[e2e] Link Aggregation

[Cannara]

Order management is indeed a feature of available network processors used in
newer routers & similar forwarding devices.  Incoming pkts are, at the very
least, identified by source port (channel on a multiplexed port) and time
stamp, and will not be sent from an output queue (or queues) until all pkts
that had arrived before, with the same identifier, have been sent.  This was
common in the design of ASICs for routers and was carried on into network-
processor chips, either in hardware dedicated to order management (IBM,
Vitesse...), or firmware (Intel...).

IEEE link aggregation at Layer 2 (DLC), by the way, has been incorporated into
the design of single-chip switches/bridges, but brings with it some
interesting shortcomings.  One is that the IEEE standard did not allow
multiple paths (links) to be used for any one DLC association.  Thus, if one
has a system capable of filling more than one link's capacity to another
system, link aggregation does no good -- pkts between the two systems are
passed on one link only, as identified in the bridging table entry for the two
DLC ends.  Aggregation only helps when there's a mix of DLC associations.

Alex

Alia Atlas wrote:
> 
> I expect that you may run into problems with one TCP connection because
> most routers try to avoid misordering packets of a single microflow.  Thus,
> even though there may be several interfaces which are part of an ethernet
> link aggregation, the traffic from a single TCP connection would probably
> be directed towards only one of those interfaces (for a good implementation
> which is trying to avoid misordering).
> 
> Alia Atlas
> 
> At 09:56 AM 5/13/2003 -0400, RJ Atkinson wrote:
> 
> >On Tuesday, May 13, 2003, at 08:59 America/Montreal, Valentin Ossman wrote:
> >>Does any one know a link aggregation method for several network adapters
> >>(let's say 4 Gigabit ports) in a way that it will be possible to achieve
> >>one high bandwidth (4Gbps) TCP connection?
> >
> >IEEE have a published standard for Ethernet Link Aggregation.  I'd
> >start by looking that up.  Not clear to me that this relates to the
> >charter of this mailing list however, so followups probably belong
> >elsewhere.
> >
> >Ran