About Jumbo Frame

[azev]

I have this client that upgraded their 10/100 network to gigabit. Phase one is done a while ago, all switches are replaced with dell 6024F as their core and 5324 as their distribution.
Network size are pretty decent, 2 story building about 120 client with possible of 200 and about 2 racks full of 2u and 4u servers. Just finished phase 2 which is replacing all servers nic card to intel Gigabit over copper server nic. All in all everything works good, and everybody noticed the improvement over the previous network. Phase 3 would be replacing all client machines with newer dell optiplex or dimension with gigabit nic, but that wont happend until late this year.

I have questions about enabling jumbo frame on a mixed 10/100/1000Mbps network.
I would like to enable jumbo frames on the network, especially for the servers. What would be the best step to approach this? All dell switches that we used are Jumbo frame capable up to 10k. Should I enable jumbo frame on the server and core switch, or should I just enable it on all the switches ? Would having jumbo frame enabled hinder with everyday operation of 10/100Mbps network ?
Even when phase 3 is complete, most of the printer we're using are 10/100Mbps, some are still 10Mbps, and I have not heard any word about replacing them any time soon with gigabit network printers.

Any comments or help is appreciated.

Thanks

 

[azev]

anyone ?

 

[spidey07]

I believe every single node on the layer2 network has to support jumbo frames. But then again I've never messed with it. When I've done jumbo frames it is for data centers therefore to reach clients the jumbo frames have to go through a router (layer 3 switch) and get fragmeneted at the IP layer to an MTU of 1500.

 

[Agamar]

Don't think printers will get to Gigabit speeds anytime soon (at least workstation class lasers won't. Maybe some publishing class printer).

 

[Rogue]

Jumbo frames don't make a lot of sense unless everything can handle it. I'd stick with the standard MTU for everything, otherwise you're just adding an additional layer of complexity on top of your network.

 

[azev]

Originally posted by: spidey07
I believe every single node on the layer2 network has to support jumbo frames. But then again I've never messed with it. When I've done jumbo frames it is for data centers therefore to reach clients the jumbo frames have to go through a router (layer 3 switch) and get fragmeneted at the IP layer to an MTU of 1500.

Ok so for now I've decided not to enable jumbo frame as yet. Spidey, got a quick question for you. I have at home cisco catalyst 5505 with sup III, fiber gigabit modules, and RSM module. Let say I enable Jumbo frame on the gigabit module, and keep them on a separate vlan than the 10/100 network. The RSM module is setup to route between vlan. Will this setup forced the RSM to fragmeneted the packets back to mtu1500 and vice a versa ?
I've cannot find any help/sample/guide configuration on cisco website.

Thanks

 

[spidey07]

the router will indeed fragment the packets. however its not a good idea in production as that is done in the processor.

 

[azev]

There's only about 10 (20max) networked printers on this 10/100 vlan, and another 10/100 vlan for the wireless AP/clients. The servers vlan are all gigabit vlan, and the clients computer vlans are also gigabit.

Would a setup with cisco catalyst 5500 with RSM to separate the 10/100 and gigabit vlan is a bad idea for this kind of environment?
Does the complex nature of this network (possible problem) will outweigh the benefit of enabling jumbo frames on the network ?

Thanks