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Bi 5. Theo di Mng t xa - RMON

BI 5. THEO DI MNG T XA(RMON)

Khi kt ni cc mng cc b thnh mng ln hn, rt cn c cc c ch cho nh qun l bit tng tn v cc nt mng. H thng theo di MIB t xa (RMON) cung cp cc tnh nng nh th. RMON l mt thnh phn b sung quan trng cho cc chuNn SNMP nhng khng lm thay i ni dung vn c ca cc chuNn ny. V bn cht, RMON l mt ch nh k thut c bit i vi MIB v c SNMP h tr. C hai phin bn RMON: RMON1 v RMON2 Cc chuNn lin quan ti RMONRFC Thi gian Tiu 1513 9/1993 M rng Token Ring truy xut theo di MIB t xa 1757 2/1995 Remote Network Monitoring Management Information Base (RMON1) Remote Network Monitoring Management Information Base, Version 2, s dng 2021 1/1997 SMIv2 (RMON 2) 2074 1/1997 Cc tn chuNn trong giao thc RMON

I. Tng quan v RMONI.1 Cc nguyn tc c bn RMON l mt chc nng c bit ca MIB cng vi mt thc th qun l ng vai tr mt agent thu thp v qun l mt MIB (c h tr RMON, ni tt l RMON MIB). Thc th qun l ny thng tr trong NE, gi l remote monitor hoc probe, n theo di hiu nng v hot ng ca mt phn on mng gnh nng cho trm qun l v cc i din qun l khc. Ni cch khc, RMON da hon ton vo kin trc sn c ca SNMP, ch c mt s b sung duy nht l probe theo di t xa m n hoc l mt thit b mang chc nng ny, hoc l mt thit b c km theo chc nng ny. gim

Nguyn Nam Hng B mn K thut my tnh v Mng i hc Thy li

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I.2 Mc tiu thit k RMON (RFC 1757) Hot ng ngoi tuyn: RMON MIB cho php cu hnh probe lin tc thu thp tnh hnh hot ng, li, d liu cu hnh c lp vi vic nh qun l c trc tip qun l thit b hay khng. (L do ???) Ch ng theo di: Nu probe c ti nguyn, n s c cu hnh lin tc kho st v nm bt tnh hnh hot ng vi mc tiu chnh xc v kp thi bo co tnh hnh cho thc th qun l. Pht hin v bo co: D lm vic trong ch th ng th probe vn c th c cu hnh nhn din tng tnh hung c th, nm bt hu ht cc s c v nghn. Ngay khi nhn din c vn , probe thc hin ghi chp v bo co. D liu gi tr gia tng: Probe c th c cu hnh phn tch, phn loi, t rt trch thng tin cn thit t d liu thu thp Phc v nhiu nh qun l: Mt probe c th c cu hnh phc v nhiu trm qun l. H thng h tr RMON bao gm: Mt trm qun l. Cc RMON probe, mi RMON probe gm: o Mt RMON MIB c th cho h thng RMON. o Mt agent I.3 Cu trc ca RMON MIB - RMON MIB bao gm mt tp hp cc nhm i tng. - Mi nhm i tng gm hai loi d liu: d liu iu khin v d liu thng k. - D liu iu khin ch ra: ra sao (HOW), v lc no (WHEN) th thu thp d liu thng k. - Cu trc ca d liu thng k c thu thp l ty thuc vo cch thit lp ca phng php thng k.Nguyn Nam Hng B mn K thut my tnh v Mng i hc Thy li

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- Hai loi d liu ny c th cng hoc khc bng vi nhau. - Nu bng c ct status, c ngha l bng ny cho php c, ghi, xa, to dng mi. Ct status c kiu d liu tng ng vi RowStatus trong SNMP SMIv2, nhng tp gi tr bao gm: +valid (1). Cho bit d liu ca dng tng ng l hp l. +createRequest (2). Cho bit i tng ang c to. Khi hon thin vic to i tng, gi tr ny s tr thnh underCreation hoc valid. +underCreation (3). Cho bit i tng ang c xy dng, thit lp, cp nht, d liu trong bng cha y hoc cha hp l. +invalid (4). Gi tr ny nh du tnh khng hp l ca dng d liu tng ng.Hnh v d

Nu s dng hai bng, iu khin v d liu, ring bit th gia chng lun c thit lp quan h. C th tn ti trng hp mt dng ca bng iu khin c nh x ti nhiu dng trong bng d liu. V d, quan h gia mt giao tip mng vi mt host hoc nhiu host gn lin vi giao tip .

II. Gii thiu RMON1:Phin bn u tin ra i nm 1991, tr thnh chuNn nm 1995.Nguyn Nam Hng B mn K thut my tnh v Mng i hc Thy li Trang 3/23


RMON MIB bao gm cc nhm i tng sau: Statistics: cc thng tin thng k v probe thng qua vic theo di mt giao tip Ethernet. History: nh k ghi li cc mu d liu thng k ly t nhm Statistics Alarm: cho php nh qun l thit lp cc ngng bo ng v khong thi gian thu thp d liu v hiu nng thi hnh. Host: cha d liu o m thng tin i v n cc host trong mng con. HostTopN: Cha d liu thng k v N host c sp xp theo th t; cu trc th t v ni dung sp xp do nh qun l ch ra. Matrix: trnh by d liu giao vn cho tng cp host trong mng con. Filter: Cho php probe quan st d liu giao vn mt cch c chn lc da theo tiu chuNn do trm qun l ra. Packet capture: chn bt d liu theo tiu chuNn ca trng filter. Event: ghi chp tt c cc s kin ti probe. II.1 Nhm Statistics: y l mt bng m mi dng cha m t v mt giao tip Ethernet. Thng tin iu khin v d liu c gp chung . Cc i tng d liu thuc nhm ny cung cp mt cch nhn tng qut v tng trng thi kt ni ethernet vi tng RMON probe. Cc tham s trong bng ny gm: + etherStatsIndex. Ch s hng, nguyn, mi hng theo di mt giao tip Ethernet ca thit b. + etherStatsDataSource. Nhn dng giao tip m dng ny ang qun l. + etherStatsDropEvents. S lng s kin khin RMON probe phi hy b gi tin do thiu ti nguyn cn thit. + etherStatsOctets. S octet d liu trong cc gi tin hng nhn. + etherStatsPkts. S gi d liu nhn (tt c). + etherStatsBroadcastPkts. S gi broadcast hp l nhn c. + etherStatsMulticastPkts. S gi multicast hp l nhn c.


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+ etherStatsCRCAlignErrors. S gi tin c chiu di t 64 n 1518 octet nhn c nhng pht hin trng CRC sai, hoc li khc. + etherStatsUndersizePkts. S gi d liu c chiu di nh hn 64 octet nhn c. + etherStatsOversizePkts. S gi d liu nhn c chiu di ln hn 1518 octet. + etherStatsFragments. S gi d liu ngn hn 64 octet nhng sai FCS hoc s bit khng chia ht cho 8 (tc, s octet khng nguyn, alignment error). + etherStatsJabbers. S gi tin nhn c c chiu di hn 1518 octet v sai FCS hoc s bit khng chia ht cho 8. + etherStatsCollisions. D on tng s ln va chm. + etherStatsPkts64Octets. Tng s gi tin 64 octet nhn (c s gi li). + etherStatsPkts65to127Octets. Tng s gi tin 65 octet n 127 octet nhn (c s gi li). + etherStatsPkts128to255Octets. Tng s gi tin 128 octet n 255 octet nhn (c s gi li). + etherStatsPkts256to511Octets. Tng s gi tin 128 octet n 511 octet nhn (c s gi li). + etherStatsPkts512to1023Octets. Tng s gi tin 512 octet n 1023 octet nhn (c s gi li). + etherStatsPkts1024to1518Octets. Tng s gi tin 1024 octet n 1518 octet nhn (c s gi li). + etherStatsOwner. Mt chui dng nhn din thc th s hu giao tip m dng ny qun l. + etherStatsStatus. Trng thi hot ng ca giao tip. II.2 Nhm History: Nhm ny gm 2 bng: bng iu khin v bng d liu. Bng iu khin:


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Mi dng trong bng iu khin theo di d liu iu khin mt giao tip mng ca probe, vi cc tham s sau: + historyControlIndex. Ch s duy nht, nguyn, phn bit dng. + historyControlDataSource. nh danh kiu OBJECT IDENTIFIER ch ra ngun gc d liu. + historyControlBucketsRequested. S nguyn, biu th khong thi gian ly mu d liu. + historyControlBucketsGranted. S nguyn biu din khong cch gia cc ln ly mu d liu. + historyControlInterval. Thi gian ly mu i vi tng bucket. + historyControlOwner. Mt chui nhn din thc th lin quan ti dng. + historyControlStatus. Trng thi ca dng Bng d liu Cha cc mu d liu v d liu truyn gi ca mt min mng con Ethernet rng vi mt khong thi gian ly mu c th v khong thi gian ny c ch ra trong bng iu khin. + etherHistoryIndex. Ch s nguyn phn bit cc dng trong bng cc d liu ly mu. + etherHistorySampleIndex. Ch s nguyn phn bit d liu ly mu ca dng ny lin quan ti dng no ca bng iu khin. + eitherHistoryIntervalStart. Gi tr sysUpTime, ch thi im bt u khong thi gian ly mu. + etherHistoryDropEvents. S lng s kin lm cho RMON probe phi hy b gi tin do thiu ti nguyn. + etherHistoryOctets. S octet d liu nhn c, k c trong cc gi tin hng. + etherHistoryPkts. S gi tin nhn trong thi gian ly mu, k c cc gi tin hng.


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+ etherHistoryBroadcastPkts. S gi tin broadcast c chp nhn trong khong thi gian ly mu. + etherHistoryMulticastPkts. S gi tin multicast packets c chp nhn trong khong thi gian ly mu. + etherHistoryCRCAlignErrors. S gi tin d liu nhn trong thi gian ly mu c chiu di t 64 n 1518 octet nhng c li CRC hoc li khc. + etherHistoryUndersizePkts. S gi tin d liu nhn trong thi gian ly mu c chiu di nh hn 64 octet. + etherHistoryOversizePkts. S gi d liu nhn trong thi gian ly mu, c chiu di ln hn 1518 octet. + etherHistoryFragments. S gi tin d liu nhn trong thi gian ly mu, c chiu di nh hn 64 octet nhng cha li FCS hay li khc. + etherHistoryJabbers. S gi tin d liu nhn trong thi gian ly mu, c chiu di ln hn 1518 octet, nhng cha li FCS hay li khc. +etherHistoryCollisions. c tnh s ln va chm xy ra (collision) trong phn on Ethernet trong khong thi gian ly mu. + etherHistoryUtilization. c tnh gi tr % trung bnh tt nht trong khong thi gian ly mu v s tn dng ca tng vt l trong giao tip ny. II.3. Nhm Alarm: Bao gm mt tp hp cc gii hn (ngng) m da vo pht sinh cc cnh bo v giao vn mng. traffic. Nguyn l lm vic: RMON probe nh k ly mu thng k v so snh vi cc ngng thit lp bi nh qun l. Nu mu t ti hoc vt gii hn, th mt cnh bo c sinh ra. RMON probe ch theo di c cc ngng c kiu primitive ASN.1 (INTEGER, Counter, Gauge, hay TimeTicks). Hai gi tr ngng c nh ngha gm: rising v falling. Bt c gi tr ca i tng ly mu no ri vo khong gia hai ngng ny u c coi l vi phm v gy ra bo ng.Nguyn Nam Hng B mn K thut my tnh v Mng i hc Thy li Trang 7/23


Nhm ny gm mt bng alarmTable, c cu hnh bi trm qun l thng qua ct status. Mi dng ca bng biu din mt bin cn theo di v cc tham s sau: + alarmIndex. Mt s nguyn phn bit vi cc dng trong bng alarm. + alarmInterval. Khong thi gian tnh bng giy m d liu ly mu c em so snh vi hai ngng rising v falling. + alarmVariable. Tn bin (kiu object identifier) cn ly mu. + alarmSampleType. Phng php ly mu: Hoc gi tr chnh xc, hoc dung sai. + alarmValue. Gi tr thng k trong ln ly mu trc. + alarmStartupAlarm. Cnh bo u tin c gi i khi dng ny chuyn trng thi (row status) thnh valid. + alarmRisingThreshold. Gi tr ngng thng k. + alarmFallingThreshold. Gi tr ngng thng k. + alarmRisingEventIndex. Ch s s kin trong bng s kin khi xy ra mt ngng rising. + alarmFallingEventIndex. Ch s s kin trong bng s kin khi xy ra mt ngng Falling. + alarmOwner. Thc th c trch nhim cu hnh bng. + alarmStatus. Trng thi ca dng trong bng.Nguyn Nam Hng B mn K thut my tnh v Mng i hc Thy li Trang 8/23


II.4 Nhm Host: Nhm ny phn nh cc host mi c b sung vo phn on do RMON probe theo di. Nhm ny kt hp vi mt danh sch a ch ngun v ch m chng c trch ra t cc gi tin c chp nhn. Vi mi cp a ch ny, nhm host s sn sinh mt tp thng k. Nhm gm 3 bng: + Bng iu khin host (host control). + Bng host (host), v + Bng theo di thi gian lm vic ca host (host time). Bng Host control theo di cc giao tip m t ni vi cc host mi c pht hin. Mi dng ca bng biu din mt giao tip mng ca probe, vi cc tham s nh sau: + hostControlIndex. Ch s dng phn bit vi cc dng khc. + hostControlDataSource. i tng nhn din ngun d liu bng host entry. Ngun c th l bt c giao tip no vi RMON probe. (Quan h) + hostControlTableSize. S lng dng d liu lin quan ti host trong bng host time. (Quan h). + hostControlLastDeleteTime. Thi gian h thng ch ra trong bin sysUpTime ca nhm system trong SNMP MIB, l thi im sau cng khi dng b xa khi bng host control. Gi tr zero ch ra rng khng c dng no b xa. + hostControlOwner. Thc th c ngha v cu hnh bng ny. + hostControlStatus. Trng thi ca dng. Bng host: mi a ch chim mt dng. Bng ny thc hin ch s ha theo a ch host v cha mt s d liu giao vn n v i khi host: + hostAddress. a ch vt l ca host.


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+ hostCreationOrder. Trt t quan h theo thi gian khi to host ny. Gi tr ny trong phm vi t 1 n N, vi N l gi tr ca hostControlTableSize trong bng host control. + hostIndex. Ch s ca tp d liu thng k v host. (quan h mt nhiu). Gi tr ca i tng ny ph hp vi hostControlIndex ca mt (hoc nhiu) trong s cc dng trong bng host control. + hostInPkts. S gi tin lin quan ti host truyn nhn thnh cng k t khi host c qun l bi bng host. + hostOutPkts. Tng s gi tin, k c cc gi hng, truyn bi host ny k t khi n c qun l bi bng host. + hostInOctets. Tng s gi tin c truyn ti host ny k t khi host c qun l bi bng host. + hostOutOctets. Tng s octet truyn bi host ny, tnh t khi n c qun l bi bng host. + hostOutErrors. S gi tin m host ny truyn hng k t khi host c qun l bi bng host. + hostOutBroadCastPkts. S gi tin mang a ch broadcast m host ny truyn ra c chp nhn, k t khi host c qun l bi bng host. + hostMultiCastPkts. S gi tin mang a ch multicast m host ny truyn ra c chp nhn, k t khi host c qun l bi bng host. Bng host time: c cha cng mt tp host, cng cch thc t chc, d liu v nh dng d liu nh bng host. Tuy nhin, bng ny li c ch s ha theo hostTimeCreationOrder, l trt t theo thi gian m cc host c pht hin ra bi probe (Bng host sp xp theo a ch host). Bng ny c s dng theo hai kha cnh quan trng. + Mt l, cho php download nhanh trong trng hp bng ny ln, bi v ch s ca bng ny t ng nh t 1 n N (N l kch thc ca bng), cho php ng gi cc bin thnh cc SNMP PDU v nh s tun t nhiu gi.


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+ Hai l, gip RMON probe d dng pht hin ra cc host mi (bng php so snh) so vi ln truy vn trc. + hostTimeAddress. a ch vt l ca host. + hostTimeCreationOrder. Trt t quan h theo thi gian khi to ca host. Gi tr ny gia 1 v N m N bng hostControlTableSize trong bng host control. + hostTimeIndex. Tp d liu thng k v host. Gi tr ca i tng ny phi ph hp vi vi gi tr hostControlIndex ca mt hoc nhiu dng trong bng host. + hostTimeInPkts. S gi tin truyn ti host c chp nhn, k t khi n c qun l bi bng host. + hostTimeOutPkts. S gi tin, k c gi tin hng, m host ny truyn ra k t khi c qun l bi bng host. + hostTimeInOctets. S octet truyn ti a ch host ny, k t khi c bng host qun l. + hostTimeOutOctets. S octet m host ny truyn ra tnh t khi n c qun l trong bng host. + hostTimeOutErrors. S gi tin ca host ny truyn ra b hng, tnh t khi host c qun l bi bng host. + hostTimeOutBroadCastPkts. S gi tin mang a ch broadcast m host ny truyn ra c chp nhn, k t khi n c qun l bi bng host. + hostTimeMultiCastPkts. S gi tin mang a ch multicast m ht ny truyn ra v c chp nhn, k t khi n c qun l bi bng host.

II. 5 Nhm HostTopN: Nhm hostTopN c dng khi chuNn b cc bo co thng k m t v N host u tin theo trnh t ch ra bi trm qun l. Bo co l mt tp hp cc thng tin thng k v mt nhm i tng mt host c theo di t mt giao tip no . Cc thng tin ny c thu thp trong mt khong thi gian nht nh.Nguyn Nam Hng B mn K thut my tnh v Mng i hc Thy li Trang 11/23


Nhm ny rt trch cc thng tin bo co da theo nhm host. Nhm hostTopN gm 2 bng: bng iu khin v bng d liu. Bng iu khin: mi dng trnh by mt bo co v mt host thuc top-N chuNn b, vi cc tham s sau: + hostTopNControlIndex. Ch s phn bit dng trong bng. + hostTopNHostIndex. Ch s lin kt vi bng host. + hostTopNRateBase. Ch ra mt trong 7 bin ca bng host c dng lm tham s thng k cho bo co hostTopNRate. + hostTopNTimeRemaining. S giy cn li ca thi gian ly mu khi bo co ny c chuNn b. + hostTopNDuration. Khong thi gian ly mu, tnh bng giy, thc hin bo co hostTopN ny. + hostTopNRequestedSize. S host ti a yu cu bo co. + hostTopNGrantedSize. S host ti a c trong bng top-N. + hostTopNStartTime. Gi tr sysUpTime khi bo co top-N c kch hot. + hostTopNOwner. Thc th c trch nhim cu hnh bng ny. + hostTopNStatus. Trng thi dng.

Bng d liu: hostTopNTable, mi dng m t mt trong s N host, c cc tham s sau: + hostTopNReport. S nguyn ch ra host no trong s top-N host lin quan ti bo co. + hostTopNIndex. Ch s phn bit dng trong bng Top-N. + hostTopNAddress. a ch vt l ca host. + hostTopNRate. Gi tr sai lch ca bin chn trong cng thi gian ly mu. Bin chn ny c ch ra bi tham s hostTopNRateBase trong barnng iu khin hostTopN.


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II. 6 Nhm Matrix: Nhm ny lu tr thng tin giao vn gia mt cp host m RMON probe theo di. Cc i tng ca nhm ny gip nh qun l tm ra nhng cp host no dng server mng nhiu nht, hay trao i vi nhau nhiu nht. Bao gm ba bng: bng iu khin ma trn v hai bng d liu m mt lu tr thng tin giao vn t ngun n ch (matrixSDTable), bng kia lu tr chiu ngc li (matrixDSTable). Bng iu khin ma trn: Mi dng c to ra qun l mt giao tip, cng c ngha n tng ng vi mt mng con, mang cc tham s sau: + matrixControlIndex. Ch s nhn din dng trong bng. + matrixControlDataSource. Nhn din giao tip ngun d liu. + matrixControlTableSize. S dng trong bng matrixSDTable ca giao tip ny. Con s ny phi ph hp vi s dng trong bng matrixDSTable. + matrixControlLastDeleteTime. Gi tr systUpTime khi dng cui cng b xa khi bng matrixSDTable hay matrixDSTable. + matrixControlOwner. Thc th mang trch nhim cu hnh bng ny. + matrixControlStatus. Trng thi dng Bng matrixSDTable: ghi chp d liu v giao vn gi i t host ngun, mi host chim mt dng, vi cc tham s sau: + matrixSDSourceAddress. a ch vt l ca host ngun. +matrixSDDestAddress. a ch vt l ca host ch. +matrixSDSDIndex. Gi tr ch s lin kt vi dng trong bng ma trn. Cc cp trong cng giao tip s c chung gi tr ny. +matrixSDPkts. S gi tin truyn t a ch ngun ti a ch ch. +matrixSDOctets. S octet truyn t a ch ngun ti a ch ch. +matrixSDErrors. S gi tin truyn t a ch ngun ti a ch ch b hng.


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Bng matrixDSTable, l mt nh x ton nh ca bng kia nhng hng sp xp cc bn ghi c chiu ngc li.

II.7 Nhm Filter Nhm ny cung cp c ch ch th cho mt trm qun l i vi mt RMON probe quan trc cc giao vn trong mt giao tip mt cch c la chn bng mt biu thc lc. C hai kiu lc: theo d liu v theo trng thi. Kiu lc theo d liu: cho php mt RMON probe hin th d liu thu thp bng cch so snh mu bit quan st c vi mu lc. Kiu lc theo trng thi: cho php mt RMON probe hin th cc gi tin thu thp theo trng thi ca chng (valid, invalid, m li, v.v). Hai kiu lc ny cn c th t hp vi cc ton t logic AND v OR, to nn nhng biu thc logic phc tp hn. Nhm ny bao gm hai bng: bng lc v bng knh truyn. Bng lc: Mi dng ca bng lc gm c b lc d liu v lc trng thi: + filterIndex. Ch s nhn din dng. +filterChannelIndex. Ch s knh truyn m b lc p dng. +filterPktDataOffset. a ch offset ch ra im bt u p dng d liu lc vi chui bit ph hp. +filterPktData. D liu ca b lc d liu m n cn ph hp vi cc gi tin u vo. +filterPktDataMask. Mt n so snh +filterPktDataNotMask. Mt n o p dng trong so snh. +filterPktDataStatus. Trng thi ca b lc trng thi so snh vi gi tin u vo. +filterPktDataStatusMask. Mt n p dng trong so snh trng thi. +filterPktDataStatusNotMask. Mt n o p dng trong so snh trng thi. +filterOwner. Thc th c nhim v cu hnh bng.Nguyn Nam Hng B mn K thut my tnh v Mng i hc Thy li Trang 14/23


+filterStatus. Trng thi ca bng. Bng knh truyn: Mi knh truyn c nh ngha bng mt dng ca bng knh truyn. Ngoi ra cn c nhiu b lc kt hp vi n. +channelIndex. Ch s phn bit dng trong bng. +channelIfIndex. Ch s nhn dng giao tip, tc nhn din mng con m cc b lc c p dng. +channelAcceptType. i tng ny kim sot cc hnh ng lc trn knh. Nu n mang gi tr acceptMatched (1), th cc gi tin s ch c chp nhn cho vo knh nu c d liu v trng thi ph hp vi t nht mt b lc. Nu c gi tr acceptFailed (2), cc gi tin ch c chp nhn cho vo knh khi n khng ph hp vi bt k trng thi no. +channelDataControl. i tng ny kim sot lung d liu i qua knh. Nu bng 1 (on), n cho php d liu, trng thi v cc s kin i qua. Ngc li, nu bng 2 (off), n cn knh. +channelTurnOnEventIndex. Ch ra s kin c cu hnh kch hot i tng channelDataControl (off i tng channelDataControl (on on) khi s kin sinh ra. +channelTurnOffEventIndex. Ch ra s kin c cu hnh v hiu off) khi s kin sinh ra. +channelEventIndex. Ch ra mt s kin s c sinh ra khi i tng channelDataControl c kch hot v c mt gi tin ph hp. (Hot ng ging nh eventIndex ca nhm s kin. +channelEventStatus. Trng thi s kin ca knh, mang mt trong cc gi tr sau: - eventReady (1). Pht sinh mt s kin. - eventFired (2). Probe thit lp i tng channelEventStatus mang gi tr ny khi mt s kin c sinh ra. Khi n mang gi tr ny, khng s kin no khc c sinh ra na. - eventAlwaysReady (3). Cho php sinh cc s kin khng hn ch.


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+ channelMatches. S ln so snh gi tin chnh xc ca knh. i tng ny cp nht s kin thay cho channelDataControl khi n off. +channelDescription. Chui vn bn m t c tnh ca knh. +channelOwner. Thc th c nhim v cu hnh knh. +channelStatus. Trng thi hot ng ca dng. II.8 Nhm Packet Capture Buffer: Nhm i tng ny dng chn bt cc gi tin theo tiu chuNn lc. N gm hai bng: Bng iu khin b m v bng gi m. Mi b m c to ra trong mt dng ca bng iu khin b m. Bng iu khin b m: Quy nh k thut gm kch thc b m, hnh ng thi hnh khi b m y v mt s hnh ng khc na. + bufferControlIndex. Ch s phn bit dng trong bng. +bufferControlChannelIndex. Ch s lin kt vi knh ngun ca cc gi tin. Ch s ny phi bng gi tr ca i tng channelIndex trong bng knh truyn. +bufferControlFullStatus. i tng ny biu th b m cn khong trng chp nhn cc gi tin khc hay khng. Hai gi tr c th nhn l: - spaceAvailable (1). Chp nhn thm. - full (2). Chp nhn thm nu i tng bufferControlFullAction mang gi tr wrapWhenFull, khi n xa bt cc gi tin c (FIFO). B m thc s ngng nhn gi tin nu i tng

bufferControlFullAction mang gi tr lockWhenFull. + bufferControlFullAction. iu khin hot ng khi b m y. Hai gi tr ni trn l: lockWhenFull (1) v wrapWhenFull (2). + bufferControlCaptureSliceSize. S octet ti a ca tng gi tin lu trong b m. + bufferControlDownloadSliceSize. S octet ti a ca tng gi tin trong b m ri c a vo thng ip SNMP.


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+bufferControlDownloadOffset. a ch offset ca octet u tin trong tng gi tin lu trong b m ri n c trch t a vo thng ip SNMP. +bufferControlMaxOctetsRequested. S octet ti a cn lu trong b m, gm c tiu . +bufferControlMaxOctetsGranted. S octet ti a thc s c th lu trong b m, gm c tiu . Nu gi tr ny = 1, b m c php lu ht kh nng. +bufferControlCapturedPackets. S gi tin hin c trong b m. +bufferControlTurnOnTime. Gi tr systUpTime (nhm h thng) khi b lu m c kch hot. +bufferControlOwner. Thc th c nhim v cu hnh bng. +bufferControlStatus. Tnh trng ca bng. Bng lu m: lu tr mi dng mt gi tin, v mi dng ny c ch s ha tng ng vi bng iu khin bit gi tin ny ly t knh no. +captureBufferIndex. Ch s bufferControlEntry lin kt bi bng iu khin b m. +captureBufferIndex. Ch s phn bit dng. +captureBufferPacketID. Ch s phn bit th t bt gi gi tin, theo giao tip. +captureBufferPacketData. D liu trong gi tin cho n a ch offset (trong bufferControlDownloadOffset). +captureBufferPacketLength. Chiu di gi tin thc s lu trong bng m. +captureBufferPacketTime. Thi gian (mili giy) t khi b m c kch hot. +captureBufferPacketStatus. Trng thi li ca gi tin b bt gi: 0. Gi tin di hn 1518 octet. 1. Gi tin ngn hn 64 octet. 2. Li CRC hoc li khc.Nguyn Nam Hng B mn K thut my tnh v Mng i hc Thy li Trang 17/23


3. Gi tin u tin ca mt tp gi tin x l khng chnh xc. 4. Trnh t gi tin trong b m sai khc.

II.9 Nhm Event Nhm ny dng xc nh cc s kin pht sinh t thit b. Mt s kin c th c kch hot bi mt iu kin tiu chuNn c nh ngha trc. Mt s kin loi ny thng dn n vic agent sinh ra mt thng ip TRAP gi manager. Nhm ny gm hai bng: bng iu khin s kin v bng log.

Bng iu khin s kin: eventTable, gm cc tham s lm pht sinh s kin. Mi dng biu din mt s kin, gm cc i tng sau: +eventIndex.Ch s s kin. +eventDescription. Chui vn bn m t s kin. +eventType. Cch khai bo ca RMON probe i vi s kin: -none (1). Khng khai bo. -log (2). Khai bo bng cch to mt dng trong bng log. -snmp-trap (3). Gi thng ip SNMP Trap ti cc trm qun l. -log-and-trap (4). C log v Trap. +eventCommunity. Chui an ninh SNMP community ca thc th m thng ip Trap c gi n. +eventLastTimeSent. Gi tr sysUpTime ti thi im sinh ra s kin. +eventOwner. Thc th c trch nhim cu hnh bng. +eventStatus. Tnh trng ca bng. Nu gi tr khng phi l valid (1), th tt c cc mc log lin quan s b xa.

Bng logTable, ghi chp mi dng mt s kin. Mi dng gm: +logEventIndex. Ch s lin kt vi bng s kin. +logIndex. Ch s phn bit vi cc dng c cng kiu s kin trong bng.Nguyn Nam Hng B mn K thut my tnh v Mng i hc Thy li Trang 18/23


+logTime. Gi tr sysUpTime khi to dng ghi chp. +logDescription. M t s kin

III. Gii thiu RMON2Qu trnh pht trin RMON MIB c bt u t nm 1994, thng qua RFC 2021, thng 1/1997, v tr thnh RMON2trong khi phin bn gc gi l RMON1. RMON2 m rng phm vi theo di t tng vt l cho ti tn tng ng dng, bao gm hai kha cnh. Cc tnh nng theo di giao vn t tng mng cho php mt probe vt c ra ngoi phn on ca n v thy c cc giao vn i n n qua cc router. iu ny m ra ton b kh nng qun l i vi mt RMON probe: 1. Khi c mt lung giao vn qu ti, probe bit c lung ny n t router no, host no. 2. Khi mt router qu ti bi lung thng tin gi ra, proble bit host no trong phn on ca n lm qu ti router, bit lung thng tin gi n mng no. 3. Khi c mt lng thng tin ln qua LAN (c vo v ra), probe c th bit nhng mng no, host no c trch nhim vi chng.

Kh nng theo di giao vn t cc tng cao hn tng mng (cao hn tng IP) cho php probe m hnh ha c giao vn mng ca tng giao thc v tng ng dng, t qun l giao vn mng tt hn.

RMON2 MIB kh di dng v phc tp, cng bao gm 9 nhm. + Nhm th mc giao thc (Protocol Directory Group), cho php probe theo di, qun l cc giao thc bng cc hnh ng nh thm, xa, cu hnh li tng dng ca bng.


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+ Nhm giao thc phn phi (protocol distribution group) cho php probe theo di cc d liu thng k giao vn thng qua mt giao thc h tr mng con. Ngoi ra, n cng theo di s octet c truyn ti cc host thng qua tng giao tip c th. + Nhm nh x a ch (Address Map Group), duy tr mt tp quan h nh x gia a ch tng vt l (MAC) v a ch mng. Vic ny cho php probe pht hin ra cc host mi, t theo di c ng i cho cc giao vn pht sinh t cc host ny. + Nhm tng mng ca host (Network Layer Host Group), nhm i tng ny cho php ngi dng gii m cc gi tin n (da theo a ch mng). Cho php nh qun l mng quan st vt c ra ngoi mt router cng nh ti tn cc host ni vi router . + Nhm tng ng dng ca host (Application Layer Host Group), theo di cc giao thc thuc tng ng dng, bit lng giao vn v ch n ca tng giao thc ny. + Cc nhm ma trn tng mng (Network Layer Matrix Groups), cc i tng ny cho php probe theo di giao vn gia tng cp a ch mng trong phm vi qun l ca n. Cc tham s theo di thuc v hai loi v qun l trong hai bng: d liu ngun v d liu ch. Probe cn theo di giao vn ca N cp u tin (top N), sinh cc bo co gi ti cc trm qun l. + Nhm Ma trn tng ng dng (Application Layer Matrix Group), cho php probe theo di qua giao thc v cc giao vn truyn gi gia tng cp a ch mng m probe khm ph ra. Probe cn duy tr cc thng k tng ng dng trong top-N. + Nhm thu thp lch s ngi dng (User History Collection Group), nh k truy vn i tng MIB ly cc tham s ngi dng. + Nhm cu hnh probe (Probe Configuration Group), nhm ny kim sot cu hnh qua cc tham s iu hnh ca probe theo mt tp tham s chuNn m n c p dng bi tt c cc nh sn xut v phn phi probe.Nguyn Nam Hng B mn K thut my tnh v Mng i hc Thy li Trang 20/23


III. V d ng dng RMON Lm th no mt RMON probe c s dng theo di t xa cc tiu chuNn giao vn trong mt LAN?

(back)

Bi ton: nh qun l quan tm ti hai host (N-host, N =2). Hai host ny, nm y hnh v trn, truyn nhiu gi tin b hng nht trong mt khong thi gian no . Cc bc tin hnh ca mt RMON c m t ( mc tng qut nht) nh sau: 1. Nh qun l gi SetRequest PDU cho agent, to ra mt dng mi trong bng iu khin host, cc tham s request gm: - hostControlIndex = 1. - hostControlDataSource = ch s s ca giao tip mng gn lin vi probe. - hostControlTableSize = 5, s host ca LAN. - hostControlOwner = ID ca trm qun l.


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Ngoi ra cn mt s thng ip khc c trao i gia nh qun l v agent (lin quan ti vic to dng). 2. Trm qun l gi SetRequest PDU cho agent to dng mi trong bng iu khin hostTopN vi cc tham s sau: - hostTopNControlIndex = 10 (ch s nhn din dng). - hostTopNHostIndex = 1 (l gi tr ca hostControlIndex). - hostTopNRateBase = hostOutErrors (bin cn to bo co). - hostTopNDuration = khong thi gian ly mu. - hostTopNRequestedSize = 2 (s host ti a trong bng top-N cn bo co). - hostTopNGrantedSize = 2 (s host ti a c agent cho php truy xut bng top-N). Sau khi dng ny c to thnh cng (cn thm mt s thng ip to dng na) th trm qun l khng quan tm na, ch p ng t agent cho n ht thi gian ly mu. 3. Agent lin tc thu thp d liu giao vn trn tng host v to cc dng mi trong bng host theo phng thc round-robin (xa c, thm mi). Cc tham s d liu gm: - hostInPkts. S gi tin m host nhn. - hostOutPkts. S gi tin m host truyn - hostOutErrors. S gi tin host truyn gp li. 4. Vo cui thi gian ly mu, agent to bo co theo ch nh ca bng iu khin top-N : bin cn theo di (hostOutErrors), s host c bo co (2) v cc ch dn khc na. 5. Trm qun l gi GetBulkRequest PDU ly d liu ca ton b bng. ng dng ny c mc ch minh ha cch thc s dng cng nhng mc tiu quan trng ca RMON. N cho thy cch thc m mt probe trt b gnh nng truy vn cc thit b mng lin tc. Khi to c hai dng mi trong bngNguyn Nam Hng B mn K thut my tnh v Mng i hc Thy li Trang 22/23


iu khin th manager khng cn phi lu tm cho ti khi ly c kt qu. Tip na, probe rt trch ti a cc thng tin m manager quan tm. Cng v d ny cho thy rng manager s nhn c bo co theo ng nhng g mnh mun.

TM TTBi ny, kt hp vi bi 4, cung cp cch nhn tng th i vi vic qun l cc mng kt ni vi Internet: SNMPv2 v RMON. SNMPv2 nhm vo SMI, MIB, cng cc hot ng ca giao thc. Trong khi qun l mng t xa vi RMON1 v RMON2 khai thc giao thc SNMP t xa. Tc l m rng cc chuNn SNMP m khng i hi phi thay i cc chuNn ny hay pht trin thm cc chuNn khc. Xt v bn cht, RMON l mt MIB vi chc nng c bit, va cho php qun l, va rt trch cc bo co nhanh nht, chnh xc nht c th m khng phi tng tc trc tip vi OSF hay MF bng cc giao tip Q. u im na ca RMON l cho php pht trin cc phn mm qun l mng tng thch vi TMN v s dng giao thc SNMP.

CU HI1. M t cu trc h thng RMON? 2. and an RMON probe l g? 3. RMON MIB tun th SNMP i vi RowStatus ra sao? 4. Tm tt cc chc nng ca mt RMON probe thng qua cc nhm i tng ca n? 5. Nu nhng kha cnh chc nng quan trng m RMON2 m rng t RMON1?


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