Summary: High tcp retransmits after adding secondary NIC pair

From: joe fletcher <>
Date: Wed Feb 27 2008 - 21:57:45 EST

In the end it turned out to be a bad switch. We replaced the switch hardware
and stats are now clean.



----------------------------------- originally

Got a 6900, 48CPUs, Solaris 10 118833-36. A couple of weeks ago we added in a
second pair of NICs with a view to segregating NFS traffic on one subnet from
the rest of the prod network. The machine has 4 cassinis (ce), one pair on
subnet and one pair on 152. IPMP one both pairs is active/standby. Netmasks
are fffffe00. Card speeds are 1000Base. Under periods of heavy load we see
high retransmission/duplicate packet rates. Clients are mostly v490s with ce
cards running at 100Base. The issue only seems to have appeared since we
in the extra cards.

Can anyone suggest places to look for possible cures? I'm wary of tuning the
stack initially but it remains an option.


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Received on Wed Feb 27 21:58:06 2008

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