[openib-general] Some Initial RMPP Wire Observations

[Hal Rosenstock]

Hi Sean,

Here are some wire based observations so far on RMPP running between a
toy SA client (making some GetTable requests) and OpenSM with RMPP
enabled:

Short RMPP messages (less than 1 MAD's worth) have first bit set but not
also last in RMPPFlags.

Also, if the initial RMPP send had bad status, that status is maintained
in the RMPP response (ACK) by the receiver side (SA GetTable). Is this
getting "reflected" ? Should such a send be ACKed ? Also,
AttributeOffset is not being cleared in that ACK.

In a multisegment RMPP send, the middle segments have their PayLoad
lengths set to whatever the user initially set this to. While it should
be ignored by the receiver, it would be better if these were sent as 0.

In the last segment, it appears that the pad is not cleared. This again
shouldn't matter but I didn't dig out what the spec says here.

Is there a restriction on the message size ? Up to what size have you
tested this ? I don't seem to get an ACK back when I send with a
PayLoadLength of 0x6E0 but do get one with 0x370. Any idea if this is a
problem with the sending client or a problem in the RMPP receiver code ?

Thanks.

-- Hal