Layer 4 EtherChannel Load Balancing

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!


Reply to
Miguel Sanders
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4500 series minimum. Thats certainly more expensive the the 3700 series.
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Is there a reason you specifically need layer 4? Only reason I really see is for it is multiple services on a server that are max'ing out, i.e email and web on a single server with email taking 100% of the bandwidth. If thats the case, it's cheaper just to add more servers and break out the services on to individual servers.


Reply to
Brian V


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!

Reply to
Miguel Sanders

I don't know of any switch that supports the type of EtherChanneling you need. How about installing 10Gb/s cards in the two servers and connecting them back to back?


Reply to

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.

Reply to
Miguel Sanders

I do - and I currently have the same problem. I never get over 1Gbit. Will keep an eye on this great post.

Reply to
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