APNIC IPv6 transit exchange

Bernhard Schmidt berni at birkenwald.de
Thu Dec 6 14:22:22 CET 2007

Hi Iljitsch,

> Although it's highly undesirable to have these overly long paths, I
> think it's important to point out that it takes two to tango: these
> paths wouldn't be visible in the routing tables if there were also short
> paths available. There are still people out there that have nice IPv6
> networks at home but refuse to play with the other kids in the peering
> playground.

There is a nice thing called localpref which is the major cause of such
AS path screwups if applied without decent filters.

For example this is causing GEANT2 (and thus the majority of european
NRENs) to follow paths like

csr1-2wr#sh bgp ipv6 unicast 2001:4830::/32
BGP routing table entry for 2001:4830::/32, version 263166
Paths: (3 available, best #1, table Global-IPv6-Table)
  680 20965 24490 24287 7660 9270 17832 1237 17579 3425 293 3257 30071
    2001:638:C:A003::1 from 2001:638:C:A003::1 (
      Origin IGP, localpref 90, valid, external
      Community: 680:77 7660:500 9270:17832 12816:2100 12816:2110
20965:24490 24489:7660 24489:65200

Yay! I have 85 of them this morning.


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