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New Member

question regrading rip and eigrp

hi all

if a network is running both rip and eigrp , if on eigrp "auto summarisation is there" . if router on that network get 2 routes from both rip and eigrp "rip

got = 150.24.5.0 " and eigrp get = 150.24.5.0 "

case : 1

if rip was configured its admin distance as 90 " and eigrp is also admin distance 90 which route will it choose

case =2

if rip admin distance is 120 and eigrp admin distance is 90

case : 3

if i make eigrp "no auto summary "

then via rip that router get "150.24.0.0" and via eigrp that will get "150.24.5.0"

and apply the same above case 1 and case 2 for the above scenario which route a router will choose .

thanks

3 REPLIES
Hall of Fame Super Silver

Re: question regrading rip and eigrp

Case 1: both RIP and EIGRP advertise the same prefix 150.24.5.0 (I assume /24 - if not it may make a difference) and both are configured with the same administrative distance then IOS will choose one of the routes to put into the routing table. I tested this a long time ago and remember that the RIP route was chosen. There was a posting from a Cisco engineer in NetPro a little while back that says that the current behavior is that when there is a tie in administrative distance, that IOS will consider the default administrative distance to break the tie and so EIGRP would be chosen and put into the routing table.

case 2: both RIP and EIGRP advertise the same prefix 150.24.5.0 (I assume /24 - if not it may make a difference) and RIP has distance of 120 while EIGRP has distance of 90. In this case the EIGRP route is chosen and put into the routing table.

case 3: RIP advertises 150.24.0.0 (I assume /16) and EIGRP advertises 150.24.5.0 (I assume /24). In this case it does not matter what the administrative distance is because there are 2 different prefixes and both of them will be put into the routing table. The EIGRP route will be used for any addresses within 150.24.5.0/24 and RIP route will be used for all other addresses within 150.24.0.0/16.

HTH

Rick

New Member

Re: question regrading rip and eigrp

hi rick

thanks for your reply

in case 3 if both rip and eigrp has admin distance 90 and if rip advirtizes 150.24.0.0/16 and eigrp adverstizes 150.24.5.0/24 then which one will be taken. will both router appear in the routing table?

Hall of Fame Super Silver

Re: question regrading rip and eigrp

In my previous answer I said clearly that in case 3 both routes are put into the routing table.

HTH

Rick

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