Jumbo Frame on Cisco Switch Interface

CSCO12094806 · ‎07-01-2018

Hi, we are in the middle of cisco 3650-24TD-S switch installation.

we have 2 qty C3650 switches (in a stack) to connect check point firewall and VMWare Exsi 6.5 host (fujitsu cx 400).

vmware host will connect to both switches (example port 1 of server will connect to port 5 of sw-01, port 2 of same server will connect to port 5 of sw-02) and will configure LACP on switch side (sw-01 port-5 & sw-02 port-5) and server side (port 1 & 2).

we are looking for to configure Jumbo Frames on Switch side

As per my under standing default is 1548 bytes and switch will support up to 9198 bytes.

could you please help me to understand following

1. what is the advantage of configuring jumbo frame valu on cisco switch interface.

2. how can we configure jumbo frame on switch.

3. how can we configure new jumbo frame value for Server connected ports (sw01- port5, sw02- port5).

4. if interfaces are in etherchannel group (sw01- port5, sw02- port5 are in same etherchannel group), how can we configure jumbo frame for these ports , its in physical interface mode on etherchannel interface mode.

Joseph W. Doherty · ‎07-02-2018

NB: I haven't worked with a 3650/3850, so my answers are generic. Specifics should be in your configuration and reference guides for your switch model and its IOS version.

#1 it allows the switch's port to support jumbo frames. (NB: not all switches support jumbo enablement per interface.)

#2 depends on the switch. (Also assumes switch and/or switch interface supports jumbo. BTW, keep in mind there's no standard for jumbo size, so you can run into issues between different devices that don't support the same jumbo max.) Some switches you enable jumbo globally (e.g. 3750). Some switches you enable per interface (e.g. 6500). Also some switches only support one jumbo size, some allow setting jumbo size per interface.

#3 depends on the server. Check interface configuration options.

#4 again depends on switch. All etherchannel links should be configured to support same jumbo sizes. On a switch that only supports jumbo globally, enabling that should do the trick. For those that support jumbo per interface, you would need to insure, again, all links set alike. Some of the latter might require setting each etherchannel link while some might allow one setting on the port-channel interface.