Transmit Discards; But Router Stats Show No Errors

Our Internet Cisco router is showing no interface errors, but Orion is showing interface transmit discard errors in the thousands. Shouldn't the counts match?

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FormerMember

ok So in doing the show policy map interface command I am seeing the Bandwidth policies that are in place, but its not showing any dropped. I am seeing where it is showing exceded stats, and I would hope that it was dropping those, but not sure on that.

After the exceeded stats it should say actions; and tell you what they are.

police:
          rate 30 %
          rate 460500 bps, burst 14390 bytes, peak-burst 1500 bytes
        conformed 2566350 packets, 2417555326 bytes; actions:
          transmit
        exceeded 3807 packets, 3150229 bytes; actions:
          drop
        violated 393523 packets, 584415562 bytes; actions:
          drop

All comments

kweise

jimm,

I believe that the Orion Transmit Discards show up under Total Output Drops, not under input or output errors when you do a show interface.

If that isn't what you are referring to, the only way I could think the counts wouldn't match is if someone did a clear count on the router during the day. The transmit discards will still show up in the graphs since it would be historical data.

mark_wiggans

You could query these discards yourself, below are a few methods:

*********************************************************

(1)

I would suggest that you install and run a network sniffer

(such as wireshark which is a free download from thwack.com)
on your Orion server.

You can filter for snmp packets coming from this device and

then drill into these packets to see exactly what is being returned from the
device.

*********************************************************

(2)

You could do a MIB Walk.

Check that IfOutDiscards are returning values.

These values will show you what the device is sending out &

help you verify Orion isn't reporting anything wrong.

*********************************************************

(3)

If you have the Engineer's Toolset you can use the SNMP MIB Browser to see what
values the device is reporting.

willhepptemp

Out discards are not errors, strictly speaking. Rather, they're an indication that the device on transmit was unable to enqueue an outbound frame (and, hence, discarded it.) It is an indication of bandwidth congestion. Transmit errors are enqueued or transmitted frames that got borked on the way out.

Also, note that average utilization is a bad indicator of peak utilization. You can have a very low average utilization (depending upon polling interval, general traffic usage of an interface, etc) but still have out discards if there's a spike of traffic greater than link speed + egress buffer

Will

FormerMember

are the interfaces trunk lines? prune only neccassry vlans on the wire. some switches cannot handle 10 20 vlans. stp has to designate 1000 vmacs for every vlan. had same issue with discards errors

nbjeter3

ok so I have a similar Issue. Our primary internet Line, a 100Mb MPLS connection on a cisco 3825, is generating about 2000 discards per hour. No errors. I can't see any reason why it is doing this. Anyone?

nbjeter3

You know what, cancel that. I just remembered we had setup 2 policing policies on that router. It just occured to me that those are most likely the source of the discards.

networkguy09

Orion transmit discards correspond to output drops and transmit errors correspond to output errors, both from the show interface command