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Beginner

CISCO 3900 L (local route) Eliminates the multicast PHANTOM RP

hi

as far as i know, the routing decision is made:

1. longest match.

2. lower admin distance.

3. lower metric.

thus, if the router lerning /24 route (which is local, i.e loopback) and  /32  same route (by eigrp)

the router will prefer the /32 eigrp route.

but from my experience, i found that the local /24 route (whice mark in the routing table as L) is prefer over the learend eigrp /32 route.

is this a natural proccess?

is this a natural proccess when we talked about local inteface vs dynamic protocol?

thanks

jacob

CCIE#36456
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Advisor

CISCO 3900 LONGEST MATCH PROBLEM

Hi,

the Local route is always a host route so /32 and so AD comes into play and AD of connected is 0 which is lower than EIGRP( 90 or 170).

Regards.

Alain

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Beginner

Re: CISCO 3900 LONGEST MATCH PROBLEM

thanks for the quick responding.

it seems like it is true.

however this may caus a problem by using the multicat bidir Phantom RP which relies on the

longest match with loopbacks.

"The  preferred  method  for providing  Bidir  rendezvous  point redundancy  can  be   designed  using 

loopback networks with  different mask  length . This  mechanism  relies  on  unicast  routing  longest

match  route  lookups to guaranteea  consistent  path  to  the  rendezvous  point"

the Local routes is negeting the Phantom RP sulotion for redudencey RP.

any idea?

CCIE#36456
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