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port channels and VSANs 101.


I have a new task to perform and this was not covered all that much in the Cisco training that I had some time ago so perhaps some one could let me know what to expect.

I have two 9216a's and two 9509s for redundancy. A blade will attach to each of the 9216a using one port. Our storage array will be attached to each of the 9509's using a number of ports and it will use LUN masking.

Instead of running lots of fibre around the building, we will be using port channels as the traffic wont be that much.

One VSAN will be created per 9216a and 9509. An 8 port port channel will be used to spread the VSAN over both switches.

So if I plug the blade into one port (eg, fc2/1) on the 9216a and the storage array has one port on the 9509 (eg fc3/1) and the VSAN is number 500, what exactly am I doing? Is the port on the 9216a fibre attached to the port on the 9509 through the port channel? In other words, is it (logically) local to the switch even though it is on another switch?

I am using a 48 port card on the 9216a for the blades and using the 16 port inbuilt card for the port channel to the 9509 which will use a 24 port card that will be used for the port channel and the connection to the storage array.

So, I expect to create a zone as part of a zoneset in the VSAN where I can attach 9216a port fc2/1 to the 9509 port fc3/1. And hopefully this will work.

I hope I have made myself clear here. Am I on the right track?

I can hardly wait to try using SAN extension as I don't have a clue on that one but it is another story. I would love to get better Cisco training on these systems and their expanded abilities.



Cisco Employee

Re: port channels and VSANs 101.

I think the crux of the question is how does one device one a switch communicate with another device attached to another switch. So, assuming the devices are in the same vsan, the switches have a function known as the nameserver. If the devices are zoned together, the nameserver maintains a database that is homogeneous across the fabric. So, the nameserver will tell a device about the other device and then frames will be sent to the target. The routing of the frame is done by the FSPF protocol. In a nutshell, the nameserver knows about everyone on a per-vsan basis and FSPF tells each switch about routing between the switches. This is done on a per-vsan. The port-channel looks like 1 interface to the FSPF and not an aggregate of several interfaces.

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