[ewg] Re: [ofa-general] [PATCH 2/9] ib_core: kernel API for GID -->MAC translations

[Jason Gunthorpe]

On Wed, Jun 17, 2009 at 11:20:26AM -0700, Roland Dreier wrote:
> 
>  > Hum, This is a very tricky subject. Co-mingling the IB GID address
>  > space and the IPv6 address space like this is not really something
>  > that was envisioned from the IBA side.
> 
> Doesn't the IB spec say that an IB GID *is* an IPv6 address?  So in
> theory it should be OK; however I don't think in practice anyone paid
> attention to making sure that the IB GID space works as an IPv6 address.

It is like an IPv6 address but it was expressly envisioned to be a
seperate space. The IBA authors copied many of the conventions from
IPv6 for numbering this new space, like link local, and multicast
prefixes, but it was not intended to be co-mingled.

That said, because of the incredible similarity it could probably be
co-mingled, with some research and validation, but IIRC the main
reason this wasn't done from the start is that the IETF wasn't
interested in supplying a protocol number and the definition work to
make IB over IPv6 a standard. So instead we have IB over GRH, which is
99% the same....

So, I didn't look closely enough, but what was the ethertype that is
used here in this patch set? Hopefully not IPv6.

Therin is the oddness, if the main IPv6 routing table is used to
direct packets that are not labeled with the IPv6 ethertype that is
very confusing - on the other hand if the RDMA packets are labeled
with the IPv6 type then you need IETF to supply a protocol number for
this.

In either case, this is a good point, it is difficult to imagine
including this work in Linux until either IEEE or IETF supply a
number..

Jason