Transmit Discards on Serial Int

TimothyR

I have a Cisco router that is getting Transmit Discards on its serial interface. Can anybody give me some more information on this like what/why they are and where to look to fix them?

Thanks.

rknight

If you have access to Cisco CCO website, the following link is helpful

cco.cisco.com/.../technologies_tech_note09186a00800a758d.shtml

Here is a summary;

1. Minimize periodic broadcast traffic (such as routing and SAP updates) by using access lists or by other means. For example, to increase the delay between SAP updates, use the ipx sap-interval interface configuration command.

2. Increase the output hold queue size in small increments (for instance, 25 percent), using the hold-queue out interface configuration command.

3. On affected interfaces, turn off fast switching for heavily used protocols. For example, to turn off IP fast switching, enter the no ip route-cache interface configuration command. For the command syntax for other protocols, consult the Cisco IOS configuration guides and command references.

4. Implement priority queuing on slower serial links by configuring priority lists. For information on configuring priority lists, see the Cisco IOS configuration guides and command references.

Note: Output drops are acceptable under certain conditions. For instance, if a link is known to be overused (with no way to remedy the situation), it is often preferable to drop packets than to hold them. This is true for protocols that support flow control and can retransmit data (such as TCP/IP and Novell IPX). However, some protocols, such as DECnet and local-area transport are sensitive to dropped packets and accommodate retransmission poorly, if at all.


Cheers
Ric Knight