Avoiding out of order large (greater than MTU) UDP datagrams with nxge (Doc ID 1513884.1)

Last updated on OCTOBER 02, 2015

Applies to:

Solaris SPARC Operating System - Version 10 3/05 and later
Information in this document applies to any platform.
***Checked for relevance on 01-Jun-2014***

Symptoms

 When using nxge interfaces to handle UDP traffic with datagrams which must be fragmented and reassembled (datagram larger than the interface MTU), it is possible that UDP datagrams may be delivered slightly out of order vs. the order at which they arrived at the interface.

The UDP protocol has no guarantees about the order at which individual datagrams may arrive - a slight variance in the order of datagram arrivals is therefore technically not really an issue, per the protocol. 

That said, in practice, it has been found that some applications will not handle even a small amount of datagram reordering.   Symptoms observed have been increased latency (the application may request re-transmission of some datagrams), and/or poor throughput.

Cause

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