Re: Route summarisation and discard route.

Hi Jacek,

1) With EIGRP, when you create the summary route, at the end of the
definition, you can set the admin distance of the discard route - if you
wish for the router not to have the discard route, just set the admin
distance to 255.

2) I'm not sure about this one, I'm guessing in part because of the classful
heritage of RIP, when you specify which networks to advertise into RIP, you
the configuration uses classful networks even if you have "no auto-summary"
and the prefixes being exchanged between neighbors are classless.

3) There is a potential risk of introducing routing loops if you provide
aggregation facilities and for instance have a default route pointing back
towards the source of the traffic, rather than waiting to the IP packet's
TTL to expire, a discard route is a good "trap"

Cheers,
Adam

On Tue, May 31, 2011 at 12:45 PM, Jacek <q.192.168.1.0_at_gmail.com> wrote:

> Hello experts,
> I have questions about route summarisation and I am wondering why it
> behaves
> differently in different routing protocols.
>
> In OSPF discard route is installed automatically and there is a command to
> remove it: "no discard-route internal" and "no discard-route external"
> In EIGRP discard route is installed automatically but there is no command
> to
> remove it.
> Question 1: Why OSPF provides way to remove discard route but not EIGRP. Is
> there a deep reason for that ?
>
> In RIPV2 discard route is not installed automatically.
> Question 2: Why there is no discard route in RIP ?
> Question 3: Should a discard route be installed manually in RIP ? I mean as
> a best practice, not in the Lab.
>
> Thanks,
>
>
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Received on Tue May 31 2011 - 13:05:25 ART