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

[Jason Gunthorpe]

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

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.)

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.

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

Regards,
Jason