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Best of Breed Solutions: Operating Avaya IP Voice Systems on Cisco Networks
One of the questions we are frequently asked by our customers and prospects is whether an Avaya IP Telephony Solution can work on their existing Cisco Network. The question is so prevalent, in fact, that we decided to address it here in our monthly newsletter. Hopefully, the answer will benefit others who were also curious about the topic.
The answer, of course, is yes. Avaya has designed its portfolio of IP Telephony Solutions to be interoperable with most vendors voice and data networks, including Cisco. By using open industry standards Avaya infrastructure and software is incredibly flexible when deploying in a mixed vendor environment. Quite often a total enterprise solution requires a mix of components from multiple vendors, which may also optimize your existing investments in network infrastructure.
Most enterprises need assurances as to the tangible benefits they will gain by integrating components from different vendors. They want to know what features they will gain, and to what concerns they should be alerted. By integrating Avaya Business Communications Applications into a Cisco data network the full range of 700+ Communication Manager features become available. There are two general categories of features. |
- There are those which users directly take advantage of which include Extension to Cellular, Whisper Page, Bridged Call Appearances, etc.
- There are features which administrators take advantage of such as Stateful Failover Between Servers, Enterprise Survivability, etc.
- CTI can help plan which features will make the biggest impact on your business processes.
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What is Important to know
The most important requirement for any deployment of VoIP is that the network (Cisco for this discussion) needs to provide end to end Quality of Service (QoS) based on DiffServ Code Point (DCSP) and/or COS (Layer 2 Class of Service). Avaya servers, gateways, and endpoints can tag packets using combinations of DSCP and/or COS. Tagging is performed independently for signaling and bearer (voice and/or video) allowing for a very granular configuration. Tagging can also be configured independently for each location although it is recommended that the same tagging scheme be uniform throughout the enterprise. In addition Avaya supports RSVP although it is not commonly used today. This assures that the voice communications will work over any data network that supports these tactics for QoS, like Cisco.
This doesn't mean a crazy router configuration, but rather a very similar configuration as to what is used for Cisco's IP telephony. Avaya recommends using Low Latency Queuing(LLQ) for WAN circuits which is what Cisco recommends. Since our CODECs are the same, and based on the Real Time Protocol(RTP) standard, taking advantage of Compressed RTP(cRTP) on lower speed WAN circuits is supported.
Most recent Cisco routers support VoIP and Avaya IP Telephony. This includes the 1700, 2600, 3600, 3700, and of course the ISR's which is the x800 series of Cisco Routers. As far as software, IOS 12.2 or higher is usually recommended. This is because 12.2 fixes a lot of early issues with LLQ and cRTP. Earlier versions of IOS might work just fine depending on the exact configuration.
While often a Cisco configuration for supporting VoIP will insist on upgrading 2600 routers, that is because of the expected additional workload of the routers acting as a voice gateways. It might still be the case that they need to be upgraded if there are unique applications or configurations, or if they do not support QoS, but typically, with an Avaya Solution being implemented for voice, the routers are still be used in the same data centric manner, and so as long as they are not over capacity for CPU and bandwidth usage, there is no need for the added upgrade expense.
Find out more About Avaya.
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