Re: port monitoring

In article <1150920984.663354.16890@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
stopnowgo <adam.rothschild@xxxxxxxxx> wrote:
Does port monitoring cause a performance hit on a switch, especially if
several (or all) of the ports on the switch are monitored by one port?

It depends on the switch design.

And of course if the total volume monitored exceeds the transmission
capacity of the monitoring port then you will have problems.

We have no user complaints but do not fully understand what the port
monitor command does to the performance of a switch. We have Cisco
3548's. If performance is affected are there any commands that can show
us what is going on. Any help or suggestions is appreciated.

show cpu would show the performance effects.

I don't recognize the 3548 model at the moment. Is it better known
as a 3548XL ? The 3500XL series is an older generation of switches
and I don't know anything about the internals.

On the newer Cat3550 and Cat3750, all the packets flow through a common
bus, with a bit set in the header for each port that is to receive the
packet, so there is no particular performance drop for monitoring
(except any involved in selecting which packets should be monitored)
as no extra copies of the packet get made on the bus.

.

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