Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. If you'd prefer to explore, try our test area to get started. And see here for current known issues.

New Member

qos for VTC; understanding stats

So, I'm keeping an eye on my MPLS router for VTC traffic bound between offices.  I came across this link, that describes what some of the stats mean when you issue a "show policy-mapt interface" command.

http://www.cisco.com/en/US/tech/tk543/tk760/technologies_tech_note09186a0080108e2d.shtml

According to this document, if the # of packets is not significantly larger than the number of packets matched, you are filling the TX ring (hardware queue) and packets are then being process or  cef switched at L3.  If I stated that right, anyway.  This can cause performance issues and it's indicative of congestion.

So, I am looking at stats on my router, and I noticed that consistently, there is only ever 1 packet more in the packets count than in the packets matched count.  Does that mean my TX-ring can only hold 1 packet?  I know there is a command to set a tx-ring-limit but if it's really a hardware queue, I'm not sure how you can use a software command to expand it's capacity and I'm not sure what that would do to other functions.

Below are some stats off my router, a 2851.  One thing is that even with congestion I'm not dropping packets so, maybe that's okay. But this is with only one VTC call up and running.  If more calls started up, maybe that could change.    The question is, should I be worried about the closeness of these to counter values?

2555_2851#show policy-map int mu100
Multilink100

  Service-policy output: QoS_POLICY

    Class-map: GOLD (match-any)
      550692 packets, 372363191 bytes
      5 minute offered rate 164000 bps, drop rate 0 bps
      Match: access-group 180
        550691 packets, 372362086 bytes
        5 minute rate 164000 bps
      QoS Set
        dscp ef
          Packets marked 550692
      Queueing
        Strict Priority
        Output Queue: Conversation 264
        Bandwidth 4608 (kbps) Burst 115200 (Bytes)
        (pkts matched/bytes matched) 24142/4505482
        (total drops/bytes drops) 0/0

598
Views
0
Helpful
0
Replies