ZL WESM bottleneck with many RP?

[RicN]

If I understand it correctly the internal uplink and downlink ports on the WES zl-module is a virtual 1 Gbps link (full duplex I suppuse) and the total unencrypted throughput is 2 Gbps.

However, if I am using the full amount of Radio Ports for the ZL module, 156, and for example, on all these RP:s there are one single client associeted and downloading data from some servers on the wired network, and we assume that wireless stations get something like 20 mbps in actual data transfer speed, then the total amount of traffic passing through the WESM would be 156 RP * 20 mbps = 3120 mbps.

Does this mean that the WES module introduces a potential bottleneck if all attached RP:s is sending data at the same moment in time?

Naturly traffic patterns does vary in a real network, but do I think correctly that the WES module only can support around 50 RP with an outgoing stream to the wireless network of around 20 mbps?

[Manfred Arndt]

The internal WES zl ports are 10 Gbps full duplex...so can support 100 RPs sending 20 mbps concurrently.

But not very likely in ANY real-world environment.

For 802.11a/b/g the best case performance is 24Mbps. In b/g compatability mode it drops down to 14Mbps.

As the number of stations per AP increases, the aggregate throughput drops due to the CSMA/CA "listen before talk" random backoff.

And as stations move away from the AP, they use a more robust, but lower throughput modulation rate and throughput drops further.

So even on a good day, with no interference...you won't see that kind of aggregate throughput.

[RicN]

Thank you for your answer!

I must have misread somewhere that the up- and downlink ports were 1 Gbps links!

So there shall never be any problem with performance limitations from the WES module itself regardless of the number of Radio Ports adopted or the encryption method used?

And it should also work well if you load an 5400 or 8212 with four WES modules with maximum 156 RP each?

By the way, if you have several WES modules in the same switch and they are not part of the same redundancy groups, must you have different Radio VLANs also?