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User Guide for the Cisco Network Analysis Module (NAM) Traffic Analyzer, 5.0
OL-22617-01
Chapter 2 Setting Up The NAM Traffic Analyzer
Default Functions
Application Response Time Metrics
The NAM Traffic Analyzer software provides response time measurements and various
user-experience-related metrics, which are computed by monitoring and time-stamping packets sent
from the user to the server providing services.
These Application Response Time Metrics are available to view under the menu Analyze > Response
Time. You can view response times for applications, networks, servers, and clients.
After the NAM Traffic Analyzer is started, these metrics will begin to populate.
Voice Signaling/RTP Stream Monitoring
After the NAM Traffic Analyzer is started, voice signaling and RTP stream traffic will automatically
start being monitored. The NAM enables you to monitor all RTP stream traffic among all SPANed traffic,
without having to know the signalling traffic used in negotiating the RTP channels. When RTP Stream
Monitoring is enabled, the NAM:
• Identifies all RTP streams among the SPANed traffic
• Monitors the identified RTP traffic
• Sends syslog, trap, e-mail, and trigger captures for RTP streams that violate stream statistics
thresholds on the following metrics:
–
Number of Consecutive Packet Loss
Each RTP packet has an RTP header that contains a sequence number. The sequence number
increments by one for each RTP packet received in the same RTP stream. A gap in the sequence
numbers identifies a packet loss. If the gap in sequence numbers jump is more than the
threshold, the NAM raises an alarm condition.
–
Packet Loss percent
There are two types of percent packet loss percent: Adjusted Packet Loss and Actual Packet
Loss. Actual Packet Loss indicates expected packets that never appear in the NAM. Adjusted
Packet Loss includes actual packets lost and packets that arrive with large delay beyond the
expected buffer capacity of the endpoint.
–
Jitter: Packets delay compare to the expected receiving time
–
Concealment Seconds: Seconds in which there is one or more packet lost
–
Severe Concealment Seconds: Seconds in which there is more than 5% of packet lost
You can set up thresholds at Setup > Alarms > Thresholds.
You can define filter entries to narrow down to the subset of RTP streams so the NAM monitors only
those RTP streams matching the filter criteria.
To verify that the voice signaling/RTP traffic has begun, choose Analyze > Media > RTP Streams or
Analyze > Media > Voice Call Statistics.