Bao Cao Giao Thuc Dinh Tuyen OSPF Diendandaihoc.vn 03242725112011

8/2/2019 Bao Cao Giao Thuc Dinh Tuyen OSPF Diendandaihoc.vn 03242725112011

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LOGO

Giao thc nh tuyn OSPFv m phng

in t 5-K50

Nhm SV thc hin:

1. Nguyn Quang Dng.

2. Nguyn c Khoa.3. Minh Sn.4. Hong Hoi Nam.5. Nguyn Vit Ton.


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Mc lc

Mc lc1. nh tuyn.1.1. Khi nim nh tuyn.

1.2.Cc kiu nh tuyn.

2. Giao thc nh tuyn OSPF:2.1. Khi nim OSPF.

2.2.OSPF Message.

2.3. OSPF Packet Header.

2.4. Thit lp Neighbour.2.5. Thut ton trong OSPF.

2.6.LSA.

2.7 DR v BDR trong mi trng a truy cp.

3.M phng bng Packet Tracer.2

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nh tuyn

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Routing.

Khi nim nh tuyn (Routing):

- nh tuyn l qu trnh chn la cc ng i trn mt

mng my tnh gi d liu qua .

- nh tuyn ch ra hng, ng i tt nht (best path)tngun n ch ca cc gi tin (packet) thng qua cc node trung

gian l cc router.

-C 2 loi nh tuyn: tnh v ng.

-Trong nh tuyn tnh,sau khi cu hnh ng i l c nh.

Khi c thay i trong mng phi cu hnh li. Ph hp vi mng

nh.Rt kh trin khai trong mng ln.

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Dynamic Routing:

Dynamic Routing:

- nh tuyn ng chim u th trn mngInternet ngy nay. Cc ng i t ng c cpnht bi router. ng i n ch c tnh linhhot.

Cc kiu nh tuyn ng:

1. RIP(Routing Information Protocol).

2. IGRP(Interior Gateway Routing Protocol)

3. EIGRP(Enhanced IGRP)4. OSPF(Open Shortest Path First)

5. IS-IS(Intermediate System-to-Intermediate System )

6. BGP (Border Gateway Protocol).

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Dynamic Routing:

Cc thut ton tm ng:

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1.OSPF.2. IS-IS.

1. RIP (ver 1 &2).2. IGRP.3. EIGRP.

Distance Vector Link State


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Khi nim OSPF:

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OSPF l giao thc nh tuyn dng Link-State da trn chun m c

pht trin thay th phng thc Distance Vector (RIP).OSPF ph hp vi mng ln, c kh nng m rng, khng b loop trongmng.u im ca OSPF:

1. Tc hi t nhanh.2.H tr mng con (VLSM).

3.C th p dng cho mng ln.4.Chn ng theo trng thi ng link hiu qu hn distance vector.5. ng i linh hot hn.6.H tr xc thc (Authenticate).

Trong 1 h thng dng disistance vector (RIP) th mt mng ch qu 15router th khng th n c. iu ny lm kch thc mng dng RIP nh,

kh nng m rng km. OSPF th khng b gii hn v kch thc, tng khnng m rng.OSPF c th cu hnh theo nhiu vng (area), bng cch ny c th giihn lu thng trong tng vng. Thay i vng ny khng nh hng n vngkhc . Do vy kh nng m rng rt cao.


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Lch s pht trin giao thc OSPF:

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1989 1991 1998 1999

Qu trnh pht trin OSPF (bt u nghin cu t 1987).OSPFc m t trong chun ca IETF (Internet Engineering Task Force).OSPF c tnh m (cng cng), khng mang tnh c quyn


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OSPF Message.

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- Mt OSPF Message c ng gi


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OSPF Packets:

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Cc loi gi tin OSPF:1.Hello: Khi to kt ni vi router OSPF khc.

2.DBD (Database description): cha danh sch ngn gn

database cc router link-state, kim tra tnh ng b d liu

gia cc router.3.LSR(Link State Request): Yu cu router gi nhiu

thng tin v trng thi ng link.

4.LSU(Link State Update): Gi tin tr li li LSR, cha cc

gi qung b Link-State.

5.LSAck: Khi LSU c nhn, LSAck s c gi.


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OSPF Packet Header:

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Thit lp Neighbor

Trc khi Router truyn trng thi ng link ca n,n cn phi bit

cc router neighbor bng cch gi gi tin Hello.


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Thut ton trong OSPF:

Khi Router nhn c cc gi LSA, n s xy dng link-state

database v dng thut ton Dijkstra's shortest path first (SPF) to ra

SPF tree.Khi nhn thng tin mng thay i tnh li SPF.


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OSPF Metric:

Gi tr c s OSPF tnh ton ng i (OSPF metric) l cost


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Link-State Update (LSA)

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Khi OSPF c khi to hoc c thay i trong mng, cc Router Ospf struyn LSA trn mng.Gi LSA s truyn n tt c cc router trong mng


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DR & BDR

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Chn DR & BDR gii quyt vn LSA b gi i trn lan trong mng nhhng n bandwidth.

Trong mi trng a truy cp, OSPF s chn 1 router c ch nh

(Designated Router) thu thp v qung b cc gi LSA. Mt router d

phng khi DR b li (Backup Designated Router). Cc Router khc s lDROther .

Thay v gi trn lan trong mng, cc Router ch gi LSA n DR v DBR.

Sau DR s gi LSA ca Router 1 n cc Router khc .

Cc Router (DROther) gi LSA n DR & BDR thng qua a ch multicast( 224.0.0.6 ).

DR li gi LSA n cc router khc thng qua a ch multicast 224.0.0.5.


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Hot ng ca DR

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C ch hot ng ca DR.


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La chn DR & BDR:

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Qu trnh chn la DR v BDR s theo quy tc sau:1. DR :Router c s priority cao nht.2. BDR : Router c s priority cao th 2.3. Trong trng hp cc Router c s priority bng nhau th

Router c s ID (router ID)cao nht s lm DR.


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La chn DR & BDR:

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Qu trnh chn DR & BDR c tin hnh ngay khi cng ca Router u

tin c ni vo mng a truy cp v c cu hnh giao thc OSPF.

Qu trnh ny c th mt vi pht, sau khi tt c Router c bt, Routervi s ID ln nht c th l DR.

Router ID: Dng chn DR & BDR trong mng. Router ID n gin l

a ch IP, n l duy nht vi mi Router. N c l chn nh sau: 1. Cu hnh trc tip t Admin.2. Nu khng c cu hnh, s chn a ch IP ln nht ca

cng o (loopback interface).3. Nu khng c loopback interface, a ch IP ln nht ca cng

vt l (ang hot ng) s c chn lm Router ID.

Khi DR c chn, n s vn l DR cho n khi cc iu kin sau xy ra:1. Router DR b li.2. OSPF trn DR b li..3. Cng (interface) trn DR b li.

/ /


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Thay i DR & BDR

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Trong trng hp DR b li, BDR s lm DR v s c tin trnh la

chn chn ra Router mi lm BDR.

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Thay i DR & BDR

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Khi c Router c a ch IP ln nht tham gia vo mng th DR v BDR vn

khng thay i (khng chn li DR, BDR).

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Thay i DR & BDR

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Nu Router DR c ht li, tham gia vo mng th vn b coi l DROther

(Router thnh vin).

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Thay i DR & BDR

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Khi Router BDR b li, mt tin trnh s chn la cc router cn li (trDR) lm BDR (vi Router ID ln nht).

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Thay i DR & BDR

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Ch khi c DR v BDR b li, OSPF s tin hnh tnh ton la chnli DR v BDR.

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M phng

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