EIGRP LSNDI RMRA MM Clements

4 Feb 2008LSNDI RMRA 2 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!

4 Feb 2008LSNDI RMRA 3 This week………. EIGRP – Cisco proprietary routing protocol Key features Neighbor and topology tables Feasible Distance & Successor Routes EIGRP packet types Setting up EIGRP

4 Feb 2008LSNDI RMRA 4 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

4 Feb 2008LSNDI RMRA 5 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 = (10 7 / BW) x 256 EIGRP delay = (delay/10) x 256 Max hop = 224 c.f. IGRP 256

4 Feb 2008LSNDI RMRA 6 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

4 Feb 2008LSNDI RMRA 7 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

4 Feb 2008LSNDI RMRA 8 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 Smooth Round Trip Timer SRTT

4 Feb 2008LSNDI RMRA 9 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 neighbours transmissions (not hellos) Supports reliable, sequenced delivery of packets (like TCP) but using Reliable Transport Protocol (RTP)

4 Feb 2008LSNDI RMRA 10 Neighbour Table

4 Feb 2008LSNDI RMRA 11 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

4 Feb 2008LSNDI RMRA 12 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 ( / )

4 Feb 2008LSNDI RMRA 13 Also in Topology table…. Interface information – identifies the routers 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)

4 Feb 2008LSNDI RMRA 14 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

4 Feb 2008LSNDI RMRA 15

4 Feb 2008LSNDI RMRA 16 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

4 Feb 2008LSNDI RMRA 17 Neighbour Discovery and Rediscovery

4 Feb 2008LSNDI RMRA 18 Reliable Transport Protocol RTP guarantees ordered delivery of routing packets using sequence numbers EIGRP is protocol independent – doesnt need IP RTP used to multicast and unicast packets

4 Feb 2008LSNDI RMRA 19 EIGRP Packet Types Hello – sent on 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

4 Feb 2008LSNDI RMRA 20 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 See RFC 1930

4 Feb 2008LSNDI RMRA 21 Setting up EIGRP Needs Autonomous System Number Router(config)#router eigrp 123 Router(config-router)#net Router(config-router)#net Router(config-router)#exit Uses Wildcard Mask

4 Feb 2008LSNDI RMRA 22 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

4 Feb 2008LSNDI RMRA 23 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: / / /30 Routing Information Sources: Gateway Distance Last Update Distance: internal 90 external 170

4 Feb 2008LSNDI RMRA 24 Debugging EIGRP Router#debug eigrp ? fsm EIGRP Dual Finite State Machine events/actions packets EIGRP packets

4 Feb 2008LSNDI RMRA 25 Debug output Router#debug eigrp pa EIGRP Packets debugging is on (UPDATE, REQUEST, QUERY, REPLY, HELLO, ACK ) Router# EIGRP: Received HELLO on Serial0/0/0 nbr AS 123, Flags 0x0, Seq 26/0 idbQ 0/0 EIGRP: Received HELLO on Serial0/0/1 nbr AS 123, Flags 0x0, Seq 20/0 idbQ 0/0 EIGRP: Sending HELLO on FastEthernet0/0 AS 123, Flags 0x0, Seq 22/0 idbQ 0/0 iidbQ un/rely 0/0 EIGRP: 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

4 Feb 2008LSNDI RMRA 26 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