[ofa-general] [RFC] host stack IB-to-IB router support

[Diego Crupnicoff]

> -----Original Message-----
> From: general-bounces at lists.openfabrics.org [mailto:general-
> bounces at lists.openfabrics.org] On Behalf Of Jason Gunthorpe
> Sent: Wednesday, March 21, 2007 1:32 AM
> To: Yaron Haviv
> Cc: general at lists.openfabrics.org
> Subject: Re: [ofa-general] [RFC] host stack IB-to-IB router support
> 
> On Wed, Mar 21, 2007 at 04:21:15AM +0200, Yaron Haviv wrote:
> 
> > I believe a much simpler and more generalized solution would be to
> > imitate the behavior of IP routing rather than using the "remote sa"
> > concept
> 

I completely agree with Yaron.

> We talked about this at some length a while ago on this list. In
> short, we started with the position you outlined until it was
> discovered that the L2 address checking described by 9.6.1.5.1 C9-57
> makes it unworkable. This existing IB behavior is sufficiently
> un-IP-like that existing IP solutions do not work. (The parallel to
> ethernet would be if each TCP connection checked that the SMAC in
> incoming frames matched some pre-determined value.)

If C9-57 is a problem then that can be addressed by the IBTA. 
BTW, the IBTA is going to present on IB routers spec during the upcoming
OFA workshop in Sonoma. That should be a good opportunity for non-IBTA
members to raise their concerns and potentially find ways to become
involved in the router architecture specification process. 

> 
> Sean is working on one of the simpler solutions that considers the
> effects of C9-57, which is to allow the active side to control all 4
> path records that are involved.
> 
> Notice this is similar to how IB CM works within a subnet, where the 2
> required paths are selected by the active side and the passive side
> does no queries. This already is different than IP which would have
> the passive side doing ARP. Again this behavior in the spec is
> fundamentally required by the restriction in C9-57.

For the IB spec, the SM and SA are subnet local entities. The remote SA
concept is at odds with the spirit of the IB spec. I would say that
changing that is a much more significant departure from the spec than
dealing with C9-57 if necessary.

> 
> I agree with you that this is not a good place to be, but with current
> hardware I think we are stuck with it..

I do not think so (with my ib hw asic vendor hat on). 

> 
> Regards,
> Jason
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