[c-nsp] Route Aggregation and Deaggregation

[Jennifer Pruett]

Thanks for the comments so far! I am too under the same logic; however, a
certain provider that provides traffic scrubbing (to remain anonymous) for
DoS attacks states that any prefixes that we announce to them for scrubbing
should be deaggregated from other providers so that no other providers
ultimately "blackhole" the traffic due to specific routing policies that
have been set forth internal to the providers network (i.e. Communities,
local pref, MEDs and such). It did not make much sense, as I understood it
as the longer prefix would be preferred. Additionally, I do not want to
send any additional noise to the global routing table by deaggregating,
there is too much of that now in my opinion. I am just not seeing the logic
of the statement that I should deaggregate. As long as others are in
consensus, then I am a happy camper.

Again, I thank you all for your input!

Jen

On Wed, Jul 18, 2012 at 8:05 PM, Sascha Pollok <nsp-list at pollok.net> wrote:

> Hi Jen,
>
> +1 for Tony. I would just like to make clear: please do NOT deaggregate
> the /19. You can advertise a more-specific /24 to ISP3  OR  advertise
> the more-specific /24 to all three ISPs. But please do *not* deaggregate
> the /19 into 32x /24.
>
> Good luck
> Sascha
>
>
> On Wed, 18 Jul 2012, Tony wrote:
>
>  Hi Jen,
>>
>> You can do that. All of your traffic for the /24 will come to you via
>> ISP3 as this is a more specific match than the /19 it is part of. If you
>> drop your link to ISP3, then your /24 traffic will then be received via one
>> of the /19's you advertise to ISP1 & ISP2.
>>
>> If this is your intention, then go for it. No need to also advertise the
>> /24 to ISP1 & ISP2 unless you want some of the traffic for that /24 to come
>> inbound on those links.
>>
>>
>>
>> regards,
>> Tony.
>>
>>
>>
>>
>>  ______________________________**__
>>> From: Jennifer Pruett <jennypruett88 at gmail.com>
>>> To: cisco-nsp at puck.nether.net
>>> Sent: Thursday, 19 July 2012 3:28 PM
>>> Subject: [c-nsp] Route Aggregation and Deaggregation
>>>
>>> Good day!
>>>
>>> Question for any BGP guru's; we have a couple of ASR routers as our
>>> border
>>> routers which are advertising a few /19's. The question is not directly
>>> related to the ASR hardware, but the
>>> process and best practice of aggregating PI assigned space. If we
>>> advertise
>>> our /19's via ISP1 and ISP2 and then introduce ISP3 and only advertise a
>>> /24 from one
>>> of the /19's, do we have to deaggregate the /19 that the /24 was pulled
>>> out
>>> of to accommodate the /24 that we would advertise via ISP3? What are the
>>> ramifications of
>>> such actions?
>>>
>>> Thanks for your time
>>> Jen
>>>
>>