nanog mailing list archives
Re: IPv6 prefixes longer then /64: are they possible in DOCSIS networks?
From: "Brzozowski, John" <John_Brzozowski () Cable Comcast com>
Date: Wed, 30 Nov 2011 16:56:58 +0000
Technically this is not true. SLAAC is not prohibited, it does come with side affects that complicate the deployment of IPv6. It is technically feasible to use SLAAC, it is just not practical in most cases. Stateful DHCPv6 is the preferred mechanism for address and configuration assignment. Prefix delegation requires the use of stateful DHCPv6 in DOCSIS networks. John ========================================= John Jason Brzozowski Comcast Cable e) mailto:john_brzozowski () cable comcast com o) 609-377-6594 m) 484-962-0060 w) http://www.comcast6.net ========================================= On 11/29/11 7:09 AM, "Dmitry Cherkasov" <doctorchd () gmail com> wrote:
Steven, SLAAC is prohibited for using in DOCSIS networks, router advertisements that allow SLAAC must be ignored by end-devices, therefore DHCPv6 is the only way of configuring (if not talking about statical assignment). I have seen at least Windows7 handling this properly in its default configuration: it starts DHCPv6 negotiation instead of auto-configuration. Dmitry Cherkasov 2011/11/29 Steven Bellovin <smb () cs columbia edu>: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:
- Re: IPv6 prefixes longer then /64: are they possible in DOCSIS networks?, (continued)
- Re: IPv6 prefixes longer then /64: are they possible in DOCSIS networks? Bill Stewart (Nov 30)
- Re: IPv6 prefixes longer then /64: are they possible in DOCSIS networks? Mark Blackman (Nov 30)
- Re: IPv6 prefixes longer then /64: are they possible in DOCSIS networks? Ray Soucy (Nov 30)
- Re: IPv6 prefixes longer then /64: are they possible in DOCSIS networks? Valdis . Kletnieks (Nov 30)
- Re: IPv6 prefixes longer then /64: are they possible in DOCSIS networks? Leo Bicknell (Nov 30)
- Re: IPv6 prefixes longer then /64: are they possible in DOCSIS networks? Jimmy Hess (Nov 30)
- Re: IPv6 prefixes longer then /64: are they possible in DOCSIS networks? Jimmy Hess (Nov 30)
- Re: IPv6 prefixes longer then /64: are they possible in DOCSIS networks? Leo Bicknell (Nov 30)
- 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? Dmitry Cherkasov (Nov 29)
- Re: IPv6 prefixes longer then /64: are they possible in DOCSIS networks? Brzozowski, John (Nov 30)
- 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? Leo Bicknell (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? Jeff Wheeler (Nov 28)
- Re: IPv6 prefixes longer then /64: are they possible in DOCSIS networks? Valdis . Kletnieks (Nov 28)
- Re: IPv6 prefixes longer then /64: are they possible in DOCSIS networks? Jonathan Lassoff (Nov 28)
- Re: IPv6 prefixes longer then /64: are they possible in DOCSIS networks? Dmitry Cherkasov (Nov 29)
- Re: IPv6 prefixes longer then /64: are they possible in DOCSIS networks? Jeff Wheeler (Nov 29)
- Re: IPv6 prefixes longer then /64: are they possible in DOCSIS networks? Valdis . Kletnieks (Nov 29)