cisco cpu % monitoring

Discussion in 'Cisco' started by yo, Aug 9, 2005.

  1. yo

    yo Guest

    is there a way to log cpu usuage on a 1600/2600 and mem/enviroment
    conditions to the buffered log. I think i have a cisco thats droping
    the wan connection because of high cpu usage.

    thanks
    yo, Aug 9, 2005
    #1
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  2. In article <>, yo <> wrote:
    :is there a way to log cpu usuage on a 1600/2600 and mem/enviroment
    :conditions to the buffered log. I think i have a cisco thats droping
    :the wan connection because of high cpu usage.

    http://groups.google.ca/group/comp.dcom.sys.cisco/msg/44b0c666c38a8841
    --
    Any sufficiently advanced bug is indistinguishable from a feature.
    -- Rich Kulawiec
    Walter Roberson, Aug 9, 2005
    #2
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  3. yo

    yo Guest

    Thanks Walter, i guess you can't have cpu warnings displayed on the
    cisco router log!? I was thinking of setting up mrtg if this was not
    possible.

    Is there any tips that I can use to free up more cpu, such as ip
    route-cache on 1600's and 2600's handling high traffic in/out?


    On Tue, 9 Aug 2005 16:09:36 +0000 (UTC), -cnrc.gc.ca
    (Walter Roberson) wrote:

    >In article <>, yo <> wrote:
    >:is there a way to log cpu usuage on a 1600/2600 and mem/enviroment
    >:conditions to the buffered log. I think i have a cisco thats droping
    >:the wan connection because of high cpu usage.
    >
    >http://groups.google.ca/group/comp.dcom.sys.cisco/msg/44b0c666c38a8841
    yo, Aug 9, 2005
    #3
  4. In article <>, yo <> wrote:
    >

    :Thanks Walter, i guess you can't have cpu warnings displayed on the
    :cisco router log!? I was thinking of setting up mrtg if this was not
    :possible.

    Sorry, I don't know IOS well enough to know the answer to that.


    :Is there any tips that I can use to free up more cpu, such as ip
    :route-cache on 1600's and 2600's handling high traffic in/out?

    I do not work with IOS much, so this is all going by memory of what
    I've read online:

    - the 1600 and 2600 do not, if I recall correctly, have real
    distributed processing of packets, so it is best not to do
    per-packet load balancing with them

    - In the last few major releases, CEF is the most efficient, but
    before that on the low end devices, process switching
    was more efficient than CEF.

    - packet inspection takes real CPU time on the 1600/2600, so use
    minimal 'inspect' and IDS features.

    - on the low end devices, there is a noticable penalty in ACLs
    for the first entry that extracts layer 4 information (port numbers);
    this penalty is not paid in the ACL processing until that point,
    and is not paid again for that packet for any other later entries that
    need the information. Thus if you are CPU bound, move the port checks
    further down or eliminate them

    - if you have ACLs that block all traffic to certain destinations,
    then in many Cisco devices, it is more efficient to remove that ACL
    entry and route that destination to NULL0. I do not know if this
    holds for policy based routing

    - nat translation tables take time and memory

    - syslog takes resources. If you are logging for accounting
    purposes, netflow is more efficient

    - serial console takes a lot of resources. If you need to manage
    the device, telnet/ssh is a lot more efficient; and set up the
    logging levels so that only the really important things get logged
    to the serial port. If you are CPU bound, then sending debug
    traffic to the serial console is really hard on the device.

    - if you don't have a VPN accelerator, then ssh to the device is
    harder on the device than telnet

    - if you don't have a VPN accelarator, any kind of VPN tunnel
    (e.g., IPSec, PPTP, GRE) is a drain on the device CPU.
    --
    Entropy is the logarithm of probability -- Boltzmann
    Walter Roberson, Aug 9, 2005
    #4
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