EIGRP

1. EIGRP LSNDI RMRA MM Clements

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! LSNDI 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 LSNDI 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 LSNDI 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 = (107/ BW) x 256 • EIGRP delay = (delay/10) x 256 • Max hop = 224 c.f. IGRP 256 LSNDI 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 LSNDI 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 LSNDI 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 224.0.0.10 • Smooth Round Trip Timer SRTT LSNDI 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 neighbour’s transmissions (not hellos) • Supports reliable, sequenced delivery of packets (like TCP) but using Reliable Transport Protocol (RTP) LSNDI RMRA

10. Neighbour Table LSNDI 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 LSNDI 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 (2195458/ 281400) LSNDI RMRA

13. 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) LSNDI 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 LSNDI RMRA

15. LSNDI 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 LSNDI RMRA

17. Neighbour Discovery and Rediscovery LSNDI RMRA

18. 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 LSNDI RMRA

19. 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 LSNDI 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 65535 • See RFC 1930 LSNDI RMRA

21. Setting up EIGRP Needs Autonomous System Number Router(config)#router eigrp 123 Router(config-router)#net 192.168.1.1 0.0.0.3 Router(config-router)#net 22.22.22.0 0.0.0.255 Router(config-router)#exit Uses Wildcard Mask LSNDI 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 LSNDI 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: 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 LSNDI RMRA

24. Debugging EIGRP Router#debug eigrp ? fsm EIGRP Dual Finite State Machine events/actions packets EIGRP packets LSNDI 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 192.168.1.2 AS 123, Flags 0x0, Seq 26/0 idbQ 0/0 EIGRP: Received HELLO on Serial0/0/1 nbr 192.168.1.6 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 LSNDI 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 LSNDI RMRA