Maximum throughput of 3,640?

Discussion in 'Cisco' started by Joop van der Velden, Nov 5, 2006.

  1. Yehavi Bourvine (58-4279) wrote:

    > I have a Cisco-3,640 with dual FastEthernet card. It does routing between the
    > two interfaces, and I've found that at 50Mb/sec the CPU usage is 100% (most of
    > it in interrupt mode). I've enabled CEF and IP ROUTE-CACHE, removed the access
    > lists but it still the same bottleneck. Is this the maximum that this router
    > can get to?


    Yep. See for example:
    http://www.cisco.com/warp/public/765/tools/quickreference/routerperformance.pdf

    --
    Joop van der Velden -
     
    Joop van der Velden, Nov 5, 2006
    #1
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  2. Hello,

    I have a Cisco-3,640 with dual FastEthernet card. It does routing between the
    two interfaces, and I've found that at 50Mb/sec the CPU usage is 100% (most of
    it in interrupt mode). I've enabled CEF and IP ROUTE-CACHE, removed the access
    lists but it still the same bottleneck. Is this the maximum that this router
    can get to?

    Thanks, __Yehavi:
     
    Yehavi Bourvine, Nov 5, 2006
    #2
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  3. Joop van der Velden

    Guest

    Joop van der Velden wrote:
    > Yehavi Bourvine (58-4279) wrote:
    >
    > > I have a Cisco-3,640 with dual FastEthernet card. It does routing between the
    > > two interfaces, and I've found that at 50Mb/sec the CPU usage is 100% (most of
    > > it in interrupt mode). I've enabled CEF and IP ROUTE-CACHE, removed the access
    > > lists but it still the same bottleneck. Is this the maximum that this router
    > > can get to?

    >
    > Yep. See for example:
    > http://www.cisco.com/warp/public/765/tools/quickreference/routerperformance.pdf


    Above is an excellent document.

    How much is not at interrupt level?

    Check that you are not doing unnecesary local routing.
    i.e. maybe allow ICMP Redirects.

    On a hard pressed router make sure that it is not getting hit
    with a lot of broadcasts. For many purposes you can filter
    all IP broadcasts with an ACL (maybe you need to allow DHCP).

    access-list might be

    permit dhcp (don't know exact command right now)
    deny ip any host 255.255.255.255
    deny in any host x.x.z.255 ! x.y.z for local subnet
    permit ip any any


    Might be worth trying CEF and plain fast switching.



    conf t

    ! for CEF

    ip cef ! or os if just cef?

    int fast x
    ip router-cache cef
    ! repeat for all interfaces

    ! for fast switching

    conf t
    no ip cef

    int fast x
    no ip route-cache cef
    ip route-cache
    ! repeat for all interfaces

    I know that some people assume that CEF is best but
    if it were me I would check.

    As mentioned by me a few minutes ago in another thread
    try to get rid of buffer allocations and frees.

    If you like post
    sh buffers

    I now do not hesitate to increase buffers manually to prevent
    misses and failures provided that there is SUFFICIENT
    MEMORY if I suspect that a router is under any kind of stress
    and shows significant misses or failures.

    3640 is not a fast router by current standards.
    >From the posted link


    50,000 - 70,000pps 25.6 - 36Mbps

    These are very conservative numbers since Cisco assume
    64byte packets and to get 200Mbps
    (i.e. Full Duplex 100M) you will need an average packet size of

    (200,000,000/8)/50,000 bytes = 500 bytes
     
    , Nov 5, 2006
    #3
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