ICSW - MPLS

Unanswered Question
Feb 28th, 2007

Hi I'm studying for the Secure Converged networks exam, I have a question about how LSR's handle summarised routes.

ie.A packet from network 10.10.10.0/24 arrives at the LSR, the LSR is then configured to summarise to 10.0.0.0/8 will there be LFIB entries for both networks and will any networks be dropped.

I have this problem too.
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swmorris Thu, 03/01/2007 - 04:34

Routing on an LSR works pretty much like it does in a general routing scenario.

If the 10.0.0.0/8 is the only entry that you have available, then that's the path it will match and take.

If you are an LSR, we have two options. Either a packet arrives without a label (in which case, routing takes place which may lead to an LSP) or it arrives with a label (in which case the LFIB is consulted popping one label and replacing with another (based on the label, not the route).

If the label is destined to be popped off and processed locally it's just like the first scenario where the routing table is consulted.

HTH,

Scott

[email protected]

beschbach Thu, 03/01/2007 - 11:52

What books are you using for this exam because I am still waiting for the new self study guide to come from Cisco Press? Any info would be greatly appreciated. Thanks!

jarlaw2812 Thu, 03/01/2007 - 12:31

If you have access to the Cisco Partner E-Learning connection web page, there is a web based training for the ISCW test.

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