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Bronze

qualtiy of service resolution

hey,

have had a QOS issue for the past 3 mnths and didnt have a clue as to how to resolve. after much research, trial and error, i think i finally got it. (almost).

turned on vad on dial-peers, comfort noise, and vad in ccm. issues were hissing static for calls going out, and coming in. all issues now resolved, except, calls coming in, have an initial cut in speech then levels off fine with intermittent cuts then and again.

any ideas as to how i might be able to resolve this final issue.

playout delay? music on hold?...

3 REPLIES

Re: qualtiy of service resolution

Hmm.

Sounds like over-subscribed links leading to delay and excessive echo cancellation. Enabling VAD reduces bandwidth requirements, and may have released some bandwidth, thus providing some relief. But as you said, VAD inherently leads to clipping. Many environments disable VAD since the clipping can be quite annoying.

How do you handle QoS along the path from gateway to phone?

What were the policies applied?

Any previously conjested link? What did "show policy-map interface" output for congested interfaces tell you about dropped & queued packets?

Have you considered the Enterprise QoS SRND at:

http://www.cisco.com/go/srnd

or

http://www.cisco.com/application/pdf/en/us/guest/netsol/ns432/c649/ccmigration_09186a008049b062.pdf

Like any tech doc, its a boring read. But there's lot's of really, really good information in there!

Michael

Bronze

Re: qualtiy of service resolution

hey,

have been posting about this for sometime now. the lines coming into the call center are 4 pstn lines. there are only 5 7940 ip phones at head office utilising these lines. the router has and fa0/0 connected to the firewall, then we have another router connected to the firewall linking the voice to the data network. (the solution has many flaws), we have no QOS on the switches (dell). the switch story is very long, basically, just before we put in IPT, he bought dell switches, when we came in we recommeded Cisco switches, but, he is in a bind at the moment so we are trying to work with what we have. we have no dropped packets at this point in time. calls withing network locations as well as calls going out are PERFECT agents are very pleased, i called INTO the call center and i have noticed the slight clipping.

im going to take a read now and see if anything pops up.

here is the policy map output i just did

FastEthernet0/0

Service-policy input: Lan

Class-map: voice (match-any)

4449180 packets, 949365749 bytes

5 minute offered rate 159000 bps, drop rate 0 bps

Match: access-group 102

4432542 packets, 947915758 bytes

5 minute rate 159000 bps

Match: ip dscp ef (46)

0 packets, 0 bytes

5 minute rate 0 bps

Match: ip dscp cs5 (40)

0 packets, 0 bytes

5 minute rate 0 bps

Match: access-group 120

16638 packets, 1449991 bytes

5 minute rate 0 bps

QoS Set

precedence 5

Packets marked 4449180

Class-map: video (match-any)

0 packets, 0 bytes

5 minute offered rate 0 bps, drop rate 0 bps

Match: ip dscp af41 (34)

0 packets, 0 bytes

5 minute rate 0 bps

Match: ip dscp cs4 (32)

0 packets, 0 bytes

5 minute rate 0 bps

QoS Set

precedence 4

Packets marked 0

Class-map: voice-sig (match-any)

660055 packets, 58408121 bytes

5 minute offered rate 1000 bps, drop rate 0 bps

Match: access-group 103

131481 packets, 9538614 bytes

5 minute rate 0 bps

Match: ip dscp af31 (26)

4465 packets, 1102584 bytes

5 minute rate 0 bps

Match: ip dscp cs3 (24)

524109 packets, 47766923 bytes

5 minute rate 1000 bps

Match: access-group 120

0 packets, 0 bytes

5 minute rate 0 bps

QoS Set

precedence 3

Packets marked 660079

Class-map: class-default (match-any)

3859840 packets, 2018612493 bytes

5 minute offered rate 66000 bps, drop rate 0 bps

Match: any

Bronze

Re: qualtiy of service resolution

here is an attacchement for a currently active set of calls.

strangely enough, i have one agent that says that her phone logs her out intermittently. i have modified the config to force login even though calls are missed therefore they are always supposed to be logged in. that works fine for all other phones. what i noticed is that the phone loses conencction with ccm for a split second, causing the issue. i saw a bug related to tcp session loss. im thinking that might be the cause of her issue.

(i know, im throwing a lot of different stuff into the mix here)

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