Outbound Discards -- Definition?

[Darren Besler]

Can someone explain precisely what an outbound discard is? And what are the conditions by which they occur?

Outbound discards are noted in lanadmin output.

[Ian_4]

- The Packets Outbound Discarded is the number of outbound packets that were chosen to be discarded even though no errors had been detected to prevent their being transmitted.
One possible reason for discarding such a packet could be to free up buffer space.


- The Datagrams Outbound Discarded is the number of output IP datagrams for which no problems were encountered to prevent their transmission to their destination, but which were discarded (for example, for lack of buffer space.)
This counter would include datagrams counted in Datagrams Forwarded if any such packets met this (discretionary) discard criterion.

Hope this helps,

Ian.

[rick jones]

99 times out of 10, an outbound discard is logged in lanadmin (interface MIB) stats because the driver's outbound transmit queue was full.

if you see this happening frequently, you may also want to check the statistics of TCP with netstat and see what sort of TCP retransmission rate you have.

a consistently full outbound transmit queue implies either an overloaded NIC or an overloaded network connection. in such cases, lanadmin statistics should also show a non-zero outbound queue length much of the time.