DLCTRACE interpretation

[mferrando]

I'm analyzing a DLCTRACE in a SNASW (EE on uplinks and DLSw for downstream PUs) environment. I see several entries labeled as SEND_MU frame but I cannot understand its format and meaning.

Here follows an example:

379397 IT0M In sz:68 SEND_MU

09:38:34.99, 15 December 2004

0000 00000000 00000000 663C7EB4 00020000 *..........=.....*

0010 00000000 00000000 00000000 00000000 *................*

0020 00000044 00000044 00000000 00000000 *................*

0030 05000000 00000044 500F0000 00000000 *........&.......*

0040 00020000 *.... *

I've seen in the troubleshooting document on SNASw (http://www.cisco.com/en/US/tech/tk331/tk336/technologies_white_paper09186a008011ff1b.shtml) some reference on SEND_MU's but I couldn't find an explanation or the packet layout.

can anybody tell me where I can find some additional information on these entries? Thanks

[rclousto]

This is an internal signal between DLC and path control, that tells path control to update its send credit to allow more MU's to be able to be sent down to the DLC. You won't find this documented anywhere in places like SNA Formats because it doesn't flow between nodes.

Except for the 4 bytes at offset 0x08, which is just a pointer, the data is all the same in every instance I've found, so I don't think there's any value in documenting it. I've never even paid attention to it myself, I just consider it overhead. We'd probably look at this if we suspected a problem with path control holding onto frames and not sending them out on the DLC.

Regards,

Bob