Port Channel Best Practice

[matthew-morse]

Hi All,

I have a MDS9509 with port channels going to my Cisco blade switches on my HP Proliant blade enclosure.

I have NO ports left on my MDS9509, but DO have some remaining on the blade enclosure.

The question is, can i port channel from the blade enclosure to another edge switch (MDS9148)?

Is that a supported configuration/Best Practice and what are the ramifications if I do that?

So I'm going from Core, to edge and then to edge switch with port channel.

Thanks,

Matt

[Kris Vandecruys]

Hi Matt,

Short answer: No,a single fc port-channel needs to run parallel point-to-point between 2 devices (Host === Switch). a V-shaped topology is not supported or even possible.

BUT!

What you CAN do is make 2 port-channels, one going to one edge switch and the other to another edge switch.

So you will have something like

     Core

  //          \\

Edge1   Edge2

  \\           //

Blade Switch

You will end up with 2 paths from your bladeswitch to your core, and FSPF math will determine which path is used.  If they're equal cost (seems like you would want this) then load-balancing will (in default config) send Exchanges over both links.

This makes your topology more complex but it's supported. (Conditionally, I made several assumptions about the rest of your fabric )

I hope this clarifies port-channels for you.

HTH,

/Kris

[matthew-morse]

Kris,

This is what I currently have keeping in mind I have two separate fabrics..  Four ports for each switch.

                Core1                    Core2

                 ||||                          ||||

    Blade Switch1                Blade Switch2

I guess this is what I was hoping to do on each fabric, but you state that it’s not supported.

1)      From core to blade and then from blade to edge.

          Core1                           Core2

            ||||                                ||||

    Blade Switch1                Blade Switch2

               ||||                           |||| 

            Edge1                    Edge2

Regards,

Matt

[matthew-morse]

Kris,

Does that make sense?

I have Fabric_A Core1 to Blade1, Fabric_B Core2 to Blade2.

I'm asking if I can add a separate edge switch (9148) to each Fabric?

Core1 to Blade1 then to Edge1

Core2 to Blade2 then to Edge2

Or do I need to port channel off of the director/core (MDS9509) only?

Matt

[Kris Vandecruys · Accepted solution]

Hi Matthew,

Sorry for the misunderstanding,  your to-be diagram cleared up a lot for me :-)

First off, yes, it will work. There's no reason it shouldn't and if you have the external ports free on your 9124e, you can hook up a new switch.

It's far from a conventional design, because blade switches are supposed to go in the Edge. It's not a best practice.

What I would recommend is that you move some of the storage from your edge to the 9148, and treat it as a collapsed core, sharing an edge switch (the blade switch).  You can then ISL the 9148 and the 9509 together into a somewhat sensible topology.

So for one fabric this would be

(disk)---9148  --- 9509 -- (disks) (some moved to the left to free up space for ISLs)

              \          /

               \        /

                9124e

Or you can contact your sales team and look to swap some Linecards with higher port density ones.

Lastly I would like to note that, however you link up the switches, most combinations available to you will 'work'.  So as a temp solution you can go ahead with the (core - blade - edge) scenario.  Just know that you'll be introducing bottlenecks and potential weak points into your network. 

[matthew-morse]

Thanks Kris,

This is good information that I can use to determine how I’m going to implement this SAN and the new 9148 switch.

Matt

[Kris Vandecruys · Accepted solution]

Hi Matthew,

No problem, glad I could help!   If you're satisfied with the answer, please mark the question as answered so other forum users can benefit from this info as well

HTH,

Kris

[matthew-morse]

Kris,

Regarding the port channel configuration.

1) When I port channel off of the MDS9509 with two ISL's. Should I use two different blades on the 9509 or is ok to use a single blade with two open ports?

2) Since I believe my new edge switch (SN6000) will have the NX-OS on it and my MDS has version (3.1.2a), will there be a compatability issue when I go to port channel them together? 

Matt

[dynamoxxx]

1) you definitely want to use two different blades if available, you want to avoid single point of failure.