McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Chapter 14 Routing Protocols RIP, OSPF, BGP

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Figure 14-1 Autonomous systems

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Figure 14-2 Popular routing protocols Distance Vector Link State Path Vector

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Distance Vector Routing. Forouzan + CCNA: Slow convergence. Routing loops. Counting to infinity. Split horizon Route poisoning. Triggered update.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 RIP: Routing Information Protocol 14.3 Exposición equipo 5

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Example of updating a routing

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Initial routing tables in a small autonomous system

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Final routing tables for the previous figure

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 RIP message format

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Request messages

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Example 1 What is the periodic response sent by router R1 in Figure 13.8 (next slide)? Assume R1 knows about the whole autonomous system.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Example 1

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Solution R1 can advertise three networks , , and The periodic response (update packet) is shown in Figure 13.9 (next slide).

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Solution to Example 1

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 RIP timers

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Example 2 A routing table has 20 entries. It does not receive information about five routes for 200 seconds. How many timers are running at this time?

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Solution The timers are listed below: Periodic timer: 1 Expiration timer: 20  5  15 Garbage collection timer: 5

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Slow convergence

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Hop count

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Instability

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Split horizon

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Poison reverse

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 RIP-v2 Format

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 RIP version 2 supports CIDR.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Authentication

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 RIP uses the services of UDP on well-known port 520.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 OSPF: Open Shortest Path First 14.5

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Areas in an autonomous system

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Types of links

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Point-to-point link

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Transient link

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Stub link

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Example of an internet

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Graphical representation of an internet

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Types of LSAs

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Router link

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Network link

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Summary link to network

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Summary link to AS boundary router

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 External link

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Example 3 In Figure (next slide), which router(s) sends out router link LSAs?

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Figure Example 3 and Example 4

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Solution All routers advertise router link LSAs. R1 has two links, Net1 and Net2. R2 has one link, Net2 in this AS. R3 has two links, Net2 and Net3.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Example 4 In Figure 14.31, which router(s) sends out the network link LSAs?

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Solution All three network must advertise network links: Advertisement for Net1 is done by R1 because it is the only router and therefore the designated router. Advertisement for Net2 can be done by either R1, R2, or R3, depending on which one is chosen as the designated router. Advertisement for Net3 is done by R3 because it is the only router and therefore the designated router.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 In OSPF, all routers have the same link state database.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Shortest path calculation Dijkstra algorithm Start Stop Set root to local node and move it to tentative list Among nodes in tentative list, move the one with the shortest path to permanent list. Tentative list is empty? Add each unprocessed neighbor of last moved node to tentative list if not already There. If neighbor is in the tentative list with larger cumulative cost, replace with new one. No Yes

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Shortest path calculation Dijkstra algorithm

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 F 0

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 F N3 N

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 F N3 N

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 F DE N3 N

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 F A DE N3 N

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 F A DE B N3 N5 N

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 F A DE B N3 N5 N

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 F A DE B N3 N5 N4 N

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 F A DE B N3 N5 N4 N

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 C 20 F A DE B N3 N5 N4 N

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 C N F A DE B N3 N5 N4 N

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 F A DE B C N3 N5 N4 N1 N

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Types of OSPF packets

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 OSPF packet header

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Hello packet

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Database description packet

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Link state request packet

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Link state update packet

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 LSA header

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Router link LSA

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Example 5 Give the router link LSA sent by router in Figure

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Figure Example 5

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Solution This router has three links: two of type 1 (point-to- point) and one of type 3 (stub network). Figure shows the router link LSA.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Figure Solution to Example 5

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Network link advertisement format

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Example 6 Give the network link LSA in Figure

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Figure Example 6

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Solution The network, for which the network link advertises, has three routers attached. The LSA shows the mask and the router addresses. See Figure Note that only one of the routers, the designated router, advertises the network link.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Figure Solution to Example 6

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Summary link to network LSA

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Summary link to AS boundary LSA

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 External link LSA

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Link state acknowledgment packet

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 OSPF packets are encapsulated in IP datagrams.