192.168.193.0 network 192.168.194.0 network 192.168.195.0 no auto-summary ! router bgp 100 no synchronization bgp log-neighbor-changes aggregate-address 192.168.192.0 255.255.248.0 redistribute eigrp 1 neighbor 192.168.1.202 remote-as 100 neighbor 192.168.1.202 next-hop-self neighbor 192.168.1.253 remote-as 200 neighbor 192.168.1.253 send-community neighbor 192.168.1.253 route-map COMMUNITY out no auto-summary ! no ip http server

ip classless ! ! ! access-list 101 permit ip host 192.168.192.0 host 255.255.248.0 !

route-map COMMUNITY permit 1 match ip address 101 set community none ! route-map COMMUNITY permit 10 set community no-export ! call rsvp-sync ! ! mgcp profile default ! dial-peer cor custom ! ! !

! line con 0 logging synchronous line aux 0 line vty 0 4 password cisco login ! ! end

Kt qu l trn cc router thuc AS 200 th tt c cc route u nhn c bnh thng tuy nhin th khi cc router trong AS 200 ny cp nht route cho AS 300 th n ch qung co mng 192.168.192.0/21 thi. Ta xem kt qu trn R2 thuc AS 200 v R3 thuc AS 300 R2#show ip route Codes: C - connected, S - static, I - IGRP, R - RIP, M mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA OSPF inter area N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area * - candidate default, U - per-user static route, o

- ODR P - periodic downloaded static route


B 192.168.192.0/24 [20/0] via 192.168.1.254, 00:03:36 B 192.168.193.0/24 [20/0] via 192.168.1.254, 00:03:36 B 192.168.194.0/24 [20/0] via 192.168.1.254, 00:03:36 B 192.168.195.0/24 [20/0] via 192.168.1.254, 00:03:36 B 192.168.196.0/24 [20/409600] via 192.168.1.254, 00:03:36 B 192.168.197.0/24 [20/409600] via 192.168.1.254, 00:03:36 B 192.168.198.0/24 [20/409600] via 192.168.1.254, 00:03:36 B 192.168.199.0/24 [20/409600] via 192.168.1.254, 00:03:36 192.168.1.0/24 is variably subnetted, 6 subnets, 2 masks B 192.168.1.0/24 [20/0] via 192.168.1.254, 00:03:36 C 192.168.1.236/30 is directly connected, Ethernet0 C C B 192.168.1.248/30 is directly connected, Serial0 192.168.1.252/30 is directly connected, Serial1 192.168.1.244/30 [20/2195456] via

192.168.1.254, 00:03:37 B 192.168.1.200/30 [20/0] via 192.168.1.254, 00:03:37 B 192.168.192.0/21 [20/0] via 192.168.1.254, 00:03:37 R2#show ip bgp BGP table version is 124, local router ID is 192.168.1.253 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal Origin codes: i - IGP, e - EGP, ? - incomplete

Network Weight Path *> 192.168.1.0 100 ? *i ?

Next Hop

Metric LocPrf

192.168.1.254

0

192.168.1.237

0

100

0 100

* i192.168.1.200/30 192.168.1.237 0 100 ? *> 100 ? 192.168.1.254 0

100

0

* i192.168.1.244/30 192.168.1.237 0 100 ? *> 100 ? 192.168.1.254 2195456

100

0

* i192.168.1.252/30 192.168.1.237 0 100 ? *> 100 ? 192.168.1.254 0

100

0

*> 192.168.192.0

192.168.1.254

0

0 100 ? *i 100 ? 192.168.1.237 409600 100 0

*> 192.168.192.0/21 192.168.1.254 0 100 i *i i 192.168.1.237 100

0

0 100

*> 192.168.193.0 0 100 ? *i 100 ?

192.168.1.254

0

192.168.1.237

409600

100

0

*> 192.168.194.0 0 100 ? *i 100 ?

192.168.1.254

0

192.168.1.237

409600

100

0

*> 192.168.195.0 0 100 ? *i 100 ? Network Path

192.168.1.254

0

192.168.1.237

409600

100

0

Next Hop


*> 192.168.196.0 192.168.1.254 409600 0 100 ? *i ? 192.168.1.237 0 100 0 100

*> 192.168.197.0 192.168.1.254 409600 0 100 ? *i ? 192.168.1.237 0 100 0 100

*> 192.168.198.0 192.168.1.254 409600 0 100 ? *i 192.168.1.237 0 100 0 100

? *> 192.168.199.0 192.168.1.254 409600 0 100 ? *i ? 192.168.1.237 0 100 0 100


Network Path

Next Hop


*> 192.168.192.0/21 192.168.1.241 200 100 i

0

R3#show ip route Codes: C - connected, S - static, I - IGRP, R - RIP, M mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA OSPF inter area N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP

i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * candidate default U - per-user static route, o - ODR


192.168.1.0/30 is subnetted, 2 subnets C C 192.168.1.248 is directly connected, Serial0/0 192.168.1.240 is directly connected, Serial0/1

B 192.168.192.0/21 [20/0] via 192.168.1.241, 00:04:11

By gi ta s s dng ip prefix-list thay cho accesslist kt qu s ging nh trng hp trn ta xem cu hnh trn R1 nh sau

R1#show run Building configuration...

Current configuration : 1846 bytes !

version 12.2 service timestamps debug datetime msec service timestamps log datetime msec no service password-encryption ! hostname R1 ! logging queue-limit 100 ! memory-size iomem 10 ip subnet-zero ! ! no ip domain lookup ! mpls ldp logging neighbor-changes ! ! ! ! ! ! ! !

no voice hpi capture buffer no voice hpi capture destination ! ! mta receive maximum-recipients 0 ! ! ! ! interface Loopback0 ip address 192.168.192.1 255.255.255.0 ! interface Loopback1 ip address 192.168.193.1 255.255.255.0 ! interface Loopback2 ip address 192.168.194.1 255.255.255.0 ! interface Loopback3 ip address 192.168.195.1 255.255.255.0 ! interface Ethernet0/0 ip address 192.168.1.201 255.255.255.252 half-duplex

! interface Serial0/0 ip address 192.168.1.254 255.255.255.252 clockrate 64000 ! router eigrp 1 passive-interface Serial0/0 network 192.168.1.0 network 192.168.192.0 network 192.168.193.0 network 192.168.194.0 network 192.168.195.0 no auto-summary ! router bgp 100 no synchronization bgp log-neighbor-changes aggregate-address 192.168.192.0 255.255.248.0 redistribute eigrp 1 neighbor 192.168.1.202 remote-as 100 neighbor 192.168.1.202 next-hop-self neighbor 192.168.1.253 remote-as 200 neighbor 192.168.1.253 send-community neighbor 192.168.1.253 route-map COMMUNITY out

no auto-summary ! no ip http server ip classless ! ! ! ip prefix-list summary seq 1 permit 192.168.192.0/21 ! access-list 101 permit ip host 192.168.192.0 host 255.255.248.0 ! route-map COMMUNITY permit 1 match ip address prefix-list summary set community none ! route-map COMMUNITY permit 10 set community no-export ! ! call rsvp-sync ! ! mgcp profile default

! dial-peer cor custom ! ! ! ! line con 0 logging synchronous line aux 0 line vty 0 4 password cisco login ! ! end

Tip theo ta s s dng suppress-map trong aggregate route Cc route nm trong route map u b nh giu l ch s Tc n s khng c qung b ra AS bn ngoi Ta s cu hnh cho R1 ch cho php qung co route 192.168.192.0 ,192.168.193.0,192.168.194.0 cn tt c cc route cn li u b suppress khng c qung co ra bn ngoi Tng t i vi R5 ch c qung co mng 192.168.196.0, 192.168.197.0,192.168.198.0

Cn route 192.168.195.0 v 192.168.199.0 s khng c qung co ra bn ngoi bi cc router trong AS 100 R1#show runn Building configuration...

Current configuration : 1946 bytes ! version 12.2 service timestamps debug datetime msec service timestamps log datetime msec no service password-encryption ! hostname R1 ! logging queue-limit 100 ! memory-size iomem 10 ip subnet-zero ! ! no ip domain lookup ! mpls ldp logging neighbor-changes !

! ! ! ! ! ! ! no voice hpi capture buffer no voice hpi capture destination ! ! mta receive maximum-recipients 0 ! ! ! ! interface Loopback0 ip address 192.168.192.1 255.255.255.0 ! interface Loopback1 ip address 192.168.193.1 255.255.255.0 ! interface Loopback2 ip address 192.168.194.1 255.255.255.0

! interface Loopback3 ip address 192.168.195.1 255.255.255.0 ! interface Ethernet0/0 ip address 192.168.1.201 255.255.255.252 half-duplex ! interface Serial0/0 ip address 192.168.1.254 255.255.255.252 clockrate 64000 ! router eigrp 1 passive-interface Serial0/0 network 192.168.1.0 network 192.168.192.0 network 192.168.193.0 network 192.168.194.0 network 192.168.195.0 no auto-summary ! router bgp 100 no synchronization bgp log-neighbor-changes

aggregate-address 192.168.192.0 255.255.248.0 suppress-map suppress redistribute eigrp 1 neighbor 192.168.1.202 remote-as 100 neighbor 192.168.1.202 next-hop-self neighbor 192.168.1.253 remote-as 200 neighbor 192.168.1.253 send-community neighbor 192.168.1.253 route-map COMMUNITY out no auto-summary ! no ip http server ip classless ! ! ! ip prefix-list summary seq 1 permit 192.168.192.0/21 ! access-list 1 permit 192.168.196.0 0.0.3.255 access-list 1 permit 192.168.195.0 0.0.0.255 access-list 101 permit ip host 192.168.192.0 host 255.255.248.0 ! route-map suppress permit 1 match ip address 1 !

route-map COMMUNITY permit 1 match ip address prefix-list summary set community none ! route-map COMMUNITY permit 10 set community no-export ! ! call rsvp-sync ! ! mgcp profile default ! dial-peer cor custom ! ! ! ! line con 0 logging synchronous line aux 0 line vty 0 4 password cisco login

! ! end


Current configuration: ! version 12.1 service timestamps debug uptime service timestamps log uptime no service password-encryption ! hostname R5 ! ! ! ! ! ! ip subnet-zero no ip domain-lookup !

! ! ! interface Loopback0 ip address 192.168.196.1 255.255.255.0 interface Loopback1 ip address 192.168.197.1 255.255.255.0 ! interface Loopback2 ip address 192.168.198.1 255.255.255.0 ! interface Loopback3 ip address 192.168.199.1 255.255.255.0 ! interface Ethernet0 ip address 192.168.1.202 255.255.255.252 ! interface Serial0 ip address 192.168.1.245 255.255.255.252 no fair-queue clockrate 64000 ! interface Serial1 no ip address

clockrate 64000 ! router eigrp 1 passive-interface Serial1 network 192.168.1.0 network 192.168.196.0 network 192.168.197.0 network 192.168.198.0 network 192.168.199.0 no auto-summary no eigrp log-neighbor-changes ! router bgp 100 no synchronization aggregate-address 192.168.192.0 255.255.248.0 suppress-map suppress redistribute eigrp 1 neighbor 192.168.1.201 remote-as 100 neighbor 192.168.1.201 next-hop-self neighbor 192.168.1.246 remote-as 200 neighbor 192.168.1.246 send-community neighbor 192.168.1.246 route-map COMMUNITY out ! ip classless

no ip http server ! ! ip prefix-list summary seq 1 permit 192.168.192.0/21 access-list 1 permit 192.168.192.0 0.0.3.255 access-list 1 permit 192.168.199.0 0.0.0.255 access-list 101 permit ip host 192.168.192.0 host 255.255.248.0 route-map suppress permit 1 match ip address 1 ! route-map COMMUNITY permit 1 match ip address prefix-list summary set community none ! route-map COMMUNITY permit 10 set community no-export ! ! line con 0 logging synchronous transport input none line aux 0 line vty 0 4

login ! end

Ta thy ch nhng route 192,193,194,195,199 bi suppress trong R5 by gi ta s xem bng route ca R5 c ch s R5#show ip bgp BGP table version is 25, local router ID is 192.168.199.1 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal Origin codes: i - IGP, e - EGP, ? - incomplete

Network Weight Path *> 192.168.1.0 ?

Next Hop

Metric LocPrf

0.0.0.0

0

32768

*>i192.168.1.200/30 192.168.1.201 100 0 ? *>i192.168.1.244/30 192.168.1.201 100 0 ? *>i192.168.1.252/30 192.168.1.201 100 0 ? s> 192.168.192.0 32768 ? si 192.168.1.201

0

2195456

0

409600

192.168.1.201

0

100

0

?

*> 192.168.192.0/21 0.0.0.0 32768 i *i 192.168.1.201 192.168.1.201 0 100 409600 0 i

s> 192.168.193.0 32768 ? si

192.168.1.201 192.168.1.201

0

100 409600

0 ?

s> 192.168.194.0 32768 ? si

192.168.1.201 192.168.1.201

0

100 409600

0 ?

s> 192.168.195.0 32768 ? *> 192.168.196.0 32768 ? *> 192.168.197.0 32768 ? *> 192.168.198.0 32768 ? s> 192.168.199.0 ?

0.0.0.0

0

0.0.0.0

0

0.0.0.0

0

0.0.0.0

0

32768

Ta xem bng route ca R2 ta thy 192,193,194 ch c mt route i theo ng c next hop 192.168.1.254 V ta 196,197,198 ch c mt route i theo ng c next hop l 192.168.1.237 Cn R4 cng tng t R2#show ip bgp BGP table version is 11, local router ID is 192.168.1.253 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal

Origin codes: i - IGP, e - EGP, ? - incomplete

Network Weight Path *> 192.168.1.0 100 ? *i ?

Next Hop

Metric LocPrf

192.168.1.254

0

192.168.1.237

0

100

0 100

* i192.168.1.200/30 192.168.1.237 0 100 ? *> 100 ? 192.168.1.254 0

100

0

* i192.168.1.244/30 192.168.1.237 0 100 ? *> 100 ? 192.168.1.254 2195456

100

0

* i192.168.1.252/30 192.168.1.237 0 100 ? *> 100 ? 192.168.1.254 0

100

0

*> 192.168.192.0 0 100 ?

192.168.1.254

0

* i192.168.192.0/21 192.168.1.237 0 100 i *> i 192.168.1.254 0

100

0 100

*> 192.168.193.0 0 100 ? *> 192.168.194.0 0 100 ? * i192.168.196.0 0 100 ?

192.168.1.254

0

192.168.1.254

0

192.168.1.237

0

100

* i192.168.197.0 0 100 ? * i192.168.198.0 0 100 ?

192.168.1.237

0

100

192.168.1.237

0

100

R4# show ip bgp BGP table version is 179, local router ID is 192.168.1.246 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal Origin codes: i - IGP, e - EGP, ? - incomplete

Network Weight Path * i192.168.1.0 100 ? *> 100 ?

Next Hop

Metric LocPrf

192.168.1.238

100

0

192.168.1.245

0

0

*> 192.168.1.200/30 192.168.1.245 0 100 ? *i ? 192.168.1.238 0 100 0 100

*> 192.168.1.244/30 192.168.1.245 0 100 ? *i 100 ? 192.168.1.238 2195456 100 0

*> 192.168.1.252/30 192.168.1.245 0 100 ? *i ? 192.168.1.238 0 100 0 100

* i192.168.192.0

192.168.1.238

0

100

0 100 ? *> 192.168.192.0/21 192.168.1.245 0 100 i *i i 192.168.1.238 0 100 0 100

* i192.168.193.0 0 100 ? * i192.168.194.0 0 100 ? *> 192.168.196.0 0 100 ? *> 192.168.197.0 0 100 ? *> 192.168.198.0 0 100 ?

192.168.1.238

0

100

192.168.1.238

0

100

192.168.1.245

0

192.168.1.245

0

192.168.1.245

0

Do ta thit lp community no-export cho cc route c qung b i nn trn R3 s khng c cc route ny m ch c route tm tt do lnh aggregation


Network Path

Next Hop


*> 192.168.192.0/21 192.168.1.241 200 100 i * 100 i 192.168.1.249 0 200

0

3. Cu hnh cho s 3(cu hnh v Local Preference, MED, backdoor)

Ta s cu hnh Local Preference trc Ta cu hnh cho R5 v R6 thuc AS 30 chn cc route i n AS 50 v AS 75. i vi cc route i n AS 50 th ta s cho i theo ng qua R5 v cc route n AS 75 th ta s cho i theo ng R6 Ta s dng cu hnh nh sau: i vi R5 th cc route i n AS 50 th c thit lp Local Preference l 200 cn cc route cn li th c gi tr mc nh l 100 do d router s chn route c Local

Preference cao hn Tng t th trn R6 ta s thit lp cc route i n AS 75 c Local Prefrnc l 400, cc route cn li l 100 R1#show run Building configuration...

Current configuration: ! version 11.3 service timestamps debug uptime service timestamps log uptime no service password-encryption ! hostname R1 ! ! memory-size iomem 10 no ip domain-lookup ! ! ! ! process-max-time 200 !

interface Loopback0 ip address 10.20.0.1 255.255.0.0 ! interface Loopback1 ip address 172.17.0.1 255.255.0.0 ! interface Loopback2 no ip address ! interface Loopback3 ip address 192.168.50.1 255.255.255.0 ! interface Ethernet0/0 ip address 10.10.10.1 255.255.255.248 ! interface Serial0/0 ip address 192.168.11.1 255.255.255.0 no ip mroute-cache no fair-queue ! router rip network 10.0.0.0 network 172.17.0.0 network 172.29.0.0

network 192.168.50.0 ! router bgp 50 redistribute rip neighbor 10.10.10.2 remote-as 75 neighbor 10.10.10.3 remote-as 100 neighbor 10.10.10.4 remote-as 100 ip classless

line con 0 logging synchronous line aux 0 line vty 0 4 login ! no scheduler allocate end


Current configuration : 1156 bytes ! version 12.2 service timestamps debug datetime msec service timestamps log datetime msec no service password-encryption ! hostname R2 ! logging queue-limit 100 ! memory-size iomem 10 ip subnet-zero ! ! no ip domain lookup ! mpls ldp logging neighbor-changes ! ! !

! ! ! ! ! no voice hpi capture buffer no voice hpi capture destination ! ! mta receive maximum-recipients 0 ! ! ! ! interface Loopback0 ip address 172.18.0.1 255.255.0.0 ! interface Loopback1 ip address 192.168.75.1 255.255.255.0 ! interface Ethernet0/0 ip address 10.10.10.2 255.255.255.248 half-duplex interface Serial0/0

ip address 192.168.11.2 255.255.255.0 clockrate 64000 no fair-queue ! ! router rip network 172.18.0.0 network 192.168.75.0 ! router bgp 75 synchronization bgp log-neighbor-changes network 172.17.0.0 redistribute rip neighbor 10.10.10.1 remote-as 50 neighbor 10.10.10.3 remote-as 100 neighbor 10.10.10.4 remote-as 100 no auto-summary ! ip http server ip classless ! ! !

! ! call rsvp-sync ! ! mgcp profile default ! dial-peer cor custom ! ! ! ! line con 0 logging synchronous line aux 0 line vty 0 4 ! ! end


Current configuration: ! version 11.3 service timestamps debug uptime service timestamps log uptime no service password-encryption ! hostname R4 ! ! memory-size iomem 10 no ip domain-lookup ! ! voice-port 1/1/0 ! voice-port 1/1/1 ! ! !

process-max-time 200 ! interface Ethernet0/0 ip address 10.10.10.4 255.255.255.248 ! interface Serial0/0 ip address 192.168.1.26 255.255.255.252 no ip mroute-cache no fair-queue ! interface Serial0/1 ip address 192.168.1.9 255.255.255.252 ! ! router bgp 100 neighbor 10.10.10.1 remote-as 50 neighbor 10.10.10.2 remote-as 75 neighbor 192.168.1.10 remote-as 30 neighbor 192.168.1.25 remote-as 100 neighbor 192.168.1.25 next-hop-self ! ip classless ! !

line con 0 logging synchronous line aux 0 line vty 0 4 login ! no scheduler allocate end


Current configuration: ! version 12.1 service timestamps debug uptime service timestamps log uptime no service password-encryption

! hostname R5 ! ! ! ! ! ! ip subnet-zero no ip domain-lookup ! ! ! ! interface Loopback0 ip address 192.168.2.1 255.255.255.0 interface Loopback1 ip address 192.168.100.1 255.255.255.0 ! interface Loopback2 ip address 172.29.1.1 255.255.255.0 ! interface Ethernet0 ip address 192.168.1.17 255.255.255.252

! interface Serial0 no ip address no fair-queue clockrate 64000 ! interface Serial1 ip address 192.168.1.14 255.255.255.252 clockrate 64000 ! router ospf 1 log-adjacency-changes network 172.29.1.0 0.0.0.255 area 0 network 192.168.1.16 0.0.0.3 area 0 network 192.168.2.0 0.0.0.255 area 0 network 192.168.100.0 0.0.0.255 area 0 ! router bgp 30 no synchronization redistribute ospf 1 neighbor 192.168.1.13 remote-as 100 neighbor 192.168.1.13 route-map PREF in neighbor 192.168.1.13 filter-list 1 out neighbor 192.168.1.18 remote-as 30

neighbor 192.168.1.18 next-hop-self ! ip classless no ip http server ip as-path access-list 1 permit ^$ ip as-path access-list 2 permit _50$ ! route-map PREF permit 10 match as-path 2 set local-preference 200 ! route-map PREF permit 20 ! line con 0 logging synchronous transport input none line aux 0 line vty 0 4 ! end R4#show runn Building configuration...

Current configuration:

! version 11.3 service timestamps debug uptime service timestamps log uptime no service password-encryption ! hostname R4 ! ! memory-size iomem 10 no ip domain-lookup ! ! voice-port 1/1/0 ! voice-port 1/1/1 ! ! ! process-max-time 200 ! interface Ethernet0/0 ip address 10.10.10.4 255.255.255.248 !

interface Serial0/0 ip address 192.168.1.26 255.255.255.252 no ip mroute-cache no fair-queue ! interface Serial0/1 ip address 192.168.1.9 255.255.255.252 ! router isis ! router bgp 100 neighbor 10.10.10.1 remote-as 50 neighbor 10.10.10.2 remote-as 75 neighbor 192.168.1.10 remote-as 30 neighbor 192.168.1.2

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Bài Viết BGP