[ofa-general] Re: OpenSM IPv6 consolidation

[Ira Weiny]

On Thu, 29 May 2008 12:27:12 -0700
Hal Rosenstock <hrosenstock at xsigo.com> wrote:

> Ira,
> 
> In osm_sa_mcmember_record.c:__search_mgrp_by_mgid, there is:
> 
> #define PREFIX_MASK (0xff12601b00000000ULL)
> 
> Shouldn't all scopes be consolidated so this should be:
> 
> #define PREFIX_MASK (0xff10601b00000000ULL)
> 
> or was this intentional for some reason ?
> 

It seemed reasonable for this to consolidate link-local only because according
to my IPv6 book, solicited node multicast is the particular range,
ff02::1:ff00:0/104

However, I am a bit confused about how the scope bits map from the IP address
to the MGID.  The MGID refers only to the IB-subnet scope _not_ IP, therefore
what I said above might not matter because we are now talking about the IB
scope.

But that begs the question: Can a node issue an SNM request to a node in
another IB subnet?  (I think the answer is yes if the IP subnet spans more than
one IB subnet)  In that case, the SNM address would be in the range
ff02::1:ff00:0/104 but what MGID would that map onto in IB?  I think the
current mapping results in an IB link-local scope.  So would a router have to
forward it even though the IB scope is link-local?

Now my head hurts...  :-(

Ira