Checking for QoS?

Unanswered Question
Jan 5th, 2009

I've been tasked with checking our existing CCM 5.1 system to see if our VAR implemented any type of QoS at all.

I've been going through some packet captures of calls, but I'm not really sure what to look for. I know there's multiple methods and ways to do it, but can anyone give me some pointers on what I can look at to even tell if it's implemented at all, and how?

Thanks in advance!

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Nicholas Matthews Mon, 01/05/2009 - 13:11

A few things you can do:

Find out where your WAN circuits are. Don't know? Do a traceroute and telnet to each device, and use show ip route and show run interface to find out. Look for a WAN interface with a policy map. After you find out which interface the packet is going out of on each hop, do a 'show policy-map interface' and see if the selected interface has QoS applied.

Also, IP SLA is your friend. Here's a little bit I configured/tested:

Sending side:

ip sla monitor 3

type jitter dest-ipaddr 172.16.1.2 dest-port 16384 codec g711ulaw codec-numpackets 30

tos 184

frequency 10

ip sla monitor schedule 3 start-time now

ip sla monitor 4

type jitter dest-ipaddr 172.16.35.5 dest-port 16386 codec g711ulaw codec-numpackets 20

tos 184

frequency 5

ip sla monitor schedule 4 start-time now

Receiving side:

ip sla monitor responder

R3#sh ip sla moni stat

Round trip time (RTT) Index 3

Latest RTT: 54 ms

Latest operation start time: 00:11:46.823 UTC Tue Jan 1 2008

Latest operation return code: OK

RTT Values

Number Of RTT: 13

RTT Min/Avg/Max: 108/124/153 ms

Latency one-way time milliseconds

Number of one-way Samples: 0

Source to Destination one way Min/Avg/Max: 0/0/0 ms

Destination to Source one way Min/Avg/Max: 0/0/0 ms

Jitter time milliseconds

Number of Jitter Samples: 7

Source to Destination Jitter Min/Avg/Max: 5/6/7 ms

Destination to Source Jitter Min/Avg/Max: 1/1/1 ms

Packet Loss Values

Loss Source to Destination: 17 Loss Destination to Source: 0

Out Of Sequence: 0 Tail Drop: 0 Packet Late Arrival: 0

Voice Score Values

Calculated Planning Impairment Factor (ICPIF): 25

Mean Opinion Score (MOS): 3.50

Number of successes: 20

Number of failures: 0

Operation time to live: 3393 sec

Round trip time (RTT) Index 4

Latest RTT: 2 ms

Latest operation start time: 00:12:01.167 UTC Tue Jan 1 2008

Latest operation return code: OK

RTT Values

Number Of RTT: 20

RTT Min/Avg/Max: 2/2/2 ms

Latency one-way time milliseconds

Number of one-way Samples: 0

Source to Destination one way Min/Avg/Max: 0/0/0 ms

Destination to Source one way Min/Avg/Max: 0/0/0 ms

Jitter time milliseconds

Number of Jitter Samples: 19

Source to Destination Jitter Min/Avg/Max: 0/0/0 ms

Destination to Source Jitter Min/Avg/Max: 0/0/0 ms

Packet Loss Values

Loss Source to Destination: 0 Loss Destination to Source: 0

Out Of Sequence: 0 Tail Drop: 0 Packet Late Arrival: 0

Voice Score Values

Calculated Planning Impairment Factor (ICPIF): 1

Mean Opinion Score (MOS): 4.34

Number of successes: 6

Number of failures: 0

Operation time to live: 3570 sec

hth,

nick

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