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
    balancing?

    Thanks a lot!

    Miguel
     
    Miguel Sanders, Aug 9, 2008
    #1
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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
    ports.
    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
    EtherChannel...
    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
    #2
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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
    #3
  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
    #4
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