On 2/23/2017 3:55 PM, Jason Gunthorpe wrote:
On Thu, Feb 23, 2017 at 03:33:53PM -0500, Tom Talpey wrote:
The key words are "IETF-approved". Mitigation and Interaction are
operational decisions, not protocol design.
We are talking about this bit from RFC 3530 ?
Where an NFS version 4 implementation supports operation over the IP
network protocol, the supported transports between NFS and IP MUST be
among the IETF-approved congestion control transport protocols, which
include TCP and SCTP.
This gives most of RDMA an out as it is not over the IP protocol. The
only obvious troubled one is RoCEv2..
RFC7530 has updated this text somewhat, but it's similar, yes.
https://tools.ietf.org/html/rfc7530#section-3.1
The specification language specifically calls out IP-based transports,
which is why I mentioned that RoCEv1, being non-IP-based and not even
truly routable, could obtain a bye. But the NFS layer IMO should really
not be digging down to this level. I think it would be much better if
each transport could expose a relevant attribute, which NFS could
optionally inspect.
As you mention, RoCEv2 is a bit of a pickle. It's UDP/IP-based, and it
does have end-to-end congestion control, but technically speaking it
is not "IETF approved". I'm not sure what call to make there.
Tom.
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