using "reserved" IPv6 space
owen at delong.com
Tue Jul 17 06:44:42 UTC 2012
On Jul 16, 2012, at 11:16 PM, Jimmy Hess wrote:
> On 7/17/12, Karl Auer <kauer at biplane.com.au> wrote:
>> I'm not sure I follow the logic there. If the anycast router changes the
>> packet will be resent to the new subnet anycast router eventually
>> (assuming some layer cares enough about the packet to resend it). The
>> "last known hardware address" doesn't matter any more or less in this
>> scenario than it does in any other routing situation.
> The pertinent discussion is not about "any other routing situation";
> it's about first hop redundancy.
> The "last known hardware address" is in the NDP table, so the packet
> retransmissions likely wind up in the same place
NUD should actually take care of that.
> Another problem is the subnet anycast address may find unwanted
> routers that have to listen on it, including routers with only one
> interface and incomplete routing info, and including some
> unauthorized 5-port IPv6 router someone smuggled into the
> building and plugged in somewhere.
> By contrast, a real FHRP that implements failover either uses a
> virtual hardware address, or a 'gratuitous arp' type mechanism, so
> the packet retransmissions will go to the live failover partner.
The whole concept of gratuitous arp is strictly IPv4.
More information about the NANOG