Connecting Fabric Interconnect to Cisco MDS Switch

[abbasali5]

I am new to Unified Fabric, and trying to understand this.

There are customers who connect Fabric Interconnects directly to MDS switch without any Nexus 5K in between.  If Fabric Interconnects are capable of providing connectivity to LAN and SAN islands then why you would install Nexus 5K switches in between to add an extra hop.

Thanks,

[Qiese Dides]

Hi Abbasail5,

So the Fabric Interconnect is a switch and (the brains) behind UCSM. There are two different modes End host mode and Switching Mode.

In Switching mode your Fabric Interconnect can act as a switch and can be directly connected to a storage array, you can completely by pass having a N5K or MDS switch.

While End Host Mode you have: Unicast Fowarding

DeJaVu - Loop Preventation mechanism, when a Mac Address from Server 2 try's to come to

Server 1 it will be dropped.

Did that make sense Abbas?

Regards,

Qiese Dides

[abbasali5]

Hi Qiese,

I agree with your reply and it totally makes sense.  What I am trying to understand the need for Nexus5K between FI and LAN/SAN Islands.  Most of the customers would connect FIs to TOR switches such as Nexus 5500s.  5500s then connect to Fiber Channel Switches or directly to SAN and LAN networks.

Can you shed some light?

Thanks,

[Walter Dey · Accepted solution]

Hi

Most customers do the following:

- connect FI to upstream e.g. N5k with vPC for Ethernet (and IP)

- connect FI to upstream e.g. MDS for classical FC

This implies, that between blade in the chassis and FI you run  FCoE, integrating FC and Ethernet on the same transport; then on the FI, FC and Ethernet is disagregated.

The other choice would be multihop FCoE, running FCoE also between FI and N5k, and do the disagregation there.

However, if your storage subsystem is FC and not FCoE, I would not recommend multihop FCoE (I see only a minority of customers doing it).

Walter.

[abbasali5]

Thank you Walter!