[openib-general] Re: IB Address Translation service

[Hal Rosenstock]

On Wed, 2005-04-06 at 07:30, Michael S. Tsirkin wrote:
> > > Some DHCP servers (dhcpd) let you configure a fixed IP per hardware address.
> > > It seems to me that making this work requires an invariant QP, right?
> > 
> > I believe that DHCP servers require work in order to do this for IPoIB
> > as they do not understand an IPoIB hardware address.
> 
> Are we talking about IPoIB hardware address size issues?

I was referring to dealing with IPoIB DHCP zero'ing chaddr field wuth
hlen 0 and indicating htype of IPoIB. Not sure whether this is supported
without any changes to DHCP servers. The other issue would be the
support for the client identifier field and whether this is supported or
needs work.

> So a client could, for example, mask the QP number and use the
> remaining non-volatile portion as the identifier?

(This is what I said in a previous email in terms of making this work 
for RARP). That works if this is unique in the IP subnet. That's not
true in all cases. Also, per the emerging DHCP requirement, it does not
follow the format for the client identifier as an IAID is also required.
I suppose if there is only 1 interface then IAID isn't a problem either.

> Do you know whether dhcp clients / servers support this?

Not sure exactly which this you are referring to. The I-D requirement
(RFC3315id) is likely not supported.

> dhcpd man page seems to talk only about hardware address.

I think it may be dependent on which DHCP client/server. For the ISC
one, the changes were minimal (I put them out; there is one update
since) but this doesn't support 3315id.

-- Hal