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Cc mng khng dy v di ng 1
Chng 6Cc mng khng dy v di ng
Computer Networking: A Top Down Approach Featuring the Internet, 3rd edition. Jim Kurose, Keith RossAddison-Wesley, July 2004.
All material copyright 1992006J.F Kurose and K.W. Ross, All Rights Reserved
Slide ny c bin dch sang ting Vit theo s cho php ca cc tc gi
Cc mng khng dy v di ng 2
Chng 6: Ni dung trnh by
6.1 Gii thiu Wireless
6.2 Cc kt ni, c tnh
CDMA
6.3 IEEE 802.11 wireless LANs (wi-fi)
6.4 Truy cp Cellular Internet kin trc
cc chun (v d: GSM)
Tnh di ng
6.5 Cc nguyn l: nh a ch v routing n cc ngi dng di ng
6.6 Mobile IP
6.7 Qun l s di ng trong cc mng cellular
6.8 Tnh di ng v cc giao thc lp cao hn
6.1 Gii thiu Wireless
Cc mng khng dy v di ng 3
Cc mng khng dy v di ng 4
Gii thiu
Background:
s lng thu bao in thoi di ng (khng dy) ln hn c dy
mng: my tnh xch tay, palm, PDA, in thoi Internet s truy cp Internet bt k thi im no
2 thch thc quan trng (khc nhau) truyn thng trn cc kt ni khng dy (wireless)
qun l ngi dng di ng, l ngi s thay i v tr kt ni vi mng
6.2 Cc kt ni, c tnh
Cc mng khng dy v di ng 5
Cc mng khng dy v di ng 6
Cc thnh phn ca 1 mng di ng
h tng mng
wireless hosts
laptop, PDA, IP phone
chy cc ng dng
c th c nh hoc di ng wireless khng c
ngha lun phi di ng
Cc mng khng dy v di ng 7
Cc thnh phn ca 1 mng di ng
trm c s
c trng bi kt ni vo mng c dy (wired)
relay - p ng vic chuyn cc gi gia mng c dy v host khng dy trong vng
v d: cc access point 802.11
h tng mng
Cc mng khng dy v di ng 8
Cc thnh phn ca 1 mng di ng
kt ni wireless
c trng bi dng kt ni khng dy n trm c s
cng dng nh kt ni backbone
giao thc a truy cp
cc tc truyn dliu, khong cch truyn khc nhau
h tng mng
Cc mng khng dy v di ng 9
Cc c tnh ca cc chun kt ni khng dy
384 Kbps
56 Kbps
54 Mbps
5-11 Mbps
1 Mbps802.15
802.11b
802.11{a,g}
IS-95 CDMA, GSM
UMTS/WCDMA, CDMA2000
.11 p-to-p link
2G
3G
trongnh
10 30m
bn ngoi
50 200m
vngtrung bnh
200m 4Km
vng khongcch xa
5Km 20Km
Cc mng khng dy v di ng 10
Cc thnh phn ca 1 mng di ng
kiu c s h tng mng
trm c s kt ni khng dy vi mng c dy
handoff: linh hot thay i trm c s cung cp kt ni n mng c dy
h tng mng
Cc mng khng dy v di ng 11
Cc thnh phn ca 1 mng di ng
ch ad-hoc
khng c cc trm cs
cc nt ch c th lin lc vi nhau trong vng kt ni
cc nt t t chc vo trong 1 mng: route gia chng
Cc mng khng dy v di ng 12
cc c tnh ca kt ni khng dy
Khc bit vi c ni dy .
cng tn hiu gim: tn hiu radio gim khi lan truyn trn ng (mt mt trn ng truyn)
nhiu bi cc ngun khc: tn s mng khng dy chun ha (vd: 2.4GHz) c nhiu thit bdng, cc thit b gy nhiu ln nhau
lan truyn nhiu hng
. lm cho truyn thng qua kt ni khng dy thm nhiu kh khn (thm ch c trong trng hp im-im)
Cc mng khng dy v di ng 13
cc c tnh ca kt ni khng dynhiu ngi gi v nhiu ngi nhn khng dy to ra
thm cc vn (hn c trng hp a truy cp):
AB
C
vn tim n u cui B, A nghe thy nhau
B, C nghe thy nhau
A, C khng nghe thy nhau
ngha l A, C khng bit v s can thip ca B
A B C
cng tn hiu ca A
space
cng tn hiu ca C
gim mc tn hiu: B, A nghe thy nhau
B, C nghe thy nhau
A, C khng nghe thy nhau d giao thoa ti B
Cc mng khng dy v di ng 14
Code Division Multiple Access (CDMA)
dng trong mt s chun knh pht khng dy (cellular, v tinh)
m duy nht gn cho mi user, ngha l phn hoch tp m
tt c user chia s cng tn s, nhng mi user c tin trnh (m) ring m ha d liu
tn hiu m ha = (tn hiu gc) X (tin trnh ring)
gii m: tch trong ca tn hiu m ha v tin trnh ring
cho php nhiu user cng tn ti v truyn ng thi vi nhiu ti thiu (nu cc m l trc giao)
Cc mng khng dy v di ng 15
CDMA m ha/gii m
slot 1 slot 0
d1 = -1
1 1 1 1
1- 1- 1- 1-
Zi,m= di.cm
d0 = 1
1 1 1 1
1- 1- 1- 1-
1 1 1 1
1- 1- 1- 1-
1 1 11
1-1- 1- 1-
slot 0channeloutput
slot 1channeloutput
channel output Zi,m
bn gi
code
databits
slot 1 slot 0
d1 = -1
d0 = 1
1 1 1 1
1- 1- 1- 1-
1 1 1 1
1- 1- 1- 1-
1 1 1 1
1- 1- 1- 1-
1 1 11
1-1- 1- 1-
slot 0channeloutput
slot 1channeloutputbn nhn
code
receivedinput
Di = SZi,m.cmm=1
M
M
Cc mng khng dy v di ng 16
CDMA: nhiu do 2 bn gi
6.3 Cc LAN khng dy - IEEE 802.11 (wi-fi)
Cc mng khng dy v di ng 17
Cc mng khng dy v di ng 18
IEEE 802.11 Wireless LAN
802.11b ph sng radio khng c
licence, vng t 2.4-5 GHz
tc ln n 11 Mbps
ph lan truyn trc tip trong lp physical
tt c cc host dng cng m
ph bin rng ri, dng cc trm c s
802.11a vng t 5-6 GHz
tc ln n 54 Mbps
802.11g vng t 2.4-5 GHz
tc ln n 54 Mbps
tt c u dng CSMA/CA cho c cha truy cp
tt c u c trm cs v cc phin bn mng ad-hoc
Cc mng khng dy v di ng 19
Kin trc 802.11 LAN
host khng dy truyn thng vi trm c s
trm c s = access point (AP)
Basic Service Set (BSS)(gi l cell) cha:
cc host khng dy
access point (AP
ch ad hoc: ch c cc host
BSS 1
BSS 2
Internet
hub, switchhoc router
AP
AP
Cc mng khng dy v di ng 20
802.11: cc knh, s lin kt
802.11b: ph t 2.4GHz-2.485GHz c chia thnh 11 knh vi tn s khc nhau
qun tr AP chn tn s cho AP
nhiu c th: knh c th ging vi AP bn cnh!
host: phi lin kt vi 1 AP qut cc knh, lng nghe cc frame bo hiu
cha tn ca AP (SSID) v cc a ch MAC
chn AP lin kt
c th phi thc hin vic chng thc (xem chng 8)
thng s chy DHCP ly a ch IP trong subnet
Cc mng khng dy v di ng 21
IEEE 802.11: a truy cp
trnh tranh chp: cc nt truyn cng thi im
802.11: CSMA cm nhn trc khi truyn khng xung t vi qu trnh ang truyn ca nt khc
802.11: khng pht hin tranh chp! kh khn cm nhn tranh chp khi truyn v cc tn hiu
nhn b yu
khng th cm nhn tt c cc tranh chp trong mi trng hp: cc u cui che khut, tn hiu yu
mc tiu: trnh cc tranh chp: CSMA/C(ollision)A(voidance)
AB
CA B C
cng tn hiu ca A
space
cng tn hiu ca C
Cc mng khng dy v di ng 22
Giao thc IEEE 802.11 MAC: CSMA/CA
Bn gi 802.11
1 Nu cm nhn knh rnh th truyn ton bframe (khng pht hin tranh chp)
2 Nu knh bn th:
khi to thi gian ch i ngu nhin
b nh th gim xung trong khi knh rnh
truyn khi b nh th kt thc
nu khng c ACK, tng thi gian ch i ngu nhin, lp li bc 2
Bn nhn 802.11
- Nu frame nhn tt (OK)tr li tn hiu ACK
Bn gi Bn nhn
DIFS
data
SIFS
ACK
Cc mng khng dy v di ng 23
Trnh cc tranh chp (tt)
tng: cho php bn gi c ng k trc knh hn l truy cp ngu nhin cc frame d liu: trnh tranh chp ca vi cc frame di
u tin bn gi gi cc gi request-to-send (RTS) nh n trm c s dng CSMA
cc RTS c th vn xung t vi cc ci khc (nhng t)
trm c s broadcasts tn hiu clear-to-send (CTS) tr li cho RTS
RTS c tt c cc nt lng nghe
bn gi truyn frame d liu
cc trm khc tr hon vic truyn
Trnh tranh chp trit dng cc gi ng k trc nh!
Cc mng khng dy v di ng 24
Trnh tranh chp: trao i RTS-CTS
APA B
time
DATA (A)
tranh chp ng k trc
tr hon
Cc mng khng dy v di ng 25
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
802.11 frame: nh a ch
a ch 2: a ch MAC ca host hoc AP truyn frame ny
a ch 1: a chMAC ca host hoc AP nhn frame ny
a ch 3: a ch MAC ca router m AP gn vo
a ch 4: ch dng trong ch ad-hoc
Cc mng khng dy v di ng 26
Internetrouter
AP
H1 R1
AP MAC addr H1 MAC addr R1 MAC addr
address 1 address 2 address 3
802.11 frame
R1 MAC addr AP MAC addr
dest. address source address
802.3 frame
802.11 frame: nh a ch
Cc mng khng dy v di ng 27
framecontrol
durationaddress
1address
2address
4address
3payload CRC
2 2 6 6 6 2 6 0 - 2312 4
seqcontrol
TypeFromAP
SubtypeToAP
More frag
WEPMoredata
Powermgt
Retry RsvdProtocolversion
2 2 4 1 1 1 1 1 11 1
802.11 frame: nh a chkhong thi gian truyn ng k (RTS/CTS)
s tin trnh frame(dnh cho ARQ tin cy)
kiu frame(RTS, CTS, ACK, d liu)
Cc mng khng dy v di ng 28
hub hocswitch
AP 2
AP 1
H1 BBS 2
BBS 1
802.11: tnh di ng trong cng subnet
router H1 duy tr trong cng
IP subnet: a ch IP cng lm ging vy
switch: AP no lin kt vi H1? t hc (Ch. 5): switch
s nhn thy frame tH1 v nh port no dng chm n H1
Cc mng khng dy v di ng 29
Mbn knhbao trm
S
SS
P
P
P
P
M
S
thit b master
thit b slaver
thit b nh v (khng hot ng)P
802.15: mng vng c nhn
ng knh < 10 m
thay th cho cc loi cp (mouse, keyboard, headphones)
ad hoc: khng thit b cnh
master/slaver: cc slaver yu cu quyn gi
(n master)
master chp nhn cc yu cu
802.15: pht trin tBluetooth di tn s radio t 2.4-2.5
GHz
tc ln n 721 kbps
6.4 Truy cp Cellular Internet
Cc mng khng dy v di ng 30
Cc mng khng dy v di ng 31
Mobile Switching
Center
mng in thoi cng cng &Internet
Mobile Switching
Center
Cc thnh phn ca kin trc mng cellular
kt ni cc cell trong mt vng rng ln qun l cc cuc gi iu khin
MSC
bao trm mt vng trm c s ging vi 802.11 AP nhng user gn vo mng thng qua trm c s air-interface: giao thc lp physical v link gia thit b di ng & trm c s
cell
mng ni dy
Cc mng khng dy v di ng 32
cc mng Cellular: hop u tin
2 k thut chia s ph sng radio t di ng n trm c s
FDMA/TDMA kt hp: chia ph thnh cc knh tn s, mi knh c chia thnh cc time slot
CDMA: code division multiple access
cc di tn s
cc slot thi gian
Cc mng khng dy v di ng 33
cc chun Cellular: tng quan
cc h thng 2G: cc knh ting
IS-136 TDMA: FDMA/TDMA kt hp (Bc M)
GSM (global system for mobile communications): FDMA/TDMA kt hp rt ph bin
IS-95 CDMA: code division multiple access
GSM
Cc mng khng dy v di ng 34
cc chun Cellular: tng quan
cc h thng 2.5 G: cc knh ting & d liu vi nhng ngi khng th ch i dch v 3G: 2G m
rng
general packet radio service (GPRS) pht trin t GSM
d liu c gi trn nhiu knh
enhanced data rates for global evolution (EDGE) cng pht trin t GSM, dng iu ch tng cng
ngy nay, tc c nng ln n 384K
CDMA-2000 (giai on 1) ngy nay, tc c nng ln n 144K
pht trin t IS-95
Cc mng khng dy v di ng 35
cc chun Cellular: tng quan
cc h thng 3G: knh ting / d liu
Universal Mobile Telecommunications Service (UMTS)
th h GSM k tip, nhng dng CDMA
CDMA-2000
.. cn nhiu ti th v hn v mng di ng
6.5 Cc nguyn l: nh a ch v routing n cc ngi
dng di ng
Cc mng khng dy v di ng 36
Cc mng khng dy v di ng 37
Di ng l g?
s phn b theo tnh cht ca mng di ng:
khng di ng tnh di ng cao
user khng dy di ng, dng cng AP
user di ng, truyn thng qua nhiu AP trong khi vn ginguyn cc kt ni (dng in thoi cell)
user di ng, kt ni/hy kt ni tmng dng DHCP.
Cc mng khng dy v di ng 38
Di ng l g?
mng gia nh: gia nh bn vng ca cc thit bdi ng(vd: 128.119.40.186/24)
a ch c nh: a chtrong mng gia nh, c th lun lun dng chm n mng di ngvd: 128.119.40.186
home agent: thc th s hon tt cc chc nng di ng
WAN
correspondent
Cc mng khng dy v di ng 39
Di ng l g?
Care-of-address: a chtrong visited network.(vd: 79.129.13.2)
WAN
visited network: l mng trong thit b di ng ang thng tr (vd: 79.129.13/24)
a ch c nh: gi nguyn, khng i (vd: 128.119.40.186)
foreign agent: l thc th trong visited network thc hin nhng chc nng di ngcorrespondent: c
nhu cu truyn thng vi mng di ng
Cc mng khng dy v di ng 40
Lm th no lin lc vi thit b di ng khc?
tm trong tt c danh b in thoi?
gi cho cha m ca bn y?
ch i bn y s cho bn bit l ang u?
Ti mun bit Alice ang u?
Kho st trng hp 1 ngi bn thng xuyn thay i a ch, lm sao tm?
Cc mng khng dy v di ng 41
Cc cch tip cn
cho routing qun l: Thng bo a ch c nh ca thit b di ng bng cch trao i bng routing
bng routing ny s ch cho bit thit b di ng ang u
khng thay i g h thng u cui
cho h thng u cui qun l: routing khng trc tip: truyn thng t
correspondent n thit b di ng thng qua home agent, sau chuyn n thit b xa
routing trc tip: correspondent ly a ch ngoi ca thit b di ng, gi trc tip n thit b di ng
Cc mng khng dy v di ng 42
Cc cch tip cn
cho routing qun l: Thng bo a ch c nh ca thit b di ng bng cch trao i bng routing
bng routing ny s ch cho bit thit b di ng ang u
khng thay i g h thng u cui
cho h thng u cui qun l: routing gin tip: truyn thng t correspondent
n thit b di ng thng qua home agent, sau chuyn n thit b xa
routing trc tip: correspondent ly a ch ngoi ca thit b di ng, gi trc tip n thit b di ng
khng linh hot vi hng triu
thit b di ng
Cc mng khng dy v di ng 43
ng nhp
Kt qu cui cng:
Foreign agent bit v thit b di ng
Home agent bit v tr ca thit b di ng
WAN
home networkvisited network
1
thit b di ng tip xc vi foreign agent ng nhp vo visited network
2
foreign agent tip xc vi agent home: thit b di ng ny thng tr trong mng ca ti
Cc mng khng dy v di ng 44
Tnh di ng thng qua Routing gin tip
wide area network
homenetwork
visitednetwork
3
2
41
correspondent nh vcc gi dng a chhome ca thit b di ng
home agent chn cc gi, chuyn tip n foreign agent
foreign agent nhn cc gi, chuyn tip n thit b di ng
thit b di ng phn hi trc tip cho correspondent
Cc mng khng dy v di ng 45
Routing gin tip: ch thch
Thit b di ng dng 2 a ch:
a ch c nh: dng bi correspondent (v tr ca thit b trong sut i vi correspondent)
care-of-address: dng bi home agent chuyn tip cc datagrams n thit b di ng
chnh cc thit b di ng c th hon thnh cc chc nng ca foreign agent
routing tam gic: correspondent-home-network-thit b di ng
khng hiu qu khi
correspondent, thit b
di ng nm cng mng
Cc mng khng dy v di ng 46
Routing gin tip: di chuyn gia cc mng
gi s user di ng di chuyn n mng khc ng k vi foreign agent mi
foreign agent mi ng k vi home agent
home agent cp nht care-of-address cho thit bdi ng
cc gi tip tc c chuyn tip n thit b di ng (nhng vi care-of-address mi)
vic thay i mng l trong sut: cc kt ni vn c duy tr!
Cc mng khng dy v di ng 47
Di ng thng qua Routing trc tip
WAN
homenetwork
visitednetwork
4
2
41correspondent yu cu, nhn foreign address ca thit bdi ng
correspondent chuyn tip n foreign agent
foreign agent nhn cc gi, chuyn tip n thit b di ng
thit b di ng phn hi trc tip vi correspondent
3
Cc mng khng dy v di ng 48
Routing trc tip: cc ch thch
khc phc vn routing tam gic
khng trong sut i vi correspondent:correspondent phi ly care-of-address thome agent
iu g xy ra nu thit b di ng thay i visited network?
Cc mng khng dy v di ng 49
WAN
1
foreign net visited ngay lc phin lm vic bt uanchor
foreignagent
2
4
foreignagent mi
35
correspondentagent
correspondent
foreignnetwork mi
Accommodating mobility with direct routing
anchor foreign agent (FA): FA trong visited network u tin
d liu lun lun u tin route ti anchor FA
khi thit b di ng di chuyn: FA mi thu xp d liu chuyn tip t FA c (dy chuyn)
6.6 Mobile IP
6.7 Qun l s di ng trong cc mng cellular
6.8 Tnh di ng v cc giao thc lp cao hn
Cc mng khng dy v di ng 50
Cc mng khng dy v di ng 51
Mobile IP
RFC 3220
c nhiu c tnh m chng ta va xem qua:
home agents, foreign agents, ng k foreign-agent, care-of-addresses, ng gi (gi-bn trong-gi)
3 thnh phn cn chun ha:
routing gin tip cc datagrams
pht hin agent
ng k vi home agent
Cc mng khng dy v di ng 52
Mobile IP: routing gin tip
a ch c nh: 128.119.40.186
Care-of address: 79.129.13.2
ch: 128.119.40.186
gi c gi bi correspondent
ch: 79.129.13.2 ch: 128.119.40.186
gi c gi bi home agent n foreign agent: mt gi trong gi
dest: 128.119.40.186
gi foreign-agent-n-thit b
Cc mng khng dy v di ng 53
Mobile IP: pht hin agent
thng bo agent: cc foreign/home agents thng bo dch v bng cch broadcasting cc thng ip ICMP (typefield = 9)
RBHFMGV bits
reserved
type = 16
type = 9 code = 0 = 9
checksum
router address
standard ICMP fields
mobility agent advertisement
extension
length sequence #
registration lifetime
0 or more care-of-addresses
0 8 16 24
R bit: yu cu ng k
H,F bits: home / foreign agent
Cc mng khng dy v di ng 54
Mobile IP: v d ng k
visited network: 79.129.13/24
home agent
HA: 128.119.40.7 foreign agent
COA: 79.129.13.2
COA: 79.129.13.2 .
ICMP agent adv. Mobile agent
MA: 128.119.40.186
registration req.
COA: 79.129.13.2 HA: 128.119.40.7 MA: 128.119.40.186 Lifetime: 9999 identification:714 .
registration req.
COA: 79.129.13.2 HA: 128.119.40.7 MA: 128.119.40.186 Lifetime: 9999 identification: 714 encapsulation format .
registration reply
HA: 128.119.40.7 MA: 128.119.40.186 Lifetime: 4999 Identification: 714 encapsulation format .
registration reply
HA: 128.119.40.7 MA: 128.119.40.186 Lifetime: 4999 Identification: 714 .
time
Cc mng khng dy v di ng 55
Cc thnh phn ca kin trc mng cellular
correspondent
MSC
MSC
MSCMSC
MSC
mng in thoi ni dy cng cng
cc mng cellular khc nhau, iu hnh bi cc nh cung cp khc nhau
Cc mng khng dy v di ng 56
Qun l tnh di ng trong cc mng cellular
home network: mng cc nh cung cp cellular m bn ng k
home location register (HLR): c s d liu trong mng home cha s lng cell phone cnh, thng tin khc (cc dch v, ha n)
visited network: mng trong thit b di ng thng tr
visitor location register (VLR): c s d liu vi cc bn ghi cho mi user hin hnh
c th l home network
Cc mng khng dy v di ng 57
mng in thoi chuyn mch cng cng
mobileuser
homeMobile
Switching Center
HLRhome network
visitednetwork
correspondent
Mobile Switching
Center
VLR
GSM: routing gin tip n thit b di ng
1 cuc gi c route n home network
2
home MSC tra cu HLR,ly s hiu roaming ca thit b di ng trong visited network
3
home MSC thit lp chiu th 2 ca cuc gi n MSC trong visited network
4
MSC trong visited network hon ttcuc gi thng qua trm c s n thit b di ng
Cc mng khng dy v di ng 58
Mobile Switching
Center
VLR
BSS cBSS mi
routingc
routingmi
GSM: handoff vi MSC
mc tiu Handoff: route cuc gi thng qua trm c s mi (khng gin on)
l do handoff:
tn hiu mnh hn n/t BSS mi (kt ni lin tc, t tiu hao nng lng)
cn bng ti: gii phng knh trong BSS hin ti
GSM khng ni ti sao thc hin handoff (chnh sch), chbit cch lm (c ch)
handoff c khi to bi BSS c
Cc mng khng dy v di ng 59
Mobile Switching
Center
VLR
BSS c
1
3
24
5 6
78
GSM: handoff vi MSC
BSS mi
1. BSS c thng bo MSC handoff, cung cp danh sch cc BSS 1+ mi
2. MSC thit lp ng (cp pht ti nguyn) n BSS mi
3. BSS mi cp pht knh radio cho user di ng
4. BSS mi thng bo cho MSC, BSS c: sn sng
5. BSS c ni vi thit b di ng: thc hin handoff vi BSS mi
6. thit b di ng, BSS mi thng bo kch hot knh mi
7. thit b di ng thng bo vi BSS mi n MSC: handoff hon tt. MSC route li cuc gi
8 MSC-c-BSS gii phng ti nguyn
Cc mng khng dy v di ng 60
home network
Home MSC
PSTN
correspondent
MSC
anchor MSC
MSCMSC
(a) trc khi handoff
GSM: handoff gia cc MSC
anchor MSC: MSC u tin trong sut cuc gi cuc gi duy tr route
thng qua anchor MSC
cc MSC mi thm vo cui dy chuyn MSC ging nh thit b di ng di chuyn vo MSC mi
IS-41 cho php ty chn ti thiu ha thu ngn ng i gia cc dy chuyn MSC
Cc mng khng dy v di ng 61
home network
Home MSC
PSTN
correspondent
MSC
anchor MSC
MSCMSC
(b) sau khi handoff
GSM: handoff between MSCs
anchor MSC: MSC u tin trong sut cuc gi cuc gi duy tr route
thng qua anchor MSC
cc MSC mi thm vo cui dy chuyn MSC ging nh thit b di ng di chuyn vo MSC mi
IS-41 cho php ty chn ti thiu ha thu ngn ng i gia cc dy chuyn MSC
Cc mng khng dy v di ng 62
GSM vi Mobile IP
GSM Ch thch Mobile IPHome system Mng cha cc s in thoi c nh ca user
di ngHome network
Gateway Mobile Switching Center, home MSC. HLR
Home MSC: im tip xc ly c a ch route. HLR: c s d liu trong home MSC cha s t c nh, thng tin b sung, v tr hin ti ca user di ng
Home agent
Visited System Mng khc vi h thng home, trong user di ng ang thng tr
Visited network
Visited Mobile services Switching Center.Visitor Location Record (VLR)
Visited Mobile: p ng cho vic thit lp cuc gi n/t thit b di ng trong cc cell kt ni vi MSC. VLR: dng ng k tm thi trong h thng visited, cha thng tin ng k ca mi user
Foreign agent
Mobile Station Roaming Number (MSRN), roaming number
a ch c th route cho mi on cuc gi t gia home MSC v visited MSC,
Care-of-address
Cc mng khng dy v di ng 63
Khng dy, di ng: nh hng n cc giao thc lp cao hn
nh hng s l ti thiu
m hnh dch v hng hiu qu tt nht gi nguyn khng thay i
TCP v UDP c th (v ang hin thc) chy trn mng khng dy, di ng
nhng hiu qu:
gi mt/tr v cc li bit (cc gi b hy, tr v truyn li) v handoff
tr lm suy gim lu thng thi gian thc
bng thng gii hn ca cc kt ni khng dy