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ssuet
Posts: 101
Registered: ‎09-21-2010
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Accepted Solution

IS-IS protocol L1/L2

Hi Expert

 

As we all know L1/L2 send attached bit toward L1 n Level area for Interarea routing

Some time it can introduce sub optimal routing .Like if i want to reach destination X the path to X from L1/L2 is more than the my neighbour Level1 router

 

Isnt   lack feature in IS-IS  that we have to bear Suboptimal routing because only way we can go outside from our area through L1/L2 or is there any work around

 

 

Your help will be highly appreciated

 

Thanks

Trusted Expert
Kashif-rana
Posts: 417
Registered: ‎01-29-2008
0

Re: IS-IS protocol L1/L2

Hi Dear

 

By default the ISIS L1 area is total stub (no inter-area and external routes). L1 ISIS routers rely on default route from L1//L2 router (ASBR). Each L1 ISIS router installs the default route from the nearest L1/L2 router (ASBR). So it could cause the suboptimal routing for the inter-area or external routes. Which is expected behaviour.

 

You can just do the route leaking for inter-area and external routes from the ASBR if you want to avoid this suboptimal routing.

 

HTH

Kashif Rana
JNCIE-SEC, JNCIE-ENT, JNCIE-SP, JNCIS(FWV,SSL),JNCIA(IDP,AC,WX),BIG IP-F5-LTM, CCNP
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Trusted Expert
Kashif-rana
Posts: 417
Registered: ‎01-29-2008
0

Re: IS-IS protocol L1/L2

Sorry it was typo ..... I meant ABR not ASBR :smileyhappy:

Kashif Rana
JNCIE-SEC, JNCIE-ENT, JNCIE-SP, JNCIS(FWV,SSL),JNCIA(IDP,AC,WX),BIG IP-F5-LTM, CCNP
----------------------------------------------------------------------------------------------------------------------------------------

If this post was helpful, please mark this post as an "Accepted Solution".Kudos are always appreciated!
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