Dealing with end of support products / SRST

As a partner engineer, I get this question a lot – “I’m upgrading to Cisco Unified Communications Manager 10.5, can I keep my Cisco 2800 gateway, it still works just fine?”, and I’m sure those of you in the enterprise dealing with routine upgrades also run into these kinds of questions.  The answer isn’t an obvious one, and it opens the question as to ‘how do I know whether my hardware and software will be supported together” and it opens up an interesting conversation.  Notice that i used both the phrases ‘can I keep’ and ‘will be supported’ in the previous sentences – there is a reason for this.

With any manufacturer of technology, both hardware and software undergo an evolution and changes throughout their product life-cycle. These changes both solve and sometimes create bugs. Knowing this, it’s common for a product manufacturer to create complex compatibility matrix’s that show what has and has not been tested to work together.  Sometime there are very obvious changes that make a product no longer function, and these are the easiest compatibility scenarios to work out (and offer a very binary ‘YES’ or ‘NO’ decision metric), but sometimes the issues are much more subtle, and the answer not so clear. How do they make these determinations, anyway; by regression testing of course. The challenge with regression testing is this – where do you draw the line and stop testing?

In recent years, a number of very popular Cisco products have gone ‘End of Support’, including the ISR G1 routers, which include the extremely popular Cisco 2800 series router. In Cisco-speak, ‘End of Support’ means (amongst other things) that no software revisions are going to be created in the future – development has stopped, and the product will continue to exist in the current state – bugs and all.  Just because a product has gone ‘End of Support’ doesn’t necessarily mean that you have to rip it out of your environment and stop using it, but it does mean that generally, the manufacturer is not going to be doing future regression testing using that product.  So in the case of CUCM, the software product moves forward, but time stands still for the 2800 router who has been ‘retired’.

Getting back to the idea of a ‘compatibility matrix’, in the Cisco Collaboration world, this means for us a cross-listing of supported hardware (phones, gateways, servers), software (of many different products), and firmware (both phone firmware and IOS).  Depending on what data sheets you look at, sometimes these documents call out specific ‘supported versions’ but other times they simply call out ‘minimum versions’.  Old documentation isn’t always updated as these recommendations change. So it can be very difficult to know what data to trust, as the information is often conflicting. Back to the ‘CUCM and Gateway’ topic that I opened this blog with, we’re mostly interested in what minimum IOS we need to run on a gateway for a particular version of CUCM.  Well since we know what version of CUCM we want to run, that’s a given value, so we check the compatibility matrix and locate the model of hardware we want to use – and usually we find it, and we find a given release of software we can run, and that is that. However in the case of products who have reached ‘End of Support’ we run into a case where the manufacturer is, in many cases, no longer testing compatibility, so that leads me into my next topic – ‘Does it work?’ versus ‘Is it supported’. But the 2800 routers present an interesting case – the compatibility matrix currently lists them as supported for use as a gateway (which is interesting that they’ve done at all, given the ‘end of support’ status of the device), but it’s important to note that those gateways (due to the most recent version of IOS that they can run) are limited to SRST 8.6. Determining whether your environment can run a supported SRST version is an exercise in itself, and it takes into account multiple complex factors including model of phones, features, minimum firmware releases, etc.

We often find that products that have reached end of support continue to work for a very long time, as their configuration is static and while operational, there are no guarantees that they will continue to function without problems. So what do you do if you choose to ‘operate outside of the support envelope’, you may find that your equipment works fine, or you may find that it’s not reliable, or doesn’t even work at all. At this juncture, you have no recourse aside from removing the ‘End of Support’ component and replacing it with a currently supported component, one for which the manufacturer has performed regression testing and is offering to stand behind.

As a partner engineer, my primary responsibility is to deploy a solution within the manufacturer’s supported configuration, in a way that meets the clients needs. I’m not in a position to offer an expressed warranty that any solution will (or will not) work, I’m at the mercy of the product manufacturer to make those statements, and to stand behind the implementation that I have performed, assuming that it’s in accordance with their advertised best-practices and standards (this includes compliance with published compatibility matrix’s).

So for those of you out there still nursing along those ISR G1 routers, and wanting to go to CUCM 10.5 – will it work – possibly. But be aware that there are limitations with SRST that are not fully compatible with all devices and features supported by your CUCM release, and if you run into issues, the manufacturer is going to offer ‘permissive support’ at best, and there’s going to be very little aid they can offer you if something isn’t working properly, and you’ll be forced to upgrade hardware anyway.

So my advice to you who as end users of the technology, when dealing with decisions surrounding ‘End of Support’ technology, ask yourself this – is a ‘yes’ to the question  ‘will it probably work ok’ all you’re after to be comfortable, or do you need to be able to satisfy a ‘yes’ to the question ‘will the manufacturer support me if something doesn’t work right’. After all, that’s what this really boils down to. Happy upgrades!