Layer 4 EtherChannel Load Balancing

Discussion in 'Cisco' started by Miguel Sanders, Aug 9, 2008.

  1. Hello all

    I am currently using Cisco 3750E StackWise+ Switches. However, it
    seems that this type of switch only supports layer 2 (MAC address -
    src/dest/src and dest) and layer 3 (IP address- src/dest/src and dest)
    hashing possibilities concerning EtherChannel load balancing. Is there
    an (affordable compared to the 3750E) switch available which supports
    layer 4 (TCP port - src/dest/src and dest) etherchannel load

    Thanks a lot!

    Miguel Sanders, Aug 9, 2008
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  2. Well let me explain the background of this question:

    Server A (TSM client) needs to backup to Server B (TSM server) over
    Ethernet. Server A can have multiple TSM sessions to server B,
    resulting in multiple tape mounts. Furthermore each TSM session
    corresponds to one TCP session.
    Server A and Server B both have a layer 4 EtherChannel defined of 4
    interfaces in which the hashing is based on source and destination
    So this means that, whenever Server A starts 2 TSM sessions to Server
    B (= 2 TCP sessions resulting in 2 tape mounts), the EtherChannel on
    server A will balance the load on two switchports (given the used
    hashing algorithm). Unfortunately, since my 3750E only allows layer 2
    and layer 3 EtherChannel load balancing, all load will be placed on
    the same physical port of server B's EtherChannel, only resulting in a
    maximum throughput of only 1 Gbit/s for server A. Ofcourse, whenever
    another server (f.e. server C) starts a TCP session with server B, it
    is likely (75% chance) that it will use another port of Server B's
    Bottom line is that Server A will never get a bandwidth higher than 1
    Gbit/s no matter how many TCP sessions is starts with Server B.

    Do you understand the problem?

    Thnx a lot!
    Miguel Sanders, Aug 9, 2008
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  3. If I look at the 4500 series, it is capable of examining the TCP
    traffic and do load balancing based on src/destination TCP ports.
    However, as already stated, this is an expensive solution and I think
    I will look after something else.
    Unfortunatele, the 10 Gbps ports are already used for uplinks.
    Miguel Sanders, Aug 10, 2008
  4. Miguel Sanders

    Nicolai Guest

    Well let me explain the background of this question:
    I do - and I currently have the same problem. I never get over 1Gbit. Will
    keep an eye on this great post.
    Nicolai, Aug 10, 2008
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