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Re: route for linx.net in Level3?
From: Tom Paseka <tom () cloudflare com>
Date: Thu, 4 Apr 2013 15:11:24 -0700

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



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