I'm looking at purchasing a network switch, and the only spec I'm not sure of is one specifying "buffer memory" per port. What is that used for?
1 Answer
It is used to buffer packets in a store-and-forward switch. More buffers are not neccesarily better, and can even make things worse. See the Buffer Bloat phenomenon. Cut-through switches provide much lower latency and do not use buffers.
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3Note though that for some workloads, larger port buffers can offer significant performance improvements. iSCSI SAN traffic, for example. Sep 30, 2011 at 14:52
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@Chris Thorpe, it shouldn't help at all, and due to the buffer bloat problem, could make things worse. More buffered packets leads to more latency.– psusiSep 30, 2011 at 15:02
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@Billy ONeal, I would look for cut-through switches that don't use buffers.– psusiSep 30, 2011 at 15:03
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@psusi: Hmmm... I don't see anything like that available anywhere. Then again, I'm talking about a small (~8 port) switch. Everything available seems to be store-and-forward. Sep 30, 2011 at 15:23