OSPF E2 routes

Just curious, why does OSPF default to E2 routes for external routes? I would think it would make more sense to include the cost of links internal to the domain to the metric for external routes. Wouldn't that provide a more accurate representation of an external route? No big deal, but if E2 is default there must be some advantage to doing so...

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dtlokee

Less processing overhead because changes in the internal network won't affect the external routes (other than reachability). Depending on the network topology there may not be much of a requirement to have the cost to the ASBR included in the metric.

Mrock4

dtlokee wrote:

Less processing overhead because changes in the internal network won't affect the external routes (other than reachability). Depending on the network topology there may not be much of a requirement to have the cost to the ASBR included in the metric.

I was wondering the same actually. That really makes sense though. I guess that little CCIE cert does teach you a thing or two. Thanks man.

dtlokee

Mrock4 wrote:

dtlokee wrote:

Less processing overhead because changes in the internal network won't affect the external routes (other than reachability). Depending on the network topology there may not be much of a requirement to have the cost to the ASBR included in the metric.

I was wondering the same actually. That really makes sense though. I guess that little CCIE cert does teach you a thing or two. Thanks man.

Now I'm just gonna give out wrong answers and see if anyone questions me

cisco_trooper

dtlokee wrote:

Mrock4 wrote:

dtlokee wrote:

Less processing overhead because changes in the internal network won't affect the external routes (other than reachability). Depending on the network topology there may not be much of a requirement to have the cost to the ASBR included in the metric.

I was wondering the same actually. That really makes sense though. I guess that little CCIE cert does teach you a thing or two. Thanks man.

Now I'm just gonna give out wrong answers and see if anyone questions me

LOL. Please don't. You'll hurt my feeble little brain.

Mrock4

cisco_trooper wrote:

LOL. Please don't. You'll hurt my feeble little brain.

I second that..

Nah, I don't think you'd do that dt..see, the problem is, you would feel guilty misleading fellow networking specialists...right?

For what it's worth, now I feel like reading some of the Cisco doc CD...look for those little obscure details that I don't know.

jezg76

I like the fact that if there is a route with both an E1 and an E2 route it will choose the E1 path. I guess that does make sense in the grander scheme, but it sure does add to the fun, that which is OSPF.

My camp instructor said the CCNA is just the tip of the iceberg with OSPF. Boy was he right...