Catalyst 37xx stacking compatibility

brian.k.clarke · ‎03-23-2011

I've been asked repeatedly about stacking compatibility within the Cat 37xx line (3750, v2, G and the new X series). It's come down to the strong opinions of two different Cisco reps, one of which claims you must be on the same "level" (and pay for it) on every switch in the stack (meaning, if one old 3750G switch is running Enhanced, then the other 2-8 3750-X switches in the same stack would require the IP Services image - $8K/48-port switch = up to $64K), the other pointing to the Q&A doc below:

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Q: Can a Cisco Catalyst 3750-X LAN Base switch be upgraded to IP Base and stacked with any Catalyst 3000 switch?

A: Yes. Once a Catalyst 3750-X LAN Base switch is upgraded to IP Base or IP Services, it can be stacked with any non-LAN Base switch or stack.

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This answer indicates that you can mix & match Standard/Enhanced/IP Base/IP Services images in the same stack, which contradicts everything I've heard up to this point. So, I need clarification/certainly, hopefully from someone who's been out there as an implementation engineer. (For a current customer, this could be a million-dollar question as they refresh their entire closet infrastructure - BTW, HP doesn't charge anything extra for the "full-featured" image.)

It was my understanding that whatever image you update the "master" switch with would be propagated/copied to the others. Is this indeed true? If so, then why would it be necessary to pay for the Enhanced image on every switch in the stack?

Let the discussion begin - this has been coming up very often lately, and could be a competitive deal-killer for Cisco if we all can't figure it out.

Leo Laohoo · ‎03-23-2011

I don't know where to start but let try and put my 2 cents worth ...

1. The "first" generation of 3750, i. e. 3750, 3750G and 3750 v2, has a backplane speed of 32Gb.
2. Starting with the 3750E and to the 3750X, the backplane has increased to 64Gb.
3. Now mixing them. For obvious reasons, you CAN mix a first generation 3750 with an "E" or an "X" BUT the backplane drops to 32Gb (because the first generation 3750 can't negotiate higher than 32Gb).
4. IOS stuff. If you mix your 3750/3750E/3750X in a stack DO NOT USE the "universal" or "universalk" IOS. If your 3750 is, for example, using IP Base, then your "E" or "X" should be using the same feature set and not the "universal" ones.

brian.k.clarke · ‎03-23-2011

Thanks for the response! A follow-up:

I understand that the stacking backplane will be bottlenecked by the oldest switch - so let's get that out of the way. I'm really interested in compatability, and more importantly, COST.

Disregarding backplane performance of the individual switches in the stack, how does the mixing/matching of IOS images work? Again, if the master is in control, and propogates to the others, do we really need to PAY the extreme cost for the image upgrades for each individual switch in the stack?

Leo Laohoo · ‎03-23-2011

If you are upgrading from one IOS version to the other, for example, 12.2(50)SE IP Base to 12.2(55)SE1 IP Base, then there's no cost involved.

HOWEVER, if you upgrade the feature set, then there's a cost involved. For example, 12.2(50)SE IP Base to 12.2(55)SE1 IP Services.

brian.k.clarke · ‎03-23-2011

I understand that, when purchasing an individual switch, but the questions at hand

deal with switch compatibility within a common stack.

Leo Laohoo · ‎03-23-2011

but the questions at handdeal with switch compatibility within a common stack.

I don't understand this bit but if I do understand your question then the answer lies in this: IF you want to add a new switch member to an existing stack, then you must ensure the new switch member has the same IOS version and the same feature set before adding to the existing stack.

Did I answer your question?

brian.k.clarke · ‎03-23-2011

Sorry, but no:

The original post included a Q&A response that suggested any non- "LAN Base" image could be mixed within the same stack, meaning you wouldn't have to license each stack member the same (Enhanced/Base/Services-wise). Plus, if it's true that the "master" switch image is propagated to the others in the stack, it again begs the question why you'd need to pay for whatever enhanced image for them all.

Fact - if I order a 3750G Enhanced image switch today, it will NOT have the exact same IOS image as a 3750X IP Services switch.

I need implementation experience with multiple-model/image switch stacks here, I think.

Thanks again

Leo Laohoo · ‎03-23-2011

If you are using 3750E and 3750X and if you don't know which image to purchase, then use the the IP Base to start with. You can purchase license to UPGRADE the feature set.

I have a number of stacks using both 3750E and 3750X in a stack. I also have the "plain" 3750 a stack with the "E" or "X". All stack members have the same IOS version and the same feature set.

When I add a new member, I always make sure the IOS version and feature set are the same. If it's not, a software upgrade/downgrade is necessarily done to the new stack member BEFORE it's added to the stack.

hobbe · ‎03-24-2011

Hi

ok here is how i have understood that it works.

L2 can stack with L2 only

L3 can stack with any L3 (providing right version of ios)

now comes the tricky part.

L3 can have different licensing schemes.

This does not make the stack break, BUT you might be in violation of your license wich you are not allowed to.

so to make this short

Yes you can stack different licences and it will work, however you might be violating your license agreement AND you might get problems.

Its a little bit like driving a car, you CAN drive faster than the speed limit, but you are not ALLOWED to.

What problems?

Well fx if you have a stack with 2 different licenses and 2 physical switches and the one who is master has a ip services license and the other does not.

IF the ip-services licensed switch fail then you have a master who is then not ip-services but only ip-base and some features are no longer available and some stuff breaks.

so to answer your question

Yes both is right in their own way, but in the eyes of cisco lawyers only "the other cisco rep" is correct. ie you need the correct license for each and every member of the stack.

This is a perfect example that in theory theory and practice is the same, in practice it is not.

HTH

Good luck

brian.k.clarke · ‎03-24-2011

It was my understanding that whatever image was on the stack "master" would be automatically copied to the other switches in the stack. So, if I had IP Services on the current master switch, and I introduced a new switch with IP Base on it, the new switch would get overwritten automatically. Is this not true?

If it is, then my question comes down to - do I still have to pay the $8K license upgrade for each "upgraded" switch in the stack (that's pricing for a 48-port 3750-X), just to be "legal"? For a 9-switch stack, that's an extra $64K (8 x $8K) - obviously a big deal and a possible deal killer (since HP, for example, doesn't charge any extra for their advanced services images now).

Thanks again

brian.k.clarke · ‎03-24-2011

To supplement the above, I'll again refer to the Q&A doc for the 3750-X line:

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Q. Are mixed stacks supported?

A. It depends. The Cisco StackWise and StackWise Plus solutions are flexible enough to allow you to:

• Stack any Cisco Catalyst 3000 switch in the same stack (hardware mixed stack)

• Stack any Cisco IOS Software feature set in the same stack (software mixed stack)

One exception is the new LAN Base models being introduced with the Catalyst 3750-X and 3560-X Series, which can stack only with other LAN Base models.

Q. Can a Cisco Catalyst 3750-X Series Switch with LAN Base software be used in any Catalyst 3000 stack?

A. No. LAN Base models can stack only with other LAN Base models.

Q. Can a Cisco Catalyst 3750-X LAN Base switch be upgraded to IP Base and stacked with any Catalyst 3000 switch?

A. Yes. Once a Catalyst 3750-X LAN Base switch is upgraded to IP Base or IP Services, it can be stacked with any non-LAN Base switch or stack.

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These answers indicate that you can mix IP Services and IP Base in the same stack without a problem (and thus not pay for upgrades for each switch in the stack) - "software mixed stack."

I just need confirmation on this from someone in the field - again, if the master replicates its IOS to the other stack members, there'd never be the issue where another switch becomes the master and thus can't provide the configured features...

hobbe · ‎03-24-2011

You stated

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These answers indicate that you can mix IP Services and IP Base in the same stack without a problem (and thus not pay for upgrades for each switch in the stack) - "software mixed stack."

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Yes you can, but you are not allowed to do that since you are breaking the licensing scheme.

do you see the difference ?

I will try to locate the exact place that I have seen the text that states that it breaks the license.

hobbe · ‎03-24-2011

Actually I think it would be best if you to talk directly to Cisco about this that will give you an absolute answer.

but in the interest of communication.

There is a problem with trying to do this with a 3750x since the 3750x is license based. not like fx 3750G

in the 3750 manual it does say that it might break licensing rules.

However it is my understanding that yes you would be required to buy the feature upgrade for all switches that you want to be part of the stack.

just as you would if you wanted to load the software on them outside the stack.

This is (I think) one part of why Cisco want to proceed to license based switches instead of us beeing able to just download a file.

To many people are doing what they can do instead of what the are allowed to.

As I see it, this is not a compatibility issue, it is a moral issue of how to treat and pay for the licenses that are being used.

brian.k.clarke · ‎03-24-2011

I hear you - problem is, I've gotten different opinions from different (trusted) Cisco reps/engineers on this.

I'm just stuck on that last statement in the Q&A that I posted, which certainly suggests the images don't have to be the same in the stack (and thus maybe payment not required, actually or ethically).