eigrp lsndi rmra mm clements. 4 feb 2008lsndi rmra 2 last week ……… ospf requires more...

EIGRP

LSNDI RMRA

MM Clements

LSNDI RMRA2 4 Feb 2008

Last Week ………

OSPF requires more resources from router Fast convergence Less overhead – good for large networks LSAs sent in LSUs – only the changes are

flooded to the network Supports VLSM Complex to configure!


This week……….

EIGRP – Cisco proprietary routing protocol Key features Neighbor and topology tables Feasible Distance & Successor Routes EIGRP packet types Setting up EIGRP


Enhanced Interior Gateway Protocol

Released in 1994 as successor to IGRP Compatible with IGRP Hybrid routing protocol with best of distance

vector & link-state algorithms Uses partial updates and neighbour discovery Like OSPF but easier to configure Good for large multiprotocol networks that

primarily use Cisco routers


EIGRP

Offers multiprotocol operation (IP, IPX etc) EIGRP multiplies IGRP metric by 256 Uses 32-bit metric c.f. IGRP 24-bit metric Metric = bandwidth/ delay EIGRP BW = (107/ BW) x 256 EIGRP delay = (delay/10) x 256 Max hop = 224 c.f. IGRP 256


EIGRP key features

EIGRP automatically shares routing information with IGRP and vice versa

EIGRP tags routes from other protocols as external Rapid convergence from Diffused Updating Algorithm

(DUAL) Guaranteed no loops – all routers running EIGRP update

at the same time if change occurs Efficient use of BW – partial incremental updates only Sent only to routers that need information – not all

routers


Good use of Network Bandwidth

Partial bounded updates, unlike OSPF No timed routing updates RIP = 30s; IGRP = 90s – full routing tables EIGRP uses small hello packets Unreliable – no acknowledgements Supports VLSM & CIDR unlike IGRP Uses PDMs to support IP, IPX, Appletalk


EIGRP Router Tables

Neighbour table lists adjacent routers One neighbour table per supported protocol Similar to OSPF adjacency database Holds neighbour address and interface data Hold time = time to wait before considering

neighbour to be ‘down’ = 3 x hello interval– Multicast to 224.0.0.10

Smooth Round Trip Timer SRTT


Neighbour Table Contents

Queue Count (Q Cnt) = number of packets waiting in queue to be delivered

If Q Cnt > 0 means possible congestion problem Sequence number (Seq No) to keep track of

neighbour’s transmissions (not hellos) Supports reliable, sequenced delivery of packets

(like TCP) but using Reliable Transport Protocol (RTP)


Neighbour Table


Topology Table

Made up of all EIGRP routing tables in AS DUAL takes data from neighbour and topology

tables to calculate lowest cost routes Allows EIGRP to identify & switch to alternative

routes quickly Primary (successor) route placed in topology

table Also keeps a backup route if available


In Topology Table are…

Feasible Distance (FD) – lowest calculated metric to each destination

Route Source – identifies number of router that identified the route originally

Reported distance (RD) – distance an adjacent router reports to a specific destination

FD RD (2195458/ 281400)


Also in Topology table….

Interface information – identifies the router’s interface to reach a given destination

Route status – Passive (P) for a stable route Active (A) if DUAL is recalculating route Successor is primary route to destination Feasible successor is placed below successor as

a backup route to be used when topology changes (saves total recalculation of routing)


Successor Routes

Appear in Topology and Routing table Can be up to 4 successor routes to a destination Can be of equal or unequal cost FS identified at same time as successors Only kept in Topology table Not mandatory to have FS If successor route goes down, lowest FS chosen


Identifying Routes

If no FS, router places Active status on a route Sends Query packets to all neighbours Neighbours reply with successor or no successor Passive status placed on route if positive reply DUAL always tries to identify a FS in case of

problems – saves querying neighbours and recalculations


Neighbour Discovery and Rediscovery


Reliable Transport Protocol

RTP guarantees ordered delivery of routing packets using sequence numbers

EIGRP is protocol independent – doesn’t need IP RTP used to multicast and unicast packets


EIGRP Packet Types

Hello – sent on 1.544 Mbps or less every 60s Acknowledgement = data-less hello packet Update – sent to newly discovered neighbour Query – multicast or unicast Reply – response to a query


Autonomous System Number

An Autonomous System (AS) is a set of networks and routers under the control of one body

This system has a common routing policy as presented to the Internet

ASs are given unique numbers between 1 and 65535

See RFC 1930


Setting up EIGRP

Needs Autonomous System Number

Router(config)#router eigrp 123Router(config-router)#net 192.168.1.1 0.0.0.3Router(config-router)#net 22.22.22.0 0.0.0.255Router(config-router)#exit

Uses Wildcard Mask


Verifying EIGRP

Router#show ip protocols This shows the routing protocol in use and other

useful information too

Router#sh ip eigrp ? interfaces IP-EIGRP interfaces neighbors IP-EIGRP neighbors topology IP-EIGRP Topology Table traffic IP-EIGRP Traffic Statistics


Router#sh ip pro

Routing Protocol is "eigrp 123 " Outgoing update filter list for all interfaces is not set Incoming update filter list for all interfaces is not set Default networks flagged in outgoing updates Default networks accepted from incoming updates EIGRP metric weight K1=1, K2=0, K3=1, K4=0, K5=0 EIGRP maximum hopcount 100 EIGRP maximum metric variance 1 Redistributing: eigrp 123 Automatic network summarization is in effect Automatic address summarization: Maximum path: 4 Routing for Networks: 192.168.1.0/30 22.22.22.0/24 192.168.1.12/30 Routing Information Sources: Gateway Distance Last Update 192.168.1.1 90 864844 192.168.1.13 90 4096070 Distance: internal 90 external 170


Debugging EIGRP

Router#debug eigrp ? fsm EIGRP Dual Finite State Machine events/actions

packets EIGRP packets


Debug output

Router#debug eigrp paEIGRP Packets debugging is on (UPDATE, REQUEST, QUERY, REPLY, HELLO, ACK )Router#EIGRP: Received HELLO on Serial0/0/0 nbr 192.168.1.2 AS 123, Flags 0x0, Seq 26/0 idbQ 0/0EIGRP: Received HELLO on Serial0/0/1 nbr 192.168.1.6 AS 123, Flags 0x0, Seq 20/0 idbQ 0/0EIGRP: Sending HELLO on FastEthernet0/0 AS 123, Flags 0x0, Seq 22/0 idbQ 0/0 iidbQ un/rely 0/0EIGRP: Sending HELLO on Serial0/0/1 AS 123, Flags 0x0, Seq 22/0 idbQ 0/0 iidbQ un/rely 0/0

Remember to turn of debugging when you have finished undebug all will turn off all debugging processes


Summary

EIGRP similar to OSPF - – Has neighbour table– Sends hello packets

Has topology table (1 for each protocol) Uses DUAL on Neighbour & Topology tables Elects successors and feasible successors (FS) FS used in times of trouble – fast selection Verification and debug commands

eigrp lsndi rmra mm clements. 4 feb 2008lsndi rmra 2 last week ……… ospf requires more...

Documents