Subject: Re: Peculiar ICMP6 redirect rejection
To: der Mouse <mouse@Rodents.Montreal.QC.CA>
From: William Waites <>
List: tech-net
Date: 08/19/2002 13:10:01
>>>>> "derMouse" == der Mouse <mouse@Rodents.Montreal.QC.CA> writes:

    derMouse> ICMP6     redirect     rejected;     not    equal     to
    derMouse> gw-for-src=fe80:0001::02a0:24ff:fe66:fb23    (must    be
    derMouse> same):                (src=fe80:0001::0210:5aff:fefc:5c1a
    derMouse> dst=2001:0700:0400:0150::0001:0001
    derMouse> tgt=fe80:0001::02a0:24ff:fe66:fb23)

    derMouse> The address in the gw-for-src  and tgt= fields is the LL
    derMouse> address of the "portable"  machine.  The src= address is
    derMouse> the LL address  of the gateway to the  rest of the world
    derMouse> and the dst=  address is the address I'm  trying to make
    derMouse> portable.  (1 is the correct scope ID on that machine.)

That  looks prima  facie like  a  bug --  why is  this redirect  being
rejected? The only non LL address is  the one that is not on the local
subnet so  who cares about  the mask at  that point, standard  or not?
Unless the neighbour is trying to  use its LL address as the source IP
for its packets or some  such... Maybe a  tcpdump would give  a better
idea  of what's actually going on... 

    >> Standard subnet size is /64.  Wasteful of bits?  Maybe.

    derMouse> Very.   It means  that  at one  stroke, whatever  genius
    derMouse> decided on that has just  negated much of the benefit of
    derMouse> IPv6

I tend to agree but...