[c-nsp] packet loss when servers are brought online

[Christopher Hobbs]

>You mention you're using iSCSI.
>What utilisation rates are you hitting? The 3750 has pretty small
>per-port buffers, so if you are contending one or more ports, you could
>be getting packet loss due to that.
>e.g. you boot a machine, it hits a disk very hard over iSCSI, causing
>contention and packet loss.
>Can you supply a diagram? Showing ports & vlan memberships?
>Also, can you be more specific than "packet loss". Packet loss on which
>path, between which two hosts?


Here's a quick diagram:  http://i.imgur.com/IX8hU.png

Only 4 servers are hitting the SAN at any given time and it's pretty
low utilization.  However, 8 servers are connected to that switch.
I've reformatted both of the machines in question and ensured that
neither are using iSCSI or multiple interfaces.  They're simply a
box-stock Ubuntu 10.04 server (64bit) install with a single NIC
connceted to our internal vlan.

Packet loss is occurring between the new servers and the gateway, my
laptop and the gateway (connected to the same switch/internal vlan),
and between machines on the internal network.  I haven't tested DMZ or
the SAN yet.
--
Christopher M. Hobbs
http://hooobs.github.com/