I’m in the mist of troubleshooting possible high
network re-transmissions. I’m basically attempting to capture
enough data to prove that the network is not the bottle neck. I have
complaints from user that their systems are slow but it seems that the
application they are using is the bottleneck. We have several in-house
developed applications that the end users uses that communicates with a SQL
server. They also browse the internet frequently. I’ve been
looking for articles that describe what the average re-transmission rate is for
a standard TCP/IP networked workstation but I could not find any. I’ve
attempted a simple test like running the trouble application and then performing
a simple copy & paste (of a 1gb file) from a file server to the workstation’s
desktop while pinging the SQL server at the same time and I did not see the time
change from <1ms. The application ran slow. Plus the file copied
over without any issue.
A brief description of the network is as follows. We
have 5 floors with each floor having a wiring closet. In each closet we
have a Cisco 3750 cluster of switches. Each floor has fiber running down
to the core switch on the 2nd floor.
The reason we suspect re-transmission is because some
workstations show a high “segments retransmitted” when you run
netstat –s. If I run Wireshark on the suspect workstations what
should I be looking for in the capture? Will I capture re-transmission
that corresponds to the netstat –s output?
Thx.
Albert
