Re: route for linx.net in Level3?

[Tom Paseka <tom () cloudflare com>]

On Thu, Apr 4, 2013 at 1:43 PM, Randy Bush <randy () psg com> wrote:
> > > Even if the exchange does not advertise the exchange LAN, it's
> > > probably the case that it is in the IGP (or at least IBGP) of
> > > everyone connected to it,
>
> yikes!  this is quite ill-advised and i don't know anyone who does
> this, but i think all my competitors should.

Its more common than uncommon.

At WIX (Wellington), 64 out of 93 members will carry packets destined
to APE (Auckland Exchange).  (source:
http://conference.apnic.net/__data/assets/pdf_file/0018/50706/apnic34-mike-jager-securing-ixp-connectivity_1346119861.pdf)
 and this is just New Zealand!

Just checked a few exchanges, not just are the IXP ranges being
carried, they're being leaked:

Equinix SG:

$ bgpctl show rib 202.79.197.0/24
flags: * = Valid, > = Selected, I = via IBGP, A = Announced
origin: i = IGP, e = EGP, ? = Incomplete

flags destination          gateway          lpref   med aspath origin
      202.79.197.0/24              100     0 13335 23947 23947 ?
      202.79.197.0/24              100     0 13335 10026 i

Any2 LA:

bgpctl show rib 206.223.143.0/24
flags: * = Valid, > = Selected, I = via IBGP, A = Announced
origin: i = IGP, e = EGP, ? = Incomplete

flags destination          gateway          lpref   med aspath origin
      206.223.143.0/24             100     0 13335 9304 i
      206.223.143.0/24             100     0 13335 9304 i
      206.223.143.0/24             100     0 13335 4635 9304 i
      206.223.143.0/24             100     0 13335 9304 i


> > I have experience of several networks where that is not the case. IGP
> > carries routes for loopback and internal-facing interfaces;
>
> i have seen some carry external because, for some reason, they do not
> want to re-write next-hop at the border.
>
> randy