Chapter 7Enhanced IGRP (EIGRP) and Open Shortest Path

First (OSPF)

Link State Algorithm

Sends Update when it occurs only, link state protocols deal with three types of tables, they are:

Neighbors table Topology table Route table

Open Shortest Path First (OSPF)

Allows multi-vendor deployment (Open standard) R.P Link state R.P Classless R.P Supports VLSM and discontiguous networks Has unlimited hop count Does not make auto-summery (because of using wildcard) AD = 110 “O” in Route Table Used within one autonomous system (AS 1~65535) Used with areas (2^32) Supports authentication Fast convergence

10.16.0.0/12

10.32.0.0/12

192.168.25.0/24

Router(config)#router ospf 10 (local significant)Router(config-router)#network 10.16.0.0 0.15.255.255 area 1Router(config-router)#network 10.32.0.0 0.15.255.255 area 1Router(config-router)#network 192.168.25.0 0.0.0.255 area 0

OSPF Terminology

Link Router ID RID Neighbor Router Adjacent Router Designated Router DR Backup Designated Router BDR Hello protocol Link State Advertisement LSA Neighborship database Topological database OSPF areas

DR

BDR

R2

R3 R4

R1

Why will we use areas?

I. Fast building routing table II. Decreasing overload on router III. Simpler troubleshooting

Hierarchical Design (Areas)

Neighbors table is constructed using Hello packets LSA Packets are transmitted between routers to construct Topological database Shortest path tree is constructed Dijkstra or SPF algorithm to find best for destinations with multiple paths Results go to the route table

Network Types with OSPF

1- Point to Point Hello interval= 10 sec.Dead interval= 40 sec.

2- Point-to-multipoint Hello interval= 10 sec.Dead interval= 40 sec.

3- Broadcast (multi-access)Hello interval= 10 sec.Dead interval= 40 sec.

4- Non-broadcast multi-access NBMA(Frame-Relay or X.25) Hello interval= 30 sec.Dead interval= 120 sec.

Electing DR and BDR

1- Priority (0~255); 1 by default2- Router ID:

Router(config)#int loopback 0Router(config-if)#ip add 10.0.0.1 255.0.0.0Router(config-if)#no shut

If there is only physical interface If there is loopback interface

OSPF Metric

Metric= cost= (10^8/B.W in bps) Fast Ethernet= 100MbpsCost= 10^8/(100x10^6) =1

Ethernet= 10MbpsCost= 10^8/(10x10^6) =10

Serial= 1.54MbpsCost= 10^8/(1.54410^6) =64

Router(config)#int s0Router(config-if)#ip ospf hello-interval 40 Router(config-if)#ip ospf dead-interval 160 Router(config-if)#ip ospf priority 25Router(config-if)#ip ospf cost 20

Show Commands

Router#sh ip ospf(Process ID, Area ID, RID, SPF statistics, and LSA timer information)

Router#sh ip ospf database(Process ID, Area ID, RID, Topology Table)

Router#sh ip ospf interface(Process ID, Area ID, RID, Interface IP address, Network type, Cost, Priority, DR/BDR election information (if applicable), Hello and Dead timer intervals, Adjacent neighbor information )

Router#sh ip ospf neighbor(Process ID, Area ID, RID, Neighbors table, DR/BDR information)

DR/BDR InformationFull/Full/DRFull/BDRFull/2 way DR other

Debugging OSPF

Router#debug ip ospf packetRouter#debug ip ospf helloRouter#debug ip ospf adj

Manual Summarization

172.

16.1

6.0/

20

172.

16.3

2.0/

20

10.6

4.0.

0/12

10.9

6.0.

.0/1

2

172.

16.4

8.0/

20

10.8

0.0.

0/12

10.1

12.0

.0/1

2

.3 .4

1700A 1700B 2600A 2500 2600B

.2 .2 .2

f0.2

f0.1

s0.1

s1.1

s0/0.2

s0/0.2

s0.2

s0/1.1f0/0

.1f0/0.1

e0.1

Area 1 Area 0

Manual Summarization

In Router 2600A2600A(config)#router ospf 102600A(config-router)#network 172.16.32.0 0.0.15.255 area 12600A(config-router)#network 172.16.48.0 0.0.15.255 area 12600A(config-router)#network 10.64.0.0 0.15.255.255 area 02600A(config-router)#area 1 range 172.16.0.0 255.255.192.0

Enhanced Interior Gateway Routing Protocol (EIGRP)

Cisco Proprietary R.P Hybrid (advanced distance-vector) R.P Classless R.P Supports VLSM and discontiguous networks Max. hops 255 (100 by default) Makes auto-summery by default, auto-summery can be disabled Use composite metric (B.W, Reliability, Delay, Load, MTU) AD = 90 (for internal EIGRP route), AD = 170 (for external EIGRP route) “D” in Route Table Used within one autonomous system (AS 1~65535) Best path selection via Diffusing Update Algorithm (DUAL) The only R.P that supports for IP, IPv6, IPX, and Apple Talk via protocol

dependent modules (PDM) Communication via Reliable Transport Protocol (RTP)

EIGRP Packets

1- Hello Packet2- Update Packet3- Query Packet4- Reply Packet5- Acknowledge Packet

1- Hello PacketMulticast 224.0.0.10 each (5 sec), holddown (15 sec)

2- Update Packet

Neighbors Table

Neg. IPMy Int.

Topology Table

Net1Path1 Succ

Net1Path2 F.Succ

Net1Path3 F.Succ

Net2Path1 Succ

Net2Path2 F.Succ

Net3Path1 Succ

Routing Table

Net1Path1 Succ

Net2Path1 Succ

Net3Path1 Succ

DU

AL

Alg

.D

UA

L A

lg.

DU

AL

Alg

.D

UA

L A

lg.

50 2030

40 40

Next Hop

R.D= Reported Distance

Next Hop

R.D= Reported Distance

F.D= Feasible Distance

F.D= Feasible Distance

F.D= Next Hop + R.D F.D of Succ. > R.D of F. Succ (New Succ)

3- Query PacketHolddown (180 sec), (16 x 5 sec)

4- Reply Packet

5- Acknowledge Packet

10.16.0.0/12

10.32.0.0/12

192.168.25.0/24

Router(config)#router eigrp 10 (AS)Router(config-router)#network 10.0.0.0Router(config-router)#network 192.168.25.0Router(config-router)#no auto-summery

Variance Vector

New Best Path ≤ Variance x Old Best Path

Topology Table

Net1Path1 Succ1000

Net1Path2 F.Succ1500

Net1Path3 F.Succ2000

Net1Path4 F.Succ3000

New Best Path ≤ 2 x 1000New Best Path ≤ 2000

Topology Table

Net1Path1 Succ1000

Net1Path2 F.Succ1500

Net1Path3 F.Succ2000

Net1Path4 F.Succ3000

Router(config)#eigrp 10Router(config-router)#variance 2Router(config-router)#maximum-paths 6

Manual Summarization

172.

16.1

6.0/

20

172.

16.3

2.0/

20

10.6

4.0.

0/12

10.9

6.0.

.0/1

2

172.

16.4

8.0/

20

10.8

0.0.

0/12

10.1

12.0

.0/1

2

.3 .4

1700A 1700B 2600A 2500 2600B

.2 .2 .2

f0.2

f0.1

s0.1

s1.1

s0/0.2

s0/0.2

s0.2

s0/1.1f0/0

.1f0/0.1

e0.1

IGRP EIGRP

Automatic Redistribution EIGRP with IGRP

172.

16.1

6.0/

20

172.

16.3

2.0/

20

200.

200.

200.

0/24

192.

168.

60.0

/24

172.

16.4

8.0/

20

192.

168.

50.0

/24

192.

168.

70.0

/24

.3 .4

1700A 1700B 2600A 2500 2600B

.2 .2 .2

f0.2

f0.1

s0.1

s1.1

s0/0.2

s0/0.2

s0.2

s0/1.1f0/0

.1f0/0.1

e0.1

Manual Summarization

Manual Summarization

2600A(config)#router eigrp 102600A(config-router)#network 172.16.0.02600A(config-router)#network 200.200.200.02600A(config-router)#no auto-summery2600A(config-router)#exit2600A(config)#int s0/12600A(config-if)#ip summary-address eigrp 10 172.16.0.0 255.255.192.0

Show and Debugging Commands

Router#sh ip eigrp neighborRouter#sh ip eigrp topologyRouter#sh ip routeRouter#sh ip route ripRouter#sh ip route igrpRouter#sh ip route ospfRouter#sh ip route eigrpRouter#debug eigrp packetRouter#debug ip eigrp notificationRouter#clear ip route *