Re: Problem with etherchannel between 2 3550 FXs

>:I have a 3550's in different buildings with ~2km of multimode fiber
>:between them. Until we upgrade to singlemode, we want to use
>:etherchannel to get us to at least 400mbps.
>
>:The link works great, but can't seem to get more than 100mbps over the
>:link.
>
> In the configuration portion you included, you did not have any
> command explicitly setting the mechanism for a selecting particular
> link for any one connection.
>
> For any constant number of active links, the choice of links for
> any one connection is deterministic, based upon the source
> and destination MAC addresses. Essentially it takes some number
> of the final bits of each of the source and destination
> MACs, performs a logical operation on them (e.g., XOR), and
> the numeric result selects which of the links is used.
>
> You get to choose which logical operation you want, but for any
> one source + destination pair, the result is going to be constant
> within the chosen operation.
>
> The implication of this is that if your traffic is all between
> two fixed MACs (e.g., if there is a routing interface on
> either side of the link) then the traffic would all go over
> one link. Or if the sources differ but the destination is
> the same each time, and you happen to have chosen the logical
> operation that ignores the source MAC, then it'll end up going
> over the same link...
>
> EtherChannel is not really designed for "load-balancing" as such:
> it is more a way to allow multiple connections (between different
> systems) in parallel.
>
>
> If I recall correctly, you can also select per-packet load balancing,
> but then you run the risk that packets will arrive out of order,
> which might matter very little or might matter a lot in some cases.
> (e.g., for TCP with Selective ACKs turned on, it might be fine,
> provided you aren't fragmenting packets; but for multimedia streaming
> out-of-order packets can be big trouble.)


So what do I need to do in order to get these 4 links I have to combine
together to get ~400mbit? Is there some bit of configuration that I am
missing?
.

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