[tsvwg] RDMA Support by UDP FRAG Option

["C. M. Heard" <[e-mail]>]

On Thu, Jun 10, 2021 at 9:43 PM Joseph Touch wrote:

> - do we want/need RDMA support?
>         if not, we ditch the frag length in non-terminal frags
>


I am going to reveal my ignorance by asking what is meant by RDMA (Remote
Direct Memory Access). But I'm fine with that as long as we end up with an
unambiguous problem statement.

The specification that I found with a Google search is "InfiniBand™
Architecture Specification Release 1.2.1 Annex A17: RoCEv2," available at
https://cw.infinibandta.org/document/dl/7781/.

This is a datacenter protocol and requires very specific conditions in
order to work, not the least of which is that it assumes that the IP/UDP
layer is nearly lossless and free from reordering.

This protocol handles its own data placement and integrity checks -- indeed
it requires UDP CS=0 to avoid redundant work -- and AFAICT would not in any
way benefit from UDP options.

If you have something else in mind, please let us know what it is.
Otherwise, I'd say that UDP options does not need to make any effort to
support RDMA.

Mike Heard