[ofa-general] [PATCH 1/4] ib/ipoib: specify TClass and FlowLabelwith PR queries for QoS support

[Eitan Zahavi]

Hi Jason, Sean,

Your mail triggered me to double check the IPoIB for the sentence
requiring the SL and rate to follow the 
MCG. I was sure I have seen this in the IETF IPoIB spec and that was the
reason for my comments. 
But I can't find it there.  

So I must admit your argument regarding having the SL and rate be
calculated by the 
PathRecord for the unicast traffic seems reasonable to me.

Eitan

> -----Original Message-----
> From: Jason Gunthorpe [mailto:jgunthorpe at obsidianresearch.com] 
> Sent: Tuesday, August 07, 2007 8:35 PM
> To: Eitan Zahavi
> Cc: Sean Hefty; OpenIB
> Subject: Re: [ofa-general] [PATCH 1/4] ib/ipoib: specify 
> TClass and FlowLabelwith PR queries for QoS support
> 
> On Tue, Aug 07, 2007 at 07:59:46PM +0300, Eitan Zahavi wrote:
> 
> > > Can you clarify why you think the SL and rate should be provided, 
> > > versus just the traffic class and flow label?
> 
> > The broadcast group of the IPoIB subnet should dictate the 
> parameters 
> > to be used for that subnet.
> 
> There is no reason a unicast IPoIB path should be restricted 
> to having the same SL as the broadcast group. That limits the 
> possible topologies that can be routed efficiently. Sean's 
> use of the tclass to derive the SL seems correct to me. 
> Except in unusual cases the SL should not be specified in a PR query.
> 
> Rate and MTU should probably be copied over. Not sure about 
> flowlabel though..
> 
> Jason
>