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New Member

MDS 9506 ISL between two sites

Hello, currently we have two locations that are about 1 mile away from each other (the Pas location and the Alton location). In Pas we have mds1 (vsan100) and mds2 (vsan200). Each host has two hbas - one connects to mds1 and one to mds2. Each storage array is also connected/balanced on each switch. If one switch dies then everything will run on the other switch.

For some reason there is an ISL between mds1 and mds2 (vsan300). It seems to be of no value since every storage device and every host is already zoned to both switches. I would like to remove it as it does not seem to server any purpose. Any thoughts?

The Alton location is almost identical to Pas. It has alt_mds1 and alt_mds2. All hosts and storage are zoned to both switches. It has the vsan100 and vsan200. It also has a similar ISL between the 2 local switches (I'll likely remove this as well).

We are connecting the two sites with dark fiber because some of the AIX hosts in Alton need to connect to the DMX4 in Pas. This will be like long patch cables between Pas and Alton. We will connect Pas-mds1 to Alt-mds1 and Pas-mds2 to Alt-mds2 and then zone the AIX server in Alton to the DMX4 in Pas. Below are the proposed steps.

Remove ISL (vsan300) between MDS1 and MDS2 in both locations (after verifying that vsan300 is not being used)

Plug in two new 4Gbps Long Wave, Single Mode SFPs into each MDS switch

On Pasteur_mds1 create vsan101

Add 1 dmx port to vsan101

On Pasteur_mds2 create vsan201

Add 1 dmx port to vsan201

On Alton_mds1 create vsan101

Add HBA1 port from AIX p520

On Alton_mds2 create vsan201

Add HBA2 port from AIX P520

In Pasteur Plug in 4 ISL cables - two in mds1 and two in mds2

In Alton Plug in the other ends of the 4 ISL cables - two in mds1 and two in mds2

Verify that the mds ports show as E ports (no other config required unless we choose port channeling etc.)

Zone each HBA for Alton p520 to the appropriate dmx port

Activate and distribute

As we continue to add new AIX hosts in Alton that need to connect to the DMX4 in Pasteur - we will add the new HBAs to vsan101 and vsan201 in Alton.

We have 4 ports used for AIX on our DMX4. With this design we would leave one port in vsan100 and 1 port in vsan200 in Pas. These two ports would be used for connecting local Pas servers. We would then put the third port in vsan101 and the forth port vsan201. These 2 ports would be used by servers in Alton that need to connect to the DMX4 in Pas.

Does this plan make sense? Is there a better approach?

Thanks - Brad

Cisco Employee

Re: MDS 9506 ISL between two sites


Makes perfect sense to me. The ISLs, (VSAN 300) might have been put in place to facilitate a single fabric at each location for a management point of view. If you use Fabric Manager, you will now have 2 fabrics (once distance ISLs are in place) and you will need the licensed version of Fabric Manager to be able to view both fabrics at the same time. Without the licensed version you can view/manage only 1 fabric at a time.

Your plan to add the AIX hosts is solid. If you put the distance ISLs in VSAN 101/201 you might want to make sure that they are configured as E and not TE ports. If you leave them as TE and do not prune off VSAN 100 and 200 will try to merge across the TE ports. My suggestion if to hard code the ISLs as E ports in VSAN 101/202 respectively, or leave them at the default of TE (trunking E ports) and only permit VSAN 101/201 across those ISLs. Same applies if you port channel the 2 links. The port-channel can be configure as E or if it is TE, prune off VSAN 100 and 200 respectively.

Hope this helps,



Re: MDS 9506 ISL between two sites

Spot on with Mike,

I guess the only other option is to utilise IVR which requires an additional license and would be pretty hard to justify for such a simple setup! :)

Good luck!

New Member

Re: MDS 9506 ISL between two sites

Guys thanks for the info. One more question. My DMX4 has 4 ports for AIX. I'm planning on putting 8c1 in vsan100 and 9c1 in vsan200. All the hosts at Pas will have one hba in each vsan and will connect to both 8c1 and 9c1. I will put ports 8b1 in vsan101 and 9b1 in vsan201. All hosts in Alton that need to connect to the dmx4 in Pas will have one hba in 101 and 1 hba in 201. Because of a power problem in Pas it seems that most of the new AIX servers will go to Alton and connect to dmx ports 8b1 and 9b1 throught the new vsans.

This will put lots of stress on 8b1 and 9b1 FA ports with very little stress on 8c1 and 9c1. It would be nice to spread some of the new AIX servers onto 8c1 and 9c1 to help balance the FA ports. The problem is 8c1 and 9c1 need to be in vsan100 and vsan200 in Pas so that the few hosts in pas can access those ports. Any ideas to help balance the load? I'm not familiar with IVR's but it looks like the switches have the Enterprise license.

Thanks Brad

Cisco Employee

Re: MDS 9506 ISL between two sites

Agreed...I see nothing in Brad's post to suggest IVR. Cost more, is more complicated to configure and debug, and friends don't let friends do IVR without a good reason :)