Tony, I thought about that too, but I did not see the logic as the /24 that would be advertised would be based on the destination IP and potentially could be any of the 32 /24's at any give point in time.
Again, Thanks! Jen On Wed, Jul 18, 2012 at 9:49 PM, Tony <[email protected]> wrote: > I would hope that IF ($deity forbid) you needed to pull a single /24 out > of a /19 then it would be done in a way to create the smallest number of > resulting prefixes, eg: > > /19 = /20 + /21 + /22 + 2x /24 > > Which would result in "only" 4 extra prefixes being announced than a > single /19. > > > regards, > Tony. > > ------------------------------ > *From:* Sascha Pollok <[email protected]> > *To:* Tony <[email protected]> > *Cc:* Jennifer Pruett <[email protected]>; " > [email protected]" <[email protected]> > *Sent:* Thursday, 19 July 2012 4:05 PM > *Subject:* Re: [c-nsp] Route Aggregation and Deaggregation > > 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 <[email protected]> > >> To: [email protected] > >> 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 > > > _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
