On 11/28/11 10:29 AM, "Ray Soucy" <r...@maine.edu> 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). [jjmb] for point to point I agree with this point. If a /64 is reserved one has greater flexibility as far as what is configured on the interfaces. > >When it comes to implementation, though, it's not as simple as a yes >or no answer. > >The actual use of 64-bit prefixes is not something I would currently >recommend for large-scale deployments due to the denial of service >attack vector it opens up (neighbor table exhaustion). [jjmb] not sure I agree, this depends on where the prefix is being installed in the network. > >Not using 64-bit prefixes tosses SLAAC out the window; but for many >networks SLAAC may not be desirable anyway due to the lack of control >it presents. > >Once vendors come out with routers that are able to protect against >neighbor table exhaustion, moving to a 64-bit prefix (which you >hopefully reserved) will allow you to be more flexible in what >addressing methods are used. > >On Mon, Nov 28, 2011 at 6:37 AM, Dmitry Cherkasov <doctor...@gmail.com> >wrote: >> Hello everybody, >> >> It is commonly agreed that /64 is maximal length for LANs because if >> we use longer prefix we introduce conflict with stateless address >> autoconfiguration (SLAAC) based on EUI-64 spec. But SLAAC is not used >> in DOCSIS networks. So there seems to be no objections to use smaller >> networks per cable interfaces of CMTS. I was not able to find any >> recommendations anywhere including Cable Labs specs for using >> prefixes not greater then /64 in DOCSIS networks. Some tech from ISP >> assumed that DHCPv6 server may generate interface ID part of IPv6 >> address similarly to EUI-64 so MAC address of the device can easily be >> obtained from its IPv6 address, but this does not seem like convincing >> argument. What do you think? >> >> >> Dmitry Cherkasov >> >> > > > >-- >Ray Soucy > >Epic Communications Specialist > >Phone: +1 (207) 561-3526 > >Networkmaine, a Unit of the University of Maine System >http://www.networkmaine.net/ >
