VoIP Performance Management and Optimization: Managing VoIP Networks

Chapter Description

To ensure voice quality and to optimize media delivery over the IP, it is crucial to properly plan, design, implement, and manage the underlying network. This chapter discusses what are the best practices for planning media deployment over IP networks.

Alarm and Event Audit and Correlation

Root cause analysis (RCA) is key to incident management. RCA can be accelerated by following a steady alarm and event analysis practice. The practice can be developed through following basic exercise:

• Have a vigorous exercise of understanding the alarm and alarm groupings for all the network elements. As a result a key alarm summary list should be produced for all the products.
• A periodic collection of alarm history should be introduced then monitored actively through a Dashboard.
• The Dashboard should be used for history trending of alarms by market and functional groups. As a example two functional groups of SIP and PSTN related alarms should have their own visual mentoring groups.
• In a VOIP network, the VOICE switch (or corresponding EMS), sees all the protocol and most NE reported anomalies, It can be a good starting point for creating an alarm summary report.

The figure 6-5 shows a summary table of alarms for a particular customer site. The table has been generated off the alarm history report for CISCO BTS 10200. The table is periodically generated for many customer sites. It allows for identifying the hot spots and infrequent anomalies.

The figure shows the general group buckets and the detailed breakdown of the alarm frequency within the groups.

The most prevalent alarm buckets surface up. The periodic report can be easily used to first identify the problem, then the results be fed into the systemic RCA. In the case of Table 6-8 we clearly see the signaling alarms at the top, after analyzing the report, the alarms like “Trunk remotely blocked”, were ignored in this case, due to large number trunks were being turned-up and were down. But other alarms within the same category and other categories also need to be looked at for rooting out system issues.

Summary Alarm Table from CISCO Softswitch

Alarm Count	Alarm Group Type	Alarm Explanation
1	CALLP	Country Code Dialing Plan Error
1	DATABASE	EMS database alert.log alerts.
1	OSS	SNMP Authentication error
1	SIGNALING	SS7 Message Decoding Failure
1	SIGNALING	Unanswered REL
2	BILLING	FTP/SFTP transfer failed
2	DATABASE	Daily database backup completed successfully
2	SIGNALING	AGGR Connection Down
2	SIGNALING	Feature Server is not up or is not responding to Call Agent
2	SIGNALING	Continuity Recheck Successful
3	SIGNALING	AGGR Gate Set Failed
3	SIGNALING	Continuity Recheck is performed on specified CIC
6	SIGNALING	RLC received in response to RSC message on the specified CIC
10	AUDIT	Start or Stop of SS7-CIC audit
11	CALLP	No Route Available for Carrier Dialed
14	DATABASE	There are errors in EMS database DefError queue
27	MAINTENANCE	Admin State Change Failure
56	MAINTENANCE	Admin State Change Successful with Warning
76	AUDIT	Call exceeds a long-duration threshold
112	SIGNALING	Continuity Recheck Failed
215	SIGNALING	Media gateway/termination down
379	MAINTENANCE	Admin State Change
469	SIGNALING	Timeout on Remote Instance
803	CALLP	Invalid Call
981	SIGNALING	Unexpected Message for the Call State is received : Clear Ca
1166	CALLP	Call Failure
1194	SIGNALING	COT message received on the specified CIC
1267	BILLING	Message content error
1391	SIGNALING	General MGCP Signaling Error between MGW and CA.
5257	SIGNALING	Trunk locally blocked
5495	SIGNALING	Trunk remotely blocked
1391	SIGNALING	General MGCP Signaling Error between MGW and CA.
5257	SIGNALING	Trunk locally blocked

Thus the results are obvious of performing these audits on a periodic basis and analyzing them at the same time through a dashboard. The trouble segments surface up, and thus can be prioritized for resolution.