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MDS 9124 interop mode 3


We have an existing MDS 9124 fabric to which I need to add a brocade switch. I understand the solution to this is to change the vsan to interop mode 3, however I am concerned about doing this on a production vsan. Will changing the interop mode on a production vsan interrupt traffic flow on that switch/vsan?

What is the impact of this change?

Cisco Employee


From y experience ,changing interop mode when there is no ISL is non-disruptive, but consider enabling NPIV on the existing MDS switch and putting the new switch in Brocade Access Gateway mode.



Here's what I get for posting something like this prior to coffee....

I actually do have ISL's.

My current fabric looks like this

MDS 9124 Fabric A switch A <-----> MDS 9124 Fabric A switch B

MDS 9124 Fabric B switch A <-----> MDS 9124 Fabric B switch B

The two MDS's are connected via a TE port.

What I really need is a fabric that looks like this:

Brocade Fabric A switch A <----> MDS Fabric A Switch A <----> MDS Fabric A Switch B <----> Brocade Fabric A Switch B

Brocade Fabric B switch A <----> MDS Fabric B Switch A <----> MDS Fabric B Switch B <----> Brocade Fabric B Switch B

If I change the interop mode on both sides of the ISL, will that result in an outage as the TE port re-negotiates or something?

Oh, and NPIV has been enabled on the MDS since they were installed... HP VirtualConnect. Gotta love it!

i like the suggestion of putting Brocade into  AG mode, what is the model of Brocade switch ?



The switch is an HP branded Brocade 300.

I could theoretically also try to put the cisco in to NPV mode yes?

The only thing I don't like about putting the brocade into AG mode is that since the brocade is the newer switch, I would think it would be best to have it be an actual part of the fabric.

Also, in AG mode, does port-to-port traffic within the AG need to traverse the ISL up to the cisco and then back down to the brocade?

nah, you don't want to put Cisco into NPV mode because NPV mode on Cisco is equivalent of AG mode on Brocade. It turns switch into a "dummy" pass-through device. It no longer runs name server, can't create zones etc.

Sure in AG mode all the brains of the fabric are in the NPIV Core, which is your 9124 in the case. If you have array and host connected to Brocade, no their data traffic will not go up to ISL and them come down.

One reason i could think you would go down the route of putting MDS into interop mode would be because of age of the hardware. if you think 9124 will be gone from your shop before Brocade, then maybe it makes sence to setup up like you suggested and later one decomission 9124.  If you setup Brocade in AG mode right now and then you are ready to decomm 9124, that will be a significant project becase you will need to recreate all zones on Brocade.



Agreed. Though I would eventually hope they would all be gone from my network and we'll run FCoE. I'm just waiting for enough budget for a quartet of n5k's.

So back to the original question. Given the ISL's, is changing the MDS to interop mode 3 a disruptive operation?

honestly i have not done it myself but reading documentation i have a feeling it might be disruptive. There are some guides



That was my thought also. it might be disruptive. Problem is there isn't anything that I see in documentation that would suggest that it either is or isn't, and I don't have a non-production pair of switches to test it on

So I'm starting to realize that interop mode is kind of like sticking my head in a bees nest.... Not a good idea.

If I put the brocade into AG mode, you say that traffic doesn't have to traverse the ISL up to the fabric when the array and hosts are both on the brocade AG. If that is the case, how does the AG mode switch know who is in what zone? Is it able to somehow query the fabric switch for zone information?

name server, zoning ..etc is enforced at NPIV core switch. Ports on 9124 that you use to connect Brocade to will display multiple flogi coming from systems plugged-in to brocade, for example:

as you can see i have multiple logins coming from the same port fc1/5, Brocade 4024 running in AG mode is plugged to MDS port fc1/5

c9513# sh flogi data


INTERFACE        VSAN    FCID           PORT NAME               NODE NAME      


fc1/2            1     0x040011  20:29:54:7f:ee:51:88:00 20:01:54:7f:ee:51:88:01

fc1/5            14   0x06007b  20:11:00:05:1e:04:63:17 10:00:00:05:1e:04:63:17

fc1/5            14   0x06007c  50:01:43:80:03:b9:30:18 50:01:43:80:03:b9:30:19

fc1/5            14   0x06007d  50:01:43:80:03:b9:2f:e0 50:01:43:80:03:b9:2f:e1

fc1/5            14   0x06007f  50:01:43:80:03:bd:65:68 50:01:43:80:03:bd:65:69

fc1/5            14   0x060080  50:01:43:80:06:30:55:b0 50:01:43:80:06:30:55:b1

fc1/5            14   0x060081  50:01:43:80:03:bd:65:84 50:01:43:80:03:bd:65:85

fc1/5            14   0x060083  50:01:43:80:03:bd:66:54 50:01:43:80:03:bd:66:55

fc1/5            14   0x0600a5  50:01:43:80:03:be:90:6c 50:01:43:80:03:be:90:6d

fc1/5            14   0x0600af  10:00:00:00:c9:5e:04:78 20:00:00:00:c9:5e:04:78