[155881] in North American Network Operators' Group
Re: Level 3 BGP Advertisements
daemon@ATHENA.MIT.EDU (Randy)
Wed Aug 29 15:49:56 2012
Date: Wed, 29 Aug 2012 12:49:24 -0700 (PDT)
From: Randy <randy_94108@yahoo.com>
To: nanog@nanog.org, nick@flhsi.com
In-Reply-To: <12eb921c$6a0de4a3$7efc90a$@flhsi.com>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
--- On Wed, 8/29/12, Nick Olsen <nick@flhsi.com> wrote:
> From: Nick Olsen <nick@flhsi.com>
> Subject: Level 3 BGP Advertisements
> To: nanog@nanog.org
> Date: Wednesday, August 29, 2012, 12:28 PM
> Greetings all.
>=20
> In practice, We've always advertised our space all the way
> down to /24's=20
> but also the aggregate block (the /20 or the /21). Just so
> there was still=20
> reachability to our network in the event that someone made
> the foolish=20
> mistake of filtering lets say prefixes smaller /23...
>=20
> Anyways, I've always thought that was standard practice. And
> its never been=20
> a problem. Until we brought up peering with level 3..
>=20
> I noticed that while the /24's made it out to the world. The
> larger=20
> counterparts (2 /21's and a /20) did not. So, I start
> sniffing around. Find=20
> that I do indeed see the prefixes in Level 3's looking glass
> but they=20
> aren't handing it off to peers. So, Naturally, I land on
> this being some=20
> kind of prefix filtering issue and open a ticket with Level
> 3. They tell me=20
> this is standard practice. And If I want to see the /20 or
> /21's make it=20
> out to the rest of the world, I need to stop sending the
> /24's.
>=20
> Does this sound normal?
> Is what I'm doing (Advertising the aggregate prefix) a good
> rule of thumb?
>=20
> Any other thoughts?
>=20
> Nick Olsen
> Network Operations (855) FLSPEED=A0 x106
>=20
> =20
my 2 cents: I would think L3 would announce the /20 and /21's and no-export=
the /24
Why announce more-specifics if you can get away with a few shorter-prefixes=
.
Do you have a setup where you have to announce /24's? If you can do with a =
/20 and two /21's, that would be the way to go.
./Randy
