From: Voytek Mielczarek (Voytek.Mielczarek@xxxxxxxxxx)
Date: Fri Aug 24 2001 - 07:36:26 GMT-3
Eric,
What options do we have with 12.1T and above for that scenario below?
Voytek
-----Original Message-----
From: Erick B. [mailto:erickbe@yahoo.com]
Sent: Friday, 24 August 2001 3:16 PM
To: 'ccielab@groupstudy.com'
Subject: Re: VLSM - FLSM procedure - One last time
Folks,
I know several people have discussed this here in past
and passed this off as a hack, etc and it working in
some versions and not others. Well, heres the scoop on
how the OSPF summary-address changed with 12.1T and
above.
Scenario:
You have an ASBR with a /30 point to point serial
interface and classfull network on another interface.
OSPF is active on the /30 interface. You need to
summarize the /30 network. You decide to use
redistribution and the OSPF summary-address method.
With 12.1, 12.0, and 12.0T and earlier you
redistribute into OSPF. The /30 interface is already
part of OSPF and redistribution puts this same
interface into OSPF as an external route and the
summary route is created. Going by current
documentation this is valid and expected. You have a
external route coming into OSPF so OSPF creates a
summary-address since the route matches. No hacks, no
funky behavior.
With 12.1T and above, you redistribute into OSPF. The
/30 interface is already part of OSPF and the
redistribution doesn't put the same interface into
OSPF thus the summary isn't created. So, the new rule
is with 12.1T and higher if the interface is part of
OSPF you can't redistribute that interface back into
OSPF.
Have fun!
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