In the worlds of VoIP and IP Telephony (IPT), there isn’t really a “one size fits all” best-practices model for monitoring performance and call quality. Depending upon whether you’re talking about Cisco or Avaya solutions, how you “optimally” monitor a call changes. This post deals specifically with monitoring Avaya calls.
Avaya Call Monitoring
To the best of my knowledge, there aren’t many monitoring solutions providing detailed metrics on Avaya calls. Although Avaya provides a proprietary monitoring tool, it offers high-level views without the details necessary to quickly isolate and troubleshoot problems.
Network Instruments solutions, however, offer a comprehensive offering for monitoring Avaya traffic.
- Link Analyst – Monitors overall network resource and Avaya system health
- Observer’s VoIP Expert –Tracks the entire Avaya call from set up to tear down. Observer integrates Avaya proprietary decodes such as CCMS (call setup) to provide the detailed views you’ll need to quickly troubleshoot the problem. Monitor quality on an aggregated or per-call basis.
- Observer Reporting Server – Provides high-level views of Avaya traffic and performance as well as all other network activity. Reports call/server details.
- GigaStor – Captures and stores terabytes of network-level packets for analysis and reporting. Reconstruct and replay VoIP calls. Review long-term performance and drill down to the packet level.
Optimal Avaya Call Monitoring
As I mentioned before, the placement of your call monitoring tools depends upon which IPT company you choose. Cisco, for example, uses the call manager to initiate the call setup. Once the call is established the connection runs from headset to headset.
With Avaya, the C-LAN (control processor) handles call setup and teardown while its MedPro (media processor) always stays at the center of the RTP stream. To properly monitor the call, the analyzer needs to monitor the four states of the phone call:
- Setup (OFF HOOK message) – C-LAN to Phone
- Active (RTP data is being sent) – MedPro to Phone
- Teardown (ON HOOK) – C-LAN to Phone
- Closed (Call ended via setup messaging) – C-LAN to Phone
An analyzer can only report on what it can see. If the analyzer, depending upon its configuration, is unable to monitor all four of these states in a single call, this will impact the reported metrics. As a result, the monitoring tools need visibility into each MedPro and C-LAN to report on a call.
Tags: avaya, avaya monitor, cisco, ip telephony, ipt, network instruments
May 31, 2008 at 7:50 am |
Actually, there is some very good tools from Avaya to help diagnose VoIP problems on the network. Avaya offers a software package called VMM (Voice Monitor Manager), which communicates with all the CLANS, MEDPROS and VoIP endpoints on your network to report back statistics, such as round-trip-delay, deviance-buffers (jitter), perceived link quality (MOS Score), among others. It writes all this data to a MS-SQL server which you can mine for reports, or you can use their front-end to view the results.
You can also use Avaya Site Administrator to see these same results on a case-by-case basis. Using the “list trace station” command, you will get back very detailed reporting of the call setup, media setup, media transmission, media tear-down, and the call-tear down. This software is included with each Avaya Communication Manager install (a similar tool is available for IP office, known as Phone Manager). This is the primary tool that a phone admin would use (as it is the same tool they use to admin stations).
Others tools, such as WireShare will give you excellent diag tools, and are OSS, and cross-phone-platform (as well as OS platform). They will show you visually what data is going over the wire, and in the case of a default Cisco or Asterisk install, you can even listen to the conversations (not in real-time however). WireShark needs to be placed in a portion of your network where your voice data would traverse (the Avaya tools above do not require this).
Hope this helps a bit! More information on these tools are available at the Avaya User’s Community Forums (http://www.aucommunity.com/)
June 4, 2008 at 10:01 am |
Really appreciated your comments on available Avaya tools and other monitoring applications. Both product sets, whether from Network Instruments or Avaya, have definite markets. It depends upon the type of organization and network we’re talking about.
Part of what spawned this post was the number of Avaya customers that have been purchasing our tools. A couple of things come to mind in terms of looking at why someone might look at Network Instruments in addition to the Avaya tools:
Integrated VoIP and Network Monitoring
Given VoIP’s sensitivity to interruptions from other applications, it’s important to have a complete view of all network traffic. Network Instruments solutions provide that complete view of all applications flowing across your entire network. So, from your web browser you could monitor VoIP, see MOS is decreasing, and immediately identify whether an unexpected bandwidth spike from another application caused the problem.
Handling Higher Network Speeds
Wireshark is a solid solution, but it does have limitations for larger organizations monitoring larger full-duplex gigabit and 10 Gigabit Ethernet networks. This is a part of what I meant by each product has its markets. Your network environment may dictate the monitoring solutions you use.
Post-Event Capture vs. Rewinding the Network
One of the newest developments in network troubleshooting has been the ability to store terabytes of network-level data for later replay and analysis called retrospective network analysis (RNA). Rather than having to wait for the problem to recur, network engineers can rewind the network and replay the event. In the same way that TiVo changed the way we watch TV, GigaStor and similar RNA products are changing troubleshooting. When time to resolution is critical, RNA offers significant time savings over traditional analysis tools by eliminating problem recreation.
Drilling Into Packets
Although Avaya offerings allow you to monitor statistics such as round-trip-delay, deviance-buffers (jitter), perceived link quality (MOS Score), among others, how do you proceed to troubleshooting when you do spot a potential performance problem? With Network Instruments solutions you can easily drill from a high-level statistical view down to the packet level for quick diagnosis. So upon seeing any type of call quality issues, you could immediately dive into the packets. You can also use experts to graphically view the network conversations to identify latency, see packets traveling across multiple network segments, replay the VoIP call, etc.
Reporting and Data Mining
Network Instruments reports can be viewed either from the console or web browser. VoIP statistics can be tracked on an aggregated or per-call basis. Data mining and drill down is seamless because it’s the same product. So there isn’t any use of an outside database or toggling between different tools. Not to mention hoping that the data same data captured/monitored by one solution was seen by the other.