Bandwidth Testing on 3560 Switches

Unanswered Question
ropethic Sat, 01/03/2009 - 11:33

This depends on quite a few variables:

1. What is the appliaction

2. Latency betweem two switches

3. packet queueing enabled

4. packet sizes?

Place as sniffer on one end to a SPAN port and to get a view of the traffic. Look for retransmissions, tcp window errors, etc.

Unfortunately you will need to dig a bit deeper to find a cause.

ropethic Wed, 01/07/2009 - 05:38

Please see url for explaination of different queue methods

http://www.cisco.com/en/US/tech/tk543/tk544/tsd_technology_support_protocol_home.html


Settting a span port to the sniffer will allow you to analyze the conversations traversing your link. The switch will not report Layer 4 errors. Users establish connections using TCP where each segment is assigned a sequence number. if packets are being delayed or dropped a retransmission will occur. The sniffer will identify these as retransmissions.

You can get wireshark sniffer for free.

cisco24x7 Wed, 01/07/2009 - 06:37

Wireshark is a good tool for viewing output file. In a production environment where you

you have to view Gigabytes of data, I would

suggest you build yourself either a OpenBSD

box or Gentoo Linux box and use tcpdump for

this purpose. Tcpdump is best, bar none.


my 2c

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