Catalyst 3750G and iSCSI Storage Array

[Delmiro Campelo]

Good morning support community,

I have a quick question that I'm hoping you can shed some light on. I'm planning to build a SAN using a pair of 3750G (early generation). One of the best practices that I'm seeing from the vendor is to set the mtu on the switch to 9000 globally. so here is my concern.

1. Can I run iSCSI traffic on vlan A and network traffic on vlan B on the same switch with MTU of 9000 ? would that create any issues for network traffic?

2. What would happen to network traffic with an mtu 1500 ? would it get dropped or slowed?. 

We are on a tight budget so I don't have that much wiggle room for another pair of 3750s.

Thanks,

Delmiro

[richbarb · Accepted solution]

Hello Delmiro,

1 - You can configure your switch to support jumbo frames in your entire network without any problems with the traffic.

The point is, increasing the mtu to 9000 will allow you to forward any traffic without fragmentation.

2 - Nothing different will happen, the traffic with 1500 mtu will be forwarded normally.

Just remeber that to jumbo frame works you must enable the higher mtu end-to-end.

Richard