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Maximum Speed with Catalyst 4503 (Sup4) and WS-X4448 Board


does anybody know about the "realistic" Speed of the 4503 with a Sup4 and WS-X-4448 Board? A customer reported to us, that his Linux-Servers have "only" a transfer-rate of 500Mbit/s, instead of 650Mbit/s using direct connection between the Servers or if they are using a 3Com Superstack. Also, they reported, that the delay is about 150-250microseconds, but if they are using again the 3Com or a direct connection, they've got a delay of about 50-75microseconds...They are using Intel e1000 Gigabit NICs.

I know, that most people would be happy, if they could reach those values, but the cusomer is using very critical and bandwith-taking applications (not sure which exactly..) so he is not happy, that with his new Cisco-Switch the performance is not as good as before.

There are no errors in a "show port" output (no Collissions, no FCS and so on..everything is clear)

The Switch is just running as a Layer2 switch, Spanning Tree is disabled ("standalone switch"). All ports are connected to Vlan1...sure, this is not the best to do so, but it should not impact the system performance, or does it?

Unfortunately, there are currently not too much documents about the 45xx-series on the Cisco-website, and in the Bug-Navigator it is also not listed. Does anybody know, when this will come up? (e.g. a command summary and so on)

And which are values you are reaching with other Gigabit-Servers attached to the Catalyst 4503?

thanks, andy

New Member

Re: Maximum Speed with Catalyst 4503 (Sup4) and WS-X4448 Board

Recall that there are only 6 GbE connections to the backplane on Catalyst 4000 series GbE modules. As a result, there is an oversubscription ratio of 8 to 1 on the WS-X4448-GB-RJ45. The only non-blocking GbE module is the 6 port 1000BASE-X (WS-X4306-GB).

The 48-port Gigabit Ethernet has 48 oversubscribed ports in six groups of eight ports each:

Ports 1, 3, 5, 7, 9, 11, 13, 15

Ports 2, 4, 6, 8, 10, 12, 14, 16

Ports 17, 19, 21, 23, 25, 27, 29, 31

Ports 18, 20, 22, 24, 26, 28, 30, 32

Ports 33, 35, 37, 39, 41, 43, 45, 47

Ports 34, 36, 38, 40, 42, 44, 46, 48

Therefore to maximize performance, you need to evenly distribute the servers across these groups of ports.


New Member

Re: Maximum Speed with Catalyst 4503 (Sup4) and WS-X4448 Board

Hm, that sounds interesting!

Thank you a lot. I have to verify, if they've done their tests with all Servers

producing traffic (the 48Port blade seems to be almost totally used, only 5 or 6 ports which aren't used)

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