nanog mailing list archives
Re: IPv6 prefixes longer then /64: are they possible in DOCSIS networks?
From: Steven Bellovin <smb () cs columbia edu>
Date: Mon, 28 Nov 2011 17:00:14 -0500
On Nov 28, 2011, at 4:51 52PM, Owen DeLong wrote:
On Nov 28, 2011, at 7:29 AM, Ray Soucy wrote:It's a good practice to reserve a 64-bit prefix for each network. That's a good general rule. For point to point or link networks you can use something as small as a 126-bit prefix (we do).Technically, absent buggy {firm,soft}ware, you can use a /127. There's no actual benefit to doing anything longer than a /64 unless you have buggy *ware (ping pong attacks only work against buggy *ware), and there can be some advantages to choosing addresses other than ::1 and ::2 in some cases. If you're letting outside packets target your point-to-point links, you have bigger problems than neighbor table attacks. If not, then the neighbor table attack is a bit of a red-herring.
The context is DOCSIS, i.e., primarily residential cable modem users, and the cable company ISPs do not want to spend time on customer care and hand-holding. How are most v6 machines configured by default? That is, what did Microsoft do for Windows Vista and Windows 7? If they're set for stateless autoconfig, I strongly suspect that most ISPs will want to stick with that and hand out /64s to each network. (That's apart from the larger question of why they should want to do anything else...) --Steve Bellovin, https://www.cs.columbia.edu/~smb
Current thread:
- IPv6 prefixes longer then /64: are they possible in DOCSIS networks? Dmitry Cherkasov (Nov 28)
- Re: IPv6 prefixes longer then /64: are they possible in DOCSIS networks? Ray Soucy (Nov 28)
- Re: IPv6 prefixes longer then /64: are they possible in DOCSIS networks? Owen DeLong (Nov 28)
- Re: IPv6 prefixes longer then /64: are they possible in DOCSIS networks? Steven Bellovin (Nov 28)
- Re: IPv6 prefixes longer then /64: are they possible in DOCSIS networks? Brzozowski, John (Nov 28)
- Re: IPv6 prefixes longer then /64: are they possible in DOCSIS networks? Fred Baker (Nov 28)
- Re: IPv6 prefixes longer then /64: are they possible in DOCSIS networks? Brzozowski, John (Nov 28)
- RE: IPv6 prefixes longer then /64: are they possible in DOCSIS networks? McCall, Gabriel (Nov 29)
- RE: IPv6 prefixes longer then /64: are they possible in DOCSIS networks? Nathan Eisenberg (Nov 29)
- Re: IPv6 prefixes longer then /64: are they possible in DOCSIS networks? Ray Soucy (Nov 29)
- Re: IPv6 prefixes longer then /64: are they possible in DOCSIS networks? Owen DeLong (Nov 29)
- Re: IPv6 prefixes longer then /64: are they possible in DOCSIS networks? Joel jaeggli (Nov 29)
- Re: IPv6 prefixes longer then /64: are they possible in DOCSIS networks? Owen DeLong (Nov 29)
- Re: IPv6 prefixes longer then /64: are they possible in DOCSIS networks? Jimmy Hess (Nov 29)
- Re: IPv6 prefixes longer then /64: are they possible in DOCSIS networks? Owen DeLong (Nov 28)
- Re: IPv6 prefixes longer then /64: are they possible in DOCSIS networks? Ray Soucy (Nov 28)