From: Devender Singh (devender.singh@xxxxxxxxxxxxxx)
Date: Tue May 22 2001 - 20:02:03 GMT-3
Hai Mohammad,
Sorry to come the subject a bit late.
I agree this is Scary and I agree with what ever you said. What if this
situation
arises in the lab :-(((. I wish to discuss this bit futher.
This my understanding:
Normally summary-address used create a summary from type 5 LSA on ASBR (Say
rip to ospf ). But what happens when we use it to summarise the other way
around. When we redistribute ospf into say RIP, by rules it will get
redistributed into RIP, but if the mask on the outgoing RIP interface does
not match routes will not be progated into rip. The mask on the outgoing
interface does not have anything to do with basic process of redistribution.
Now if we redistribute RIP back into ospf without any route-map or
distribute-lists all this route will be inserted back into ospf but they
will not bother ospf because internal routes have preference over external
routes. Now the summary command ( our hack) does its job and pushes it back
to RIP with the mask we want also into ospf domain as external. Rest
everything is normal.
Does this make sense to you.
Best regards
Devender Singh
BE(Hons), CCNP
IP Solution Specialist
-----Original Message-----
From: Mohamed Heeba [mailto:MAHeeba@itqan.co.ae]
Sent: Saturday, 12 May 2001 9:04
To: 'ccielab@groupstudy.com'
Subject: OSPF summary and redistribution
guys ;
i have reached a conculation about the problem of the OSPF and summarization
/redistribution and wanted to share it with you who are interested .
i have revised Doyles chapter of redistribution ,there is an example of
redistributing RIP into IS-IS and at the end of this chapter ,(RIP is /24
and ISIS is /24 and /28 )
CLEARLY ,he NEVER use the command summary-address to summarize the ISIS
routes to the RIP and clearly also mentioned that ISIS /28 routes should be
summarized to RIP by using STATIC ROUTES !!!!.
so the point is the summary command should only be used to summarize
extrenal routes INTO ISIS or OSPF .but our problem is that we were trying to
go around this problem to avoid the use of static routes ,while in fact it
is an easy way to solve this problem.
going around the problem can may be done by a command like ip
default-network ,but this will require the major class network to be
different in both domains.
well...i guess in the real lab there should be way to avoid using the
summary address in opposite way and create more problems ....or they may
allow to use just single static route somewhere :))))))
hope someone can comment on this
Mohamed
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