eigrp-or-ospf-which-should-i-use

EIGRP or OSPF – Which should I use?

Kevin Delgadillo, PLM, IP Routing, NSSTG

Ernie Mikulic, PM, OSPF, PfR, SAF

Which routing protocol is better?

Which routing protocol should I use in my network?

Should I switch from the one I’m using?

The Questions

 The answer is yes if:

The network is complex enough to “bring out” a protocol’s specific advantages

You can define a specific feature (or set of features) that will benefit your network tremendously…

The Questions

But, then again, the answer is no! 

Every protocol has

some features and not others, different scaling

properties, etc.

Let’s consider some specific topics for each protocol....

EIGRP or OSPF: Which Routing Protocol?

Link State & Distance Vector

Convergence Speed

Topology and Heirarchy

Summary

Link State & Distance Vector

Link state

•OSPF is an example

•Each router tells the world about its neighbors

•All information passed is connectivity related

•Each node in the network constructs a connectivity map of the network

•Each node keeps identical link-state database from which routing table is derived

•More complex than distance vector protocols

Distance vector

•EIGRP is an example (but does not behave like a “pure” DV protocol)

•Each router tells its neighbors about its world

•Each node shares its routing table with its neighbors

•Simpler than link state protocols

Convergence Speed

Equal Cost Convergence

OSPF Convergence

EIGRP Convergence

Convergence Summary

Convergence Speed

Which protocol converges faster?

OSPF verses EIGRP

Is DUAL faster, or Dijkstra SPF?

 Rules of Thumb

The more routers involved in convergence, the slower convergence will be

The more routes involved in convergence, the slower convergence will be

Convergence Speed

 Three steps to convergence

Detect the failure

Calculate new routes around the topology change Add changed routing information to the routing table

The first and third steps are similar for any routing protocol, so we’ll focus on the second step