From: Jorge
Date: Sat Dec 28 2002 - 18:55:13 GMT-3
Thanks for clearing this.
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Joe Chang
Sent: Saturday, December 28, 2002 12:08 PM
To: ccielab@groupstudy.com
Subject: Re: Redistribution EIGRP/ISIS
True, without route filtering the network in Doyle's example will not
suffer
any sub-optimal routing because of internal EIGRP's lower cost than
ISIS,
and ISIS's lower cost than external EIGRP. However by leaving the
feedback
routes in the routing table of C and D you risk temporary routing loops
if
networks dissappear in the EIGRP network. Say the ethernet on router A
goes
down, router A will query its EIGRP neigbors for another route to that
ethernet. D will report that it has a route from F, and C will also
report
an available route from E. A will then place two new routes in its table
for
an ethernet that is quite obviously down. This loop will clear up
because
ISIS will eventually discover the loss of the original route, but the
table
at A will look pretty funny for a while.
----- Original Message -----
From: "Jorge Epifbnio" <jorge.epifanio@contacto5.icep.pt>
To: <ccielab@groupstudy.com>
Sent: Saturday, December 28, 2002 3:28 PM
Subject: Redistribution EIGRP/ISIS
> When redistributing EIGRP/ISIS (on routers C and D) is it really
> necessary to prevent loops and route feedback?
>
> An EIGRP route on a border router will have AD=90 and AD=115 (feedback
> from EIGRP route) so it will always choose the internal path through
the
> EIGRP domain.
>
> An ISIS route on a border router will have AD=115 and AD=170 (feedback
> from ISIS route) so it will always choose the internal path through
the
> ISIS domain.
>
>
>
>
>
> A---B
>
> | |
>
> C D
>
> | |
>
> E---F
>
>
>
> (Doyle page 799 Exercise 5)
> .
.
.
This archive was generated by hypermail 2.1.4 : Fri Jan 17 2003 - 17:21:54 GMT-3