RE: whats the advantage of "nssa translate type7 suppress-fa "

Hi Vibs,

If you want to understand it properly you need to know some facts:

1- In many networks we prefer not to use real/big IP address ranges for our
links (like FR p2p etc.)
2- The IP addresses mentioned above are not necessarily advertised into the
entire network (so are not globally reachable)
3- In NSSA you may or may not wish to advertise all the IP ranges associated
with your internal links into your backbone area (see 2).
4- If you have some massive NSSA areas (a common practice in some networks)
you'll end up with many small IP ranges that you probably you dont want to
send them into your backbone area.
5- In NSSA configuration your ABRs act as 7->5 translators.
6- As a part of a LSA type 5 advertisement, generated by your ABRs, you have a
field called "Forward address" which by default points to your ASBR(s) (the
actual importers of your external prefixes).

Now my question is; what if you wish to filter out all IP ranges associated
with your links to reduce your LSDB in your backbone area? (or any other
design constraint)

Well, the Forward address field (effectively sort of next hop for your
external routes) is no longer available! because your backbone routers (except
the ABR connected to your NSSA) have no idea how to get to them while the FA
is not reachable.

How to fix it up?

Easy. Use the "translate type7 suppress-fa" command. It replaces the actual
value of the forward address fields with 0.0.0.0 . It makes your backbone
routers get a hold of the ABR (the actual 7->5 translator) to get to external
addresses advertised from your NSSA area.

- If you need a real world scenario, pls let me know.

HTH,

Regards,
Kambiz Agahian
CCIE Instructor, CCIE,CCSI,CCNP,WAASSE,MCSE,MCSA,MCTS

Network Learning Inc

375 N. Stephanie Street Bldg. 21 Suite 2111

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-----Original Message-----
From: nobody_at_groupstudy.com on behalf of Vibeesh S
Sent: Sun 4/4/2010 12:29 AM
To: Cisco certification
Subject: whats the advantage of "nssa translate type7 suppress-fa "

Hi,

whats the advantage of "nssa translate type7 suppress-fa" & where/how is it
typically used in real deployments.

Thanks,
Vibs

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Received on Sun Apr 04 2010 - 01:08:22 ART