[j-nsp] ex4500 best-effort drops nowhere near congested

Jeff Wheeler jsw at inconcepts.biz
Wed May 8 10:44:04 EDT 2013

On Tue, May 7, 2013 at 4:01 PM, ryanL <ryan.landry at gmail.com> wrote:
> good discussion. the tl;dr - nothing i can do about it. right?

You can add LACP/ECMP ports/paths to reduce the chance that packets
need to be buffered so long that the buffer becomes full.

To use a dirty word, flow-control might be an option as well.
However, you need to carefully test the particular switch and software
to see if it works with any sanity.  Also remember that flow-control
is likely to effectively cause HoL blocking on a port transmitting a
lot of traffic toward another port that is busy, and other ports which
aren't.  For example, you would not want to send flow-control to a
10GE storage server's port that is transmitting to any 1GE ports
because it would likely be harmful to storage performance for all
connected hosts, whenever just one host's port is full.  I personally
think that the complexity, buggyness, and potential gotchas of
flow-control far out-weigh the small potential gains.

Jeff S Wheeler <jsw at inconcepts.biz>
Sr Network Operator  /  Innovative Network Concepts

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