Ethernet Pause Frame functionality

Andy Bradford amb-plugg at bradfords.org
Fri Feb 3 23:00:38 MST 2012


Thus said Tod Hansmann on Fri, 03 Feb 2012 22:18:47 MST:

> It's a Netgear GS108t-200NAS, if I recall correctly (I'm not currently
> at the office). I'm actually not too worried about the flooding of the
> switch, as  we're only sending 8  MB/s max from the  server. Sometimes
> far less (3  MB/s) and we get  pause frames not based  on the server's
> state, but the clients' states.

It might only  be 8MB/s, but what  is the size of your  packets? If they
are 512 byte UDP datagrams, then that's between 6,144 and 16,384 packets
per second.  Are you sure  that Netgear can  handle that? If  the packet
size is even  smaller, then increase the  PPS and ask again.  How big is
the buffer for forwarding packets on the switch? The specs don't seem to
give these details, but I'm not  surprised about that for a $100 switch.
What about  the rest  of the infrastructure?  I've never  been impressed
with  Netgear.  They're  cheap  and poor  performers.  I  wouldn't  even
recommend them in a home, and definitely not in a business.

But,  it's also  interesting your  point about  the clients  sending the
pause frames. Are they not able to handle the packets? If a client sends
pause frames, that could possibly impact all clients, because there is
only one  server, and ethernet frames  will slow for *all*  clients, not
just the one that sent it, if I'm not mistaken.

Andy



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