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-j...) 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