Fibre Channel (SAN)

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Occasional Contributor
Posts: 8
Registered: ‎07-11-2012

Fabric with more than 2 switches

Hey folks,

We currently have a Dell Blade Enclosure that contains two Brocade M4424 fiber switches. Fabric "A" is one of the switches and Fabric "B" is on the other.

They hook up to a fiber SAN.

We are in the process of purchasing a second blade enclosure and we wish to give it connectivty to the SAN. The plan is to purchase two external Brocade switches that would be mounted in the rack, they in turn would be hooked up to the internal brocade switches of the enclosure.

I've never done zoning for more than 2 switches, how would this play out? Do we need to "stack" the switches?

Can anyone point me to some good documentation or some examples that I can read over.

Many thanks!

Occasional Contributor
Posts: 12
Registered: ‎01-06-2012

Re: Fabric with more than 2 switches

I don't think I 100% grasp your setup, but I'll still put in my 2 cents.

Am I understanding correctly that you have just the two switches in a blade chassis currently?  Or do those plug into another switch?  Is the fiber SAN then your disk array?  (It seems everyone uses the term a little differently.)

If it is just those two switches into your disk array, then I would think it would make sense to put other brocade switches in your rack and connect both blade enclosure switches into those.  The new external switches would then be your primary switches and the ones in the blade enclosure would be secondary.  You would ISL those in the enclosure into the new switch.  Zoning isn't really any different with multiple switches.  There is a Brocade Secure SAN Zoning Best Practices document that has some good info in it.  The Fabric OS Admin Guide also has a little bit of info in it for ISLs.  You can do all your zoning from your principal switch and that pushes the info to all switches in the fabric.  Actually, you can zone from any switch in the fabric unless you prohibit it, but it is best to do management activity on the principal, and it is best to make the "strongest" switch your principal since it does have a lot of things to do.

So, basically, it would be kind of like this:

disk array <--> new principal switch <--> blade switch1

                                                     <--> blade switch2

(drawing in text isn't my specialty, both blade switches into the principal)

I believe you can also do access gateway mode, but I don't have mine set up like that, so I can't speak to that.  We have Brocade B type switches, but I don't think there is a huge difference between B and M.

I should probably also mention that changing the fabric principal I believe requires a reboot which is disruptive... but if you have redundant fabrics you can do one at a time and not lose connectivity.

Hope that helps!

Annette

Occasional Contributor
Posts: 8
Registered: ‎07-11-2012

Re: Fabric with more than 2 switches

Correct I currently have two Brocades which are internal to the blade enclosure. Thats it.

We are going to add 2 external brocades to the environment to allow more devices to talk to the SAN.

I wasn't sure what the right terminology of how I essentally take the 2 existing brocades and "merge" them with the external ones we are going to purchase essentially.

So ISL is the way, I understand I need a license for that right? Do I just conifgure 2 ports on the existing brocades as E_PORTs and then plug fiber cables from them to the new brocades where I would configure E_Ports as well? Is the zoning then still just as if only 2 switches were involved where I zone the target and destination and thats it?

Example:

Server X  HBA ------>zoned to  ------>SAN

or is it now:

Server XHBA ------>zoned to-----> new switch----> zoned to------>SAN


Occasional Contributor
Posts: 12
Registered: ‎01-06-2012

Re: Fabric with more than 2 switches

I have never needed a license for creating an ISL.  However, if you want to do ISL Trunking, I think you need a license for that.  I have not done that in my environment, but it is pretty much like combining multiple physical ISLs into one logical ISL.  I believe it provides for enhanced network performance and fault tolerance.  I have multiple switches with multiple ISLs between them and I do not use trunking, so that part isn't necessary.  Just as an FYI, best practice is to have 2 ISLs configured for redundancy between switches, though with dual fabrics, you technically have redundant paths if you don't have the ports for multiple ISLs.

As long as your port is set as a possible E port, it should allow for ISL.  The Fabric OS Admin Guide (I've been looking at the one for FOS 6.4.0) lists multiple scenarios on merging fabrics.  I don't know how you "lock down" your switches in your environment, but I have learned to not change the default zone to noaccess on the switch I want to add because then it will not merge.  That setting will push from the primary switch, though.  I imagine your new switch will have nothing defined on it for zoning, so you should just be able to plug the ISL in and the two should merge together.  I always do one fabric at a time in case something bad happens (hasn't yet).  Also, make sure you change your domain ID on the new switch.  All domain IDs in a fabric have to be different or the switches won't join.

As far as zoning, you will zone like it is just one big switch.  If you use webtools, unfortunately it will not list each switch in your fabric in the zone tab, but it should still list the WWNs logged in to the fabric.  You would zone server X hba to storage.  You will just find the hba listed under a different switch.  You don't have to worry about adding anything extra because it is a different switch.

Again, I only have the B series, not M series, so I'm not really sure if there is a big difference in things like webtools, but I imagine they must be similar.

Hope that helps!

Annette

Occasional Contributor
Posts: 8
Registered: ‎07-11-2012

Re: Fabric with more than 2 switches

Thanks that does clear up a bunch. I was stuggling with grasping how the switch looks once "merged".

I think I have a better idea now. You are correct the 2 external Brocades will be blank with no zoning when introduced.

I have used the external Brocades web tools and compared it to our Mseries Brocades, they are identical. Which is nice!


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