We are in the process of implementing an iSCSI SAN and the SAN vendor is recommending that the switches be configured to allow Jumbo Frames (9000 bytes).
My question is whether or not we should be concerned with that. We are running (Cisco Call Manager) voice services over these switches. My concern is that the enabled jumbo frames could create issues for the voice traffic. Granted, we have the QoS configured. And the iSCSI traffic is going to be on a seperate VLAN.
Right now the two switches (that that iSCSI traffic will run on and voice traffic do run on) are connected with a single 1gigabit link. We are planning to make other switchports available and make an etherchannel. But, my concern is that the jumbo frame is going to choke out the link and have negative affects on the voice.
I suppose one solution might be to run redundant links and use per-vlan spanning tree. This would essentially give the iscsi traffic a dedicated link unless there was hardware failure. However, I believe the max mtu size is set globally and would affect all vlans. So, jumbo frames on non-iscsi vlans would still present the same (hypothetical?) risk to the voice vlan.
Any suggestions, comments, feedback, etc would be much appreciated.