Routing 1 Autonomous System 1 Autonomous System 2

Routing 1

Autonomous System 1 Autonomous System 2 Subnet 1. 2 R 3 Subnet 2. 1 R 2 R 6 Subnet 1. 1 Subnet 1. 3 R 5 Subnet 2. 2 R 7 R 1 R 4 Subnet 1. 4 R 8 Subnet 2. 4 Subnet 2. 3 LEGEND: Interior Gateway Protocol Exterior Gateway Protocol 3

라우팅 프로토콜의 분류 Interior Gateway Protocol (IGP) Exterior Gateway Protocol (EGP) 4

IGP Routing protocol Shortest path algorithm Routing algorithm RIP IGRP Bellman-Ford algorithm Distance Vector algorithm OSPF IS-IS Dijstra algorithm Link State algorithm 5

각 라우터에 이르는 시간의 계산 B Echo 패킷 A J m sec (TAB, TAC, TAD, TAE) TB = m + TAB T C = m + T AC T D = m + T AD T E = m + T AE Ti sec C D E 7

Distance Vector Algorithm의 예 8

Updating routing table 9

Link State Packet의 구성 11

Link state routing의 예(1) Step 1: 이웃 노드로부터 링크 상태 정보(link state information)를 모아서 링크 상태 패킷(link state packet)들 을 만든다. 5 B 2 A 2 2 C 3 1 3 D F 1 1 3 E Link state packets A seq# age B 2 C 5 D 2 B seq# age A 2 C 3 D 2 C seq# age A 5 B 3 D 3 E 1 F 1 D seq# age A 2 B 2 C 3 E 1 E seq# age C 1 D 1 F seq# age C 1 E 1 12

Link State Database 5 B 2 A 3 2 2 C 3 D 1 F 1 3 1 E Link # Cost A-B A-C A-D B-A B-C B-D C-A 2 5 2 2 3 2 5 C-B C-D C-E C-F D-A D-B D-C 3 3 1 1 2 2 3 D-E E-C E-D E-F E-C E-E 1 1 1 14

BGP 예(1) AS 1 N 1 AS 2 N 2 R 1 N 3 1 R 2 1 R 51 AS 3 R 3 AS 5 R 52 R 4 AS 4

BGP 예(3) AS 1 N 1 AS 2 N 2 R 1 N 3 R 2 2 R 51 AS 3 R 3 AS 5 2 R 52 R 4 AS 4

BGP 예(4) n R 2은 R 51에게 다음의 정보를 포함한 UPDATE message를 보낸다. n n AS_Path: {AS 1, AS 2} Next_Hop : {R 2’s IP address} NLRI: {N 1, N 2, N 3} R 3는 R 4에게 다음의 정보를 포함한 UPDATE message를 보낸다. n n n AS_Path: {AS 1, AS 3} Next_Hop : {R 3’s IP address} NLRI: {N 1, N 2, N 3}

BGP 예(5) AS 1 N 1 AS 2 N 2 R 1 N 3 R 2 R 51 AS 3 R 3 AS 5 3 R 4 AS 4 R 52

BGP 예(6) n R 4는 R 52에게 다음의 UPDATE message를 보낸다. n n n AS_Path: {AS 1, AS 3, AS 4} Next_Hop : {R 3’s IP address} NLRI: {N 1, N 2, N 3}

BGP 예(7) AS 1 N 1 AS 2 N 2 R 1 N 3 R 2 R 51 AS 3 R 3 AS 5 R 52 R 4 AS 4