Category:Cisco Systems -> Routing and Switching
SLA stands for Service License Agreement.
Multimedia Service Requirements:
| Traffic Type | Maximum Packet Loss | Maximum One-Way Latency | Maximum Jitter |
|---|---|---|---|
| VoIP | 1% | 150ms | 30ms |
| Interactive video | 0.05% | 150ms | 10ms |
| Streaming video | 0.1% | 1000ms | 100ms |
IP SLA measurement uses various operations and actively generated traffic probes to gather many types of measurement statistics, including the following:
- Network latency and response time
- Packet-loss statistics
- Network jitter and voice-quality scoring
- Statistical end-to-end matrix of performance information
- End-to-end network connectivity
Deploying IP SLA Measurements:
| _ | Data Traffic | VoIP | SLA Verification | Availability | Streaming Video |
|---|---|---|---|---|---|
| Requirement | Minimize delay, packet loss Verify QoS | Minimize delay, packet loss, jitter | Measure delay, packet loss, jitter One-way | Connectivity testing | Minimize delay, packet loss |
| IP SLA measurement | Jitter Packet loss Latency | Jitter Packet loss Latency MOS voice quality score | Jitter Packet loss Latency One-way Enhanced accuracy NTP | Connectivity tests to IP devices | Jitter Packet loss Latency |
More info: File:SLA.ppt
This is a functional diagram for IP SLA measurements:
For testing I took my old lab:
R1 will be the source router from which all the tests will be initiated. R4 will be a responder router.
SLA measurement for jitter requires a RESPONDER in the network. Responder configuration is really simple.
Configuration of R4 is as follows:
R4(config)#ip sla responder
R1 is the source router and its configuration is the following:
ip sla 10
udp-jitter 7.7.7.7 5000 source-ip 5.5.5.5 source-port 5000
frequency 10
ip sla schedule 10 life forever start-time now
R1#sh ip sla stat
Round Trip Time (RTT) for Index 10
Latest RTT: 77 milliseconds
Latest operation start time: *00:38:03.487 UTC Fri Mar 1 2002
Latest operation return code: OK
RTT Values:
Number Of RTT: 10 RTT Min/Avg/Max: 64/77/93 milliseconds
Latency one-way time:
Number of Latency one-way Samples: 0
Source to Destination Latency one way Min/Avg/Max: 0/0/0 milliseconds
Destination to Source Latency one way Min/Avg/Max: 0/0/0 milliseconds
Jitter Time:
Number of SD Jitter Samples: 9
Number of DS Jitter Samples: 9
Source to Destination Jitter Min/Avg/Max: 5/13/21 milliseconds
Destination to Source Jitter Min/Avg/Max: 1/4/8 milliseconds
Packet Loss Values:
Loss Source to Destination: 0 Loss Destination to Source: 0
Out Of Sequence: 0 Tail Drop: 0
Packet Late Arrival: 0 Packet Skipped: 0
Voice Score Values:
Calculated Planning Impairment Factor (ICPIF): 0
Mean Opinion Score (MOS): 0
Number of successes: 5
Number of failures: 0
Operation time to live: Forever
R4
R4#sh ip sla responder
IP SLAs Responder is: Enabled
Number of control message received: 145 Number of errors: 0
Recent sources:
5.5.5.5 [00:54:17.323 UTC Fri Mar 1 2002]
5.5.5.5 [00:54:07.299 UTC Fri Mar 1 2002]
5.5.5.5 [00:53:57.307 UTC Fri Mar 1 2002]
5.5.5.5 [00:53:47.335 UTC Fri Mar 1 2002]
5.5.5.5 [00:53:37.331 UTC Fri Mar 1 2002]
Recent error sources:
udpEcho Responder:
IP Address Port
Now let’s measure one-way time and round trip time (RTT)
R1
ip sla 20
icmp-echo 7.7.7.7
frequency 10
ip sla schedule 20 life forever start-time now
R1#sh ip sla stat
Round Trip Time (RTT) for Index 10
Latest RTT: 77 milliseconds
Latest operation start time: *00:39:43.495 UTC Fri Mar 1 2002
Latest operation return code: OK
RTT Values:
Number Of RTT: 10 RTT Min/Avg/Max: 61/77/96 milliseconds
Latency one-way time:
Number of Latency one-way Samples: 0
Source to Destination Latency one way Min/Avg/Max: 0/0/0 milliseconds // Nothing here because no NTP sync configured
Destination to Source Latency one way Min/Avg/Max: 0/0/0 milliseconds // Nothing here because no NTP sync configured
Jitter Time:
Number of SD Jitter Samples: 9
Number of DS Jitter Samples: 9
Source to Destination Jitter Min/Avg/Max: 7/13/24 milliseconds
Destination to Source Jitter Min/Avg/Max: 0/9/26 milliseconds
Packet Loss Values:
Loss Source to Destination: 0 Loss Destination to Source: 0
Out Of Sequence: 0 Tail Drop: 0
Packet Late Arrival: 0 Packet Skipped: 0
Voice Score Values:
Calculated Planning Impairment Factor (ICPIF): 0
Mean Opinion Score (MOS): 0
Number of successes: 14
Number of failures: 0
Operation time to live: Forever
Round Trip Time (RTT) for Index 20
Latest RTT: 107 milliseconds
Latest operation start time: *00:39:41.531 UTC Fri Mar 1 2002
Latest operation return code: OK
Number of successes: 5
Number of failures: 0
Operation time to live: Forever
IP SLA for Testing VoIP Channel Quality
Defines end-to-end (one way) delay, Jitter, Packet loss. By these parameters Service Assurance Agent (Cisco SAA) computes MOS and ICPIF and transfers data to snmp server.
Side A:
ip sla 10
udp-jitter 10.x.y.3 20001 source-ip 10.x.y.1 codec g711ulaw codec-size 20
tos 184
frequency 300
ip sla schedule 10 life forever start-time now
!
access-list 5 permit 10.x.y.50
snmp-server community cmonitor RO 5
snmp-server ifindex persist
Side B:
ip sla responder
access-list 5 permit 10.x.y.50
snmp-server community cmonitor RO 5
snmp-server ifindex persist
Show commands:
show ip sla statistics 10
show snmp mib ifmib ifindex
To monitor and analyse data one can use, eg PRTG, by navigating to VoIP and Qos > Cisco IP SLA
