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Intel MAC Compatibility with 3560/Other Catalyst Switches

Some of our users recently reported problems with their new Intel based Macintosh computers when we upgraded from old Extreme Summits to Catalyst 3560 series switches. They report sluggish response from the network. We have checked the ports for negotiation issues and errors and do not find any. Suspect the Intel Mac; but wanted to find out if anyone else is experiencing the same or has suggestions. Thanks.


Re: Intel MAC Compatibility with 3560/Other Catalyst Switches


to my understanding MAC issues should not be the cause of your issues. Either the Ethernet frame is standard compliant, then there should not be an issue with Catalyst switches and no port errors. Or the Ethernet frames or MAC in use is non standard then the switch would report an error.

Network response times depend on many things and negotiation might be the first thing to check - as you did. I would still recommend fixed settings for port speed and especially duplex. Just to avoid also intermittend problems (f.e. between PC reboots).

Have you also checked for MTU and TCP window size settings? What else did change when you upgraded to the 3560s? Did you also check Router and switch ports for duplex and speed settings?

Hope this helps! Please rate all posts.

regards, Martin


Re: Intel MAC Compatibility with 3560/Other Catalyst Switches


in addition to Martin´s post just a thought: you might want to toggle the ´flow control´ settings on the 3560 to match whatever you have configured on your Macintosh´s. The 3560 ports can only receive, and not send, pause frames. The configurable options are:

flowcontrol {receive} {on | off | desired}



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Re: Intel MAC Compatibility with 3560/Other Catalyst Switches

We have a similar problem with the new Intel Macs. We used to have around 50% packet loss! One thing that I verified is that when I remove the voice VLAN configuration option from the switch port where the Intel Mac is connected, no packets are lost. By the way, all the QoS options are kept intact

At the moment we are still in investigating/testing issues regarding timing, chip set incompatibility(?), ...

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