We have 3500Xl series switches and some are running port monitoring so we can gather data on what kind of traffic is flowing through our network. The question is if 1 ethernet port is monitoring all the other ethernet ports on it, what kind of performance issues could we expect, if any. Is there a way to show the performance stats of the switch as well. For example, see below.
If you are monitoring all the ports like you have shown you are going to overrun the monitor port if there are running any traffic at all and it will probably give you an inaccurate picture it will probably drop packets .
I have looked at the monitoring port stats and it shows no dropped packets. I am assuming the load of all the ports on the monitoring port is being handled without loss. So our data should be accurate, I didnt realize that maybe we dont have as much data flow as I expected. I do not quite understand the difference between what monitoring all ethernet ports, the uplink (gigabit), and the vlan differences are. I figure that all three should have the same total traffic, I realize that is not so, I just dont know why?
These older switches use a blocking, shared memory architecture and shared buffers for groups of 4 ports. One performance condition that is possible in this type of scenario is intermittent packet loss within the group of ports when traffic is high. This condition becomes probable when utilisation of ports start exceeding about 70% of bandwidth simultaneously on all ports. The symptom is intermittent because of the nature of traffic is typically bursty
Monitor port is 48.
Servers are 45,46,47 -100MB
Let's say a backup is run on the servers and all servers start to hit 70% of available bandwidth. If port is monitoring, then this is = 3 x 70MB = 210MB which exceeds monitor port.
but the server ports could intermittently start dropping traffic because of available buffer taken up by monitor port. There's no real way to determine at what rate this will happen but something to keep an eye out for. You may isolate the monitor port to it's own group of 4.
We are pleased to announce availability of Beta software for 16.6.3. 16.6.3 will be the second rebuild on the 16.6 release train targeted towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are looking for early feedback from custome...