[c-nsp] IPV6

[Phil Mayers]

Michael Robson wrote:
> It's been a while since I worked with IPV6 and I am now once again
> plunging myself into this feckless world and was wondering if a
> couple of holes had now been plugged. What is the accepted way in
> IPV6 land to dish out IPV6 DNS server addresses (am I correct in
> saying that if you make use of NDP, you would still have to manually
> configure DNS servers)? The other hole, as was, is the lack of IPV6

There are 4 methods:

  * Don't use IPv6 DNS - use IPv4 DNS servers (via DHCPv4 or other). I 
believe this is pretty common

  * Static config of IPv6 DNS servers, possibly using an anycast address 
(I seem to recall there are products which try a well-known DNSv6 
address, but I can't remember what products, and what address)

  * Advertisment in RA packets - RFC 5006. I think support for this on 
IOS is pretty thin - I'm fairly sure 6500s don't support it and don't 
have it roadmapped (sigh)

  * DHCPv6

> help address functionality on Cisco routers (well 6500s at least): if
> I were to go down the route of using DHCP for IPV6, how could I use a
> central server without this helper functionality?

6500s running SXI have gained the DHCPv6 relay support. Sadly, it 
doesn't interoperate with 6vPE (which we use) so I've only tested it 
lightly, but it more or less worked.

Of course, many clients don't support DHCPv6 (e.g. WinXP) so you may 
still need a solution for those.