MDS 9000 32-port Fibre Channel Module

[storagegal]

Hello Again,

I am looking over the data sheet for the Fibre Channel switching module, and I have a question about the bandwidth distribution that is delineated on page 2.

I understand that the bandwidth is grouped into 8 port groups of 4 ports each. However, I don't understand how the bandwidth is allocated. The DS says that the card has 32 Gbps total bandwidth (full duplex I assume), and it also says that each port group has 200MB/s sustained bandwidth (full duplex again, I assume).

However, when I do the math, the 2 numbers don't add up. 200MB/s full duplex equals a 1Gbps connection per port group, which would mean that the card has 8Gbps total bandwidth.

Can you explain where I'm missing something here? Is it really the case that the 200MB/s is the minimum sustained (non-blocking) throughput, and that there's a maximum (but blocking) potential throughput per group? Is so, what's the potential throughput range of the port group, and how is that allocated?

Thank You.

[mrfrase · Accepted solution]

Sorry for the delay Julie,

From Tom H.

On the 32-port module, each group of 4 ports shares an internal 2Gbps ingress path and a 2Gbps egress path for a total of 4Gbps

running full duplex. The 32Gbps total module bandwidth refers to the sum

of the transmit and receive bandwidth (full duplex) on all ports.

So to be consistent, the data sheet should say 400MB/s application bandwidth

per port group ((200 MB/s transmit direction + 200 MB/s receive direction). The data sheet will be updated.

[storagegal]

Ah, now it makes sense. Those nasty typos!

If you are updating docs, you should have the tech writers update the 9509 data sheet as well. On the front page, first bullet, it says that it supports 256 ports, and 768 ports per rack, neither figure is correct for the 9509. The port numbers in the specification section on page 5 are correct though.

[mrfrase]

Thanks, I'll get this message to them.