13

In v4, most of the operators filter BGP updates for prefixes longer than a /24, to preserve the size of the full view.

What about IPv6 ? Is there such "convention" that stands out ?

Benjamin A.
  • 1,687
  • 2
  • 15
  • 27

1 Answers1

19

These days it's usually at /48, and it's very unlikely to ever be longer.

There are still AS' filtering longer than /32 though, but they should all have a default at this point (Verizon were a hold-out, but I believe they've given up).

There are also AS' filtering on allocation lengths, so if you got a /32 they might require you advertise it as such (based on the various RIR's documented allocation policies).

LapTop006
  • 1,743
  • 11
  • 24
  • 1
    Wow, filtering on allocation length ? That makes impossible for a content provider to serve geo-based prefixes, right ? – Benjamin A. May 18 '13 at 11:19
  • 1
    Not really, if they're disparate networks the RIR's allow multiple allocations in the correct space (at least ARIN, RIPE & APNIC do). There was a recent NANOG thread about this. – LapTop006 May 18 '13 at 11:22
  • 1
    I should really subscribe to NANOG then, even if I'm french ! – Benjamin A. May 18 '13 at 11:28
  • It's as close to a global NOG as it gets, although posting non-North American content usually gets complaints. – LapTop006 May 18 '13 at 11:35
  • @BenjaminA.: This has been discussed on FRnOG too. See http://www.mail-archive.com/frnog@frnog.org/msg22235.html – petrus May 19 '13 at 09:31