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Re: It's Ars Tech's turn to bang the IPv4 exhaustion drum
On 19 aug 2008, at 22:29, Kevin Loch wrote:
I thought there was an issue with duplicate address detection with / 127
Don't know about that, but the all-zeroes address is supposed to be the all-routers anycast address. Cisco doesn't implement this, so /127 works on those, but there are some other vendors that do, so /127 won't work on those boxes. (And wouldn't it be funny if Cisco decided to start implementing the all-routers anycast address...)
/126 should work and lots of folks use /112 which is a more human-friendly bit boundary. /112 is also good for multiple access vlans and just about anything that isn't using autoconfig.
I like using EUI-64 addressing, i.e.:
! interface vlan666 ipv6 address 2002:dead:beaf:666::/64 eui-64 !
This has the advantage that you don't have to explicitly assign an address to each router, it all works out automatically and you can copy/paste configs from one box to the other.
I also like to put the VLAN ID in bits 48 - 63. This makes the IPv6 addressing plan REALLY simple...