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Etherchannel Load Balancing


I am implementing an etherchannel on a single 3550 switch, with only 2 ports, connecting to a server that supports 802.3ad, which has 2 NIC's.

What I am wondering is, the server is only going to be talking to one over server, so 1 IP 1 MAC.

I was under the impression that a ether channel will only load balance based on there being multiple mac and IP's talking across the ether channel.

If there is only going to be one, will I still be able to utilize both links, for example, if this is a fast ether channel, and the server is going to need to push 140Mb of traffic, will it be able to do so, talking to 1 other server, or will it only utilize 1 100Mb port of the ether channel because its only 1 ip / mac talking, and will never load balance over the second.

Thanks for any help.

Community Member

Re: Etherchannel Load Balancing

I'm afriad you are correct. I've had similar questions with switch to switch Etherchannel for mcast and I was informed by Cisco a single multicast stream would only ever traverse ONE link the EC bundle.

For server to switch EC, I would say it's the same. You can cable it up and watch the packet counters on the switch to be sure.



Community Member

Re: Etherchannel Load Balancing

Your answer under Windows depends on the specific NIC and driver features in your server, and how they are configured. "NIC teaming" is often what it's called. HP, Broadcom, Intel and other NIC vendors each have their own versions.

Some flavors will load balance both transmit and receive; others only one direction. What works for unicast traffic may not apply to multicast. Other features vary.

According to Wikipedia, "In Linux, FreeBSD, NetBSD, OpenBSD and OpenSolaris Ethernet bonding (trunking) is implemented on a higher level, and can hence deal with NICs from different manufacturers or drivers, as long as the NIC is supported by the kernel."


or Google "[vendorname] nic teaming"

Super Bronze

Re: Etherchannel Load Balancing

Don't know specifically about the hash algorithm options, if any, for your 3550 or your server, but one IP or one MAC might not be an issue. Some switches support various hasing algorithm; many which include using both source and destination IP or MAC addresses. Some also support of hashing using IP ports.

Where you will likely still have an issue if you would like to push more than 100 Mbps for a single flow.

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