Jumbo Frames with 3550-12T?

[admin_2]

I'm planning a small Gigabit Ethernet network comprising two 3550-12T switches, four NFS servers with Intel Pro/1000 T server adapters, and 16 NFS clients with the same adapters. Ideally, the clients and servers should use "jumbo" frames to communicate for read and write requests, as that would reduce server load considerably. For NFS, jumbo frames should be 9+ KBytes, so the request can include 8 KBytes of data plus headers.

Does the 3550-12T support jumbo frames? If so, what is the maximum MTU it supports? Does it support them for Gigabit Ethernet? Does it support them for Fast Ethernet? We've seen potentially conflicting information on this subject.

The Intel adapters claim to support frames that are large enough for our needs, but will they interoperate properly with the 3550-12T using jumbo frames?

Does the 3550-12T's GigaStack feature handle jumbo frames?

If you would like to respond directly, please respond to smorgan@almaden.ibm.com.

Thanks,

Stephen P. Morgan

[Prashanth Krishnappa]

Stephen

The 3550-12T's MTU range is from 1500 to 2025 bytes.

3550-12T(config)#int gigabitEthernet 0/1

3550-12T(config-if)#mtu ?

<1500-2025> MTU size in bytes

Regards,

-Prashanth

[DALE FRANCIS]

This is from the release notes 12.1(9)EA1:

The maximum allowable system MTU for Catalyst 3550 Gigabit Ethernet switches is 2000 bytes; the maximum system MTU for Fast Ethernet switches is 1546 bytes.

http://www.cisco.com/univercd/cc/td/doc/pcat/ca3550.htm

Above url States MAX MTU is 2025

[#4]

I guess I'm confused by the Catalyst 3550 Multilayer Switch Software Configuration Guide. Table 9-5, on page 9-16, indicates that the switch has a "VLAN" MTU capability of 18,190 bytes. See:

http://www.cisco.com/univercd/cc/td/doc/product/lan/c3550/1219ea1/3550scg/swcfg.pdf