EIGRP Question

Hello all

When you see the comment below about EIGRP, what do you think they are referring to? I just wanted to get your opinions on particularly that first sentence?

Propagation of partial updates is automatically bounded so that only those routers that need the information are updated. As a result of these two capabilities, EIGRP consumes significantly less bandwidth than IGRP.

Thanks

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Comments

mapletune

That probably means, unlike IGRP (sends broadcast to every single port to propagate/spread the route table), EIGRP sends updates that are "bounded"/limited to multicast for routers. Also, unlike IGRP that sends the whole table, EIGRP sends only topology change updates.

Thus,

1. broadcast vs multicast. EIGRP consumes less bandwidth.
2. sending the whole routing table vs sending routing updates. EIGRP consumes less bandwidth.

hope i got that right =p
Cheers

fluk3d

mapletune wrote: »

That probably means, unlike IGRP (sends broadcast to every single port to propagate/spread the route table), EIGRP sends updates that are "bounded"/limited to multicast for routers. Also, unlike IGRP that sends the whole table, EIGRP sends only topology change updates.

Thus,

1. broadcast vs multicast. EIGRP consumes less bandwidth.
2. sending the whole routing table vs sending routing updates. EIGRP consumes less bandwidth.

hope i got that right =p
Cheers

EIGRP

- Instead of sending the complete IP routing table, EIGRP sends incremental updates when network changes occur.
- EIGRP over NBMA networks also needs to be designed carefully as by default it uses 50% of the available traffic
- EIGRP can also be setup to support unicast exchange with neighbors as suppose to using multicast

jeanathan

Propagation of partial updates is automatically bounded so that only those routers that need the information are updated. As a result of these two capabilities, EIGRP consumes significantly less bandwidth than IGRP.

My thoughts:

Automatically bounded = you are not sending the packets on interfaces not bounded to the eigrp routing process (interfaces that have no network address in the ranges configured using the eigrp "network" command...

Yep broadcasting on all interfaces with igrp means it was not a very flexible, effecient, and scalable protocol.

Also and you need to do more research because I do Microsoft and not Cisco for my job (Recertifing CCNP before May 2013 with CCNP route). But there are other reasons for updates not to be sent. I have not dug that deep into the protocol to know yet what other circumstances result in "automatically" not bound other than EIGRP not being enabled on the interface.

By default, EIGRP will limit itself to using no more than 50% of the interface bandwidth. -- Configuration Notes for the Implementation of EIGRP over Frame Relay and Low Speed Links - Cisco Systems

Updates are used to convey reachability of destinations. When a new neighbor is discovered, update packets are sent so the neighbor can build up its topology table. In this case, update packets are unicast. In other cases, such as a link cost change, updates are multicast. Updates are always transmitted reliably.
-- Introduction to EIGRP [IP Routing] - Cisco Systems