Re: mapping to the local-link address

Hello Mustafa!

I would like you to think about what the destination of the IPv6 packet is and whether or not there is the appropriate frame mapping in place for this address to be resolved. To check your logic, be sure to use the valuable command debug frame-relay packet after your ping attempt. This command will clearly tell you whether or not the ping is failing based on a lack of a frame mapping.

For example, if you are on a router directly connected to another over Frame Relay and you ping using the global unicast address (that you have mapped), it is going to work just fine. That is considering the other side is also configured properly.

But when a router receives a packet destined for a remote network and the local device must do a routing table lookup against a dynamic protocol, it will recurse and see a next-hop address as the link-local address of the neighbor and use this as the destination address. In this case, a mapping must be in place for the link local address or the ping will fail.

I highly suggest you lab this one up and play with it in order to know it absolutely cold before you consider a lab attempt.

One more note - vendor materials might not consistently present this in their solutions....for example, they might show a link local mapping when it is not actually required as they are just doing it out of habit.

Warmest Regards,

Anthony J. Sequeira, CCIE #15626
http://www.INE.com

Core Knowledge Rocks!
Q: What is the difference between the BGP commands always-compare-med and deterministic-med?
A: The bgp deterministic-med command forces the comparison of the MED variable when choosing routes advertised by different peers in the same AS. Bgp always-compare-med ensures the comparison of the MED for paths from neighbors in different ASes.
More Info: http://www.ciscosystems.com/en/US/tech/tk365/technologies_tech_note09186a0080094925.shtml

On Apr 26, 2010, at 12:52 PM, Mustafa Yadav wrote:

> hi guys,
> In some examples in frame realy&ipv6 there is a mapping for link local
> address but in some there will not .
>
> can someone tell me why is this?
>
>
> Blogs and organic groups at http://www.ccie.net
>
> _______________________________________________________________________
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html

Blogs and organic groups at http://www.ccie.net
Received on Mon Apr 26 2010 - 13:28:34 ART