[184385] in North American Network Operators' Group
Re: /27 the new /24
daemon@ATHENA.MIT.EDU (Michael Still)
Fri Oct 2 13:12:59 2015
X-Original-To: nanog@nanog.org
In-Reply-To: <CAGbD49od0awSEbLU_sPWgZZatLOszY500RPPkDqB=bZKD5bd_g@mail.gmail.com>
Date: Fri, 2 Oct 2015 13:08:16 -0400
From: Michael Still <stillwaxin@gmail.com>
To: Jason Baugher <jason@thebaughers.com>
Cc: NANOG <nanog@nanog.org>
Errors-To: nanog-bounces@nanog.org
There are lots of transits that will take le 32 on their customers inbound
but filter le 24 on egress announcements.
On Fri, Oct 2, 2015 at 12:47 PM, Jason Baugher <jason@thebaughers.com>
wrote:
> Are you suggesting that the Tier 1 and 2's that I connect to are not
> filtering out anything shorter than /24? My expectation is that they are
> dropping shorter than /24, just like I am.
>
> Correct me if I'm wrong, but every *NOG BGP best practices document I've
> read has advocated dropping all prefixes shorter than /24 at ingress and
> egress.
>
> On Fri, Oct 2, 2015 at 11:34 AM, William Herrin <bill@herrin.us> wrote:
>
> > On Fri, Oct 2, 2015 at 11:55 AM, Suresh Ramasubramanian
> > <ops.lists@gmail.com> wrote:
> > > Besides which more than one provider filters by a minimum prefix length
> > > per /8 - wasn't Swisscom or someone similar doing that? So multi
> > > homing with even a /24 is somewhat patchy in terms of effectiveness
> >
> > Hi Suresh,
> >
> > That hasn't been true for something like a decade. Anybody who filters
> > anything shorter than /24 without also taking a default route (or the
> > equivalent) is not fully connected to the Internet.
> >
> > Regards,
> > Bill Herrin
> >
> >
> >
> > --
> > William Herrin ................ herrin@dirtside.com bill@herrin.us
> > Owner, Dirtside Systems ......... Web: <http://www.dirtside.com/>
> >
>
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