Differene between E1 & E2 Routes in OSPF

[bava_ccna]

When i look at the routing table of my OSPF router it shows lot of E1 and E2 routes.What is E1 and E2 routes.whate is the difference between them

Regards

Bava

[Harold Ritter]

Bava,

Please refer to the following document to find out what are the differences between the E1 and E2.

http://www.cisco.com/warp/public/104/3.html

Regards,

[bvsnarayana03]

E1 routes indicate cumulative cost to reach the destination i.e. int indicates cost to reach ASBR + cost to destination from ASBR.

E2 route reflects cost only from the ASBR to destination. This is the default used by ospf for redistribution.

[cisco_lad2004]

And if I may add to above replies, E2 is the default for redistribured routes.

HTH

Sam

PS:apologies , this was already covered.

[DariushEzati5665]

Hello

Why E2 is the default ????

[Joseph W. Doherty]

Hmm, don't know if something like "why" is documented by the OSPF group, but two possible reasons come to mind.

First, probably reduces some CPU load on the router, as it doesn't also have to calculate "cost" for an external route.  (NB: CPU was a lot more constrained when these standards were initially done, then they are today.)

Second, possibly an assumption that you don't often have multiple paths to the ASBR, so often no need for a "cost" calculation at all.

[DariushEzati5665]

Very good

Tanx for answer