From: Edwards, Andrew M (andrew.m.edwards@boeing.com)
Date: Wed May 26 2004 - 15:31:04 GMT-3
Use the 'no discard-route <internal/external>' to get rid of the route
to the Null0
Internal option for "area x range ......."
External option for "summary-address ....."
-----Original Message-----
From: ccie2be [mailto:ccie2be@nyc.rr.com]
Sent: Wednesday, May 26, 2004 9:50 AM
To: David Hurtado; ccielab@groupstudy.com
Subject: Re: "discard-route" command
Hi David,
If I remember correctly, this command could come into play when you
configure a summary in ospf.
For example, suppose you configure summary route on an ABR with the area
x range command. By default, ospf installs in the route table a route
to the null0 interface for the summary. In other words, if this router
receives any packets with a destination address of the summary itself,
when the router does a route lookup in the route table, it will find the
route to the null0 interface and discard the packet.
This makes sense because how can router route packets to a network that
doesn't actually exist which is what a summary network is, right?
So, getting back to your question, the summary route ospf installs in
the route table pointing to null0 is a "discard route".
What's confusing, though, is that this command isn't normally used
because, by default, ospf creates a "discard route" when you configure a
summary route. But, what if you don't want ospf to create a discard
route? No problem, just issue the "no discard route" command.
Unfortunately, I don't remember why you would want to do that. My
memory is very limited, but, hopefully, someone with a better memory
than myself will jump in here to answer that question.
HTH
----- Original Message -----
From: "David Hurtado" <dei2viccie@hotmail.com>
To: <ccielab@groupstudy.com>
Sent: Wednesday, May 26, 2004 12:04 PM
Subject: "discard-route" command
> Hello everybody,
>
> I'm trying to understand the function of the command: "discard-route".
> I have read the command explantion on DocCD several times and i have
> looked for an example in cisco.com, but i have not found any didactic
explanation.
>
> Would you mind to tell me where i can get a good example or
> explanation of the use of this command?
>
> Thanks a lot
>
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