network boundary

[carl_townshend]

can anyone define this ? I am unsure what it means with respect the eigrp !!

summarization would only occur when routes cross a network boundary

[mheusinger]

Hello,

this probably refers to classful addressing (class A, B, C, ...). EIGRP will - by default - create a summary route when an update crosses a network boundary. Example with 3 routers R1, R2 and R3 running EIGRP:

10.1.1.0/24 - R1 - 10.1.2.0/24 - R2 - 192.168.1.0/24 - R3

In this example R2 would anounce 10.0.0.0/8 to R3, because the update "leaves" the 10.0.0.0/8 network and "enters" into 192.168.1.0/24.

You can avoid this by configuring "no auto-summary" in EIGRP.

Hope this helps! Please rate all posts.

Regards, Martin

[carl_townshend]

so basically the boundary is when it changes ip say from the 10 to the 192 network ?

thanks

[pkhatri]

Yes... the boundary referred to here is the old classful boundary. So if you go from a 172.16.5.0/24 network to a 172.16.200.0/24 network, that will not be considered a network boundary since both of those networks are part of the class B network of 172.16.0.0/16. It has to cross classful boundaries...

So your example of going from a 10.x.x.x network to a 192.x.x.x network constitutes a case where this applies.

Pls remember to rate posts.

Paresh

[mheusinger]

Hello Carl,

yes a boundary would be between one classful network and another like 10/8 to 172.16/16 or 192.168.1.0/24 to 123.123/16 and so on.

Hope this helps! Please rate all posts.

Regards, Martin

[carl_townshend]

So no matter what mask you use then, unless you use the no auto summary command when it crosses boundaries it will just advertise the 10/8 network even though you might have multiple 10 /24 networks behind that router in which case it wont be able to find them ?

thanks