VLAN Traffic Counters

[dcheng.dns]

Are there any documents describing the VLAN traffic counters on a 6500 w/Sup II MSFC running hybrid? In particular, I'm looking for something that might describe why I am seeing extremely low values for the input/output traffic counters. From looking at the layer 2 information, I know that the traffic that is passing through is significant, but when I check the VLAN traffic counters, I am seeing something like 1kbps. I'm gathering these statistics via SNMP into cacti, but a manual check of the interface counters reflects the same results.

Am I forgetting something basic?

[a-vazquez]

There is a single counter for all suppressed traffic. These commands all display the same discard count, which shows the total number of packets discarded for all three traffic storm control modes, on all interfaces or on the specified interface.The packets that does not satify the MTU level will be discarded.For further information verify the following URL:

http://www.cisco.com/en/US/products/hw/switches/ps708/products_configuration_guide_chapter09186a0080160a9f.html

[krjohnson]

Your answer has no bearing on the original question.

He, as I, would like to know how to view traffic levels on individual vlans. It appears to be an issue with switching occuring in hardware vs software. If I force a tcam error (too many ACLs on an interface) the 6500 moves to software switching and all the vlan counters start to indicate the correct traffic levels per vlan. Clear the error and the vlan counters drop back to indicating a few Kb of traffic even though I know the traffic is actually in the Megs.

[dany.datacraft]

Hi,

I have no supporting document on my arguments below, however, I've faced similar questions in the past, and this is what I believed.

VLAN interface is a layer 3 interface, hence if the high traffic you mentioned is within the same VLAN (layer 2), it would not increase the counter of the VLAN interface. Try creating inter VLAN traffic, the counter should increase accordingly.

Dany

[b.henshaw]

That's an interesting comment, kr.

I've observed similar behaviour WRT traffic (including inter-VLAN traffic) not incrementing the SVI counters. I never tried pulling tricks with TCAM errors to isolate the issue though!

We're currently looking at implementing a monitoring system which can query the CISCO-CLASS-BASED-QOS-MIB to get per-VLAN stats. (which we should be able to do because we're using hierarchical service policies on metro switches)

Note that there's a module to do this in RTFW/Torrus but we may not end up using this.

[anton.elita]

Hi,

we have now exactly the same problem - SVI accounts twice or even less packets and bytes. I am still in research why. The issue could be IOS version, but I am not sure. The current IOS is c6msfc2-pk2sv-mz.121-19.E1

Any help will be greatly appreciated.

Anton

[anton.elita]

Hi,

a good answer is at http://www.cisco.com/warp/public/473/35.html

only first packet will be routed, the other ones - switched, not going through SVI.

best regards,

anton