CAT 6509 monitor port and etherpeek?

[d.higginbotham]

I have been asked to get some network utilization numbers. I have a copy of Etherpeek network analyzer, to quote their manual:

"Typically, switch vendors offer a monitoring port as standard issue on their devices to allow a network or protocol analyzer to be connect to the switch. The monitoring port receives or mirrors all traffic to and from one or more stantdard ports on the same switch."

Does the 6509 offer such a feature? If not what is the best way to get a percentage number for network utilization.

TIA,

David

[glen.grant]

Yes the 6509 supports "span" which is what you would use to monitor 1 or more ports or a particular vlan . If spanning vlans you have to be careful not to oversubscribe the monitor port .

[d.higginbotham]

Great. How do I do this? I will be spanning only one VLAN? Are there any gotcha's? like overloading the port etc.? Is there a rule of thumb threshold number to be sure I don't overload the port? I know, I know, lots of questions and no answers, story of my life :) Thanks much

[altaf007]

Check this out

http://www.cisco.com/en/US/products/hw/switches/ps679/products_configuration_guide_chapter09186a008007ef1f.html#29723

[d.higginbotham]

Thanks, that's a great help. What happens if I span an entire VLAN to one port? VLAN has maybe 200 hosts. Will that impact network performance noticably?

[t.baranski]

SPAN doesn't cause a performance hit on the 6500 series. You may overload the SPAN destination port if the aggregate amount of traffic you're SPAN'ing is greater than the port's capacity, but the only consequence is dropped SPAN packets.

[d.higginbotham]

Thank you, that makes sense.

I have a related question: will the results of

sh top util background

return an accurate measure of network utilization?

[t.baranski]

It should, but sometimes software bugs can get in the way.