From: Serhat Aslan (serhatworks@gmail.com)
Date: Tue Jun 26 2007 - 21:09:34 ART
Hi,
q1: beside the ip addres hierarchy, take the problem as hardware limitations
and design practice, the main objective is to load the minimal system
resources on the core system. When the router take any prefix generally it
have to store its information based tables, you can accept them as routing
tables/database table/etc. It have to use memory also cpu cycle for compile
them for the accepted routing operations. Any logical operations reduce this
system performance so the main goal is keep this load as min.
q2: yes, Summary-routes are generally policy based operations(manual), the
null0 helps you simplify the process and give you more control over the
summarization of routes. But any kind of wrong logical operation probably
trigger the black-hole routing or packet ping-pong.
Serhat Aslan
On 6/27/07, ccie2k4@gmail.com <ccie2k4@gmail.com> wrote:
>
> Hi group,
>
> Q1.
> Just want to confirm best practices for summarization in a real world
> scenario. Reading various docs and whitepapers it says that the
> summarization should occur on the distribution layer as per the guidelines
> however say you are using a range from the same subnet between your core
> and
> distribution would it still be ok to summarize at the distribution. For
> eg:
> say you have a range 10.10.10.0/24 and u are using loopback ip's (all
> /32's)
> on all your routers from this range (even on the core and distribution)
> than
> where would you summarize this network. Does it make sense than to
> summarize
> all the /32's from this range at the core into a /24 and advertise it out.
>
> Q2.
> Another question I am trying to figure out what could be the effect if
> this
> summary somehow found its way back into your environment through the
> redundant links which would definetly happen in this case. I don't think
> it
> should have any adverse effects since the other devices would only refer
> to
> this route if they do not have a more specific route and even than the
> worst
> would be that depending on the metric that it chooses (this summary route
> will be configured and advertised on multiple devices) for this route it
> would just drop it since the summary would be to null0. Does this make
> sense
> or am I missing something? Thx for your help.
>
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