• Status: Solved
  • Priority: Medium
  • Security: Public
  • Views: 399
  • Last Modified:

VoIP is Choppy and Garbled

I have a network with Cisco 7960 VoIP Phones, Call manager 3.1 and the access switches are 3500 XL series switches. All my Voice Calls are Chopping up and I need some assistance. I believe it might be QoS however does anyone have any sugjestions to fix the choppiness?

IOS Version: c3500XL-c3h2s-mz.120-5.WC3b.bin

This is the configuration of my interfaces; please advise

interface FastEthernet0/2
 duplex full
 switchport trunk encapsulation dot1q
 switchport mode trunk
 switchport voice vlan 10
 switchport priority extend cos 0
 spanning-tree portfast
0
TAMSCODAN
Asked:
TAMSCODAN
  • 11
  • 10
1 Solution
 
mikecrCommented:
Do you have this problem with internal calls, external, or both? What type of phone connectivity do you have for VoIP? I.e., router with voice PRI, etc?
0
 
TAMSCODANAuthor Commented:
My internal calls work well however when making external calls it is hard to make out what the person is saying. I have a router that makes a Point to Point connetion via a Promina to another Router
0
 
mikecrCommented:
This is a quality of service problem between the two voice routers. Does any data accompany voice across those routers?
0
Technology Partners: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

 
TAMSCODANAuthor Commented:
I have them seperated into two VLANs. I do have a question about that also I notice in my switch config:

interface VLAN1
 ip address XXX.X.XXX.XX 255.255.255.128
 no ip directed-broadcast
 ip nat outside
 no ip route-cache
!
interface VLAN10
 ip address YYY.YY.Y.YY 255.255.255.0
 no ip directed-broadcast
 no ip route-cache
 shutdown

VLAN 10 is my Voice VLAN however in my config i see shutdown. In addition everytime i  do a no shut the config stays the same. Is this part of my problem?
0
 
mikecrCommented:
You need to have something plugged into VLAN10 for it to come up. It has to have an active link. That needs to be fixed first before you can do the QoS.
0
 
TAMSCODANAuthor Commented:
like what? my phones are on VLAN 10 plugged into a trunked interface that allows both vlans. so i am at a loss at the moment.
0
 
mikecrCommented:
Do you have any phones physically on the switch with their ports on VLAN10, or are they trunked to the switch on another VLAN and are accepting VLAN10 tag packets?
0
 
TAMSCODANAuthor Commented:
They are trunked to the switch.
0
 
mikecrCommented:
Create a loopback ethernet plug and plug it into a port on your switch. Assign that port to VLAN10 and then do a "no shut" on it to see if it comes up. You could plug a laptop or something into it as well for testing purposes. That is a routable vlan. Your phones should be getting an IP on the same subnet as that VLAN, correct?
0
 
TAMSCODANAuthor Commented:
Yes they are.
0
 
TAMSCODANAuthor Commented:
I put a sniffer on my network made a call and this is what i got.

|Time     | 10.14.0.9         | 10.0.100.122      | 10.14.0.117       |
|13.145   |         CRCX      |                   |                   |MGCP AALN/S1/SU0/0@MINI14_NOCVG200A Request
|         |(2427)   ------------------>  (2427)   |                   |
|16.163   |         CRCX      |                   |                   |MGCP AALN/S1/SU0/0@MINI14_NOCVG200A Request Duplicate
|         |(2427)   ------------------>  (2427)   |                   |
|17.468   |         200 (CRCX) SDP ( g711U g711A G.729a G.726-16 G...6-24 g721 g728 G)          |                   |MGCP AALN/S1/SU0/0@MINI14_NOCVG200A Response
|         |(2427)   <------------------  (2427)   |                   |
|17.470   |         NTFY ObsEvt:L/hd              |                   |MGCP AALN/S1/SU0/0@MINI14_NOCVG200A Request
|         |(2427)   <------------------  (2427)   |                   |
|17.471   |         200 (NTFY)|                   |                   |MGCP AALN/S1/SU0/0@MINI14_NOCVG200A Response
|         |(2427)   ------------------>  (2427)   |                   |
|17.472   |         NTFY ObsEvt:H/oc              |                   |MGCP AALN/S1/SU0/0@MINI14_NOCVG200A Request
|         |(2427)   <------------------  (2427)   |                   |
|17.473   |         200 (NTFY)|                   |                   |MGCP AALN/S1/SU0/0@MINI14_NOCVG200A Response
|         |(2427)   ------------------>  (2427)   |                   |
|17.484   |         MDCX      |                   |                   |MGCP AALN/S1/SU0/0@MINI14_NOCVG200A Request
|         |(2427)   ------------------>  (2427)   |                   |
|18.048   |         NTFY ObsEvt:L/hd              |                   |MGCP AALN/S1/SU0/0@MINI14_NOCVG200A Request Duplicate
|         |(2427)   <------------------  (2427)   |                   |
|18.050   |         200 (NTFY)|                   |                   |MGCP AALN/S1/SU0/0@MINI14_NOCVG200A Response Duplicate
|         |(2427)   ------------------>  (2427)   |                   |
|18.050   |         NTFY ObsEvt:H/oc              |                   |MGCP AALN/S1/SU0/0@MINI14_NOCVG200A Request Duplicate
|         |(2427)   <------------------  (2427)   |                   |
|18.050   |         200 (NTFY)|                   |                   |MGCP AALN/S1/SU0/0@MINI14_NOCVG200A Response Duplicate
|         |(2427)   ------------------>  (2427)   |                   |
|18.052   |         NTFY ObsEvt:L/hd              |                   |MGCP AALN/S1/SU0/0@MINI14_NOCVG200A Request Duplicate
|         |(2427)   <------------------  (2427)   |                   |
|18.053   |         200 (NTFY)|                   |                   |MGCP AALN/S1/SU0/0@MINI14_NOCVG200A Response Duplicate
|         |(2427)   ------------------>  (2427)   |                   |
|18.054   |         NTFY ObsEvt:H/oc              |                   |MGCP AALN/S1/SU0/0@MINI14_NOCVG200A Request Duplicate
|         |(2427)   <------------------  (2427)   |                   |
|18.054   |         200 (NTFY)|                   |                   |MGCP AALN/S1/SU0/0@MINI14_NOCVG200A Response Duplicate
|         |(2427)   ------------------>  (2427)   |                   |
|18.190   |         NTFY ObsEvt:H/oc              |                   |MGCP AALN/S1/SU0/0@MINI14_NOCVG200A Request
|         |(2427)   <------------------  (2427)   |                   |
|18.192   |         200 (NTFY)|                   |                   |MGCP AALN/S1/SU0/0@MINI14_NOCVG200A Response
|         |(2427)   ------------------>  (2427)   |                   |
|18.196   |         200 (MDCX) SDP ( G.729b)          |                   |MGCP AALN/S1/SU0/0@MINI14_NOCVG200A Response
|         |(2427)   <------------------  (2427)   |                   |
|18.198   |         MDCX SDP ( 105)               |                   |MGCP AALN/S1/SU0/0@MINI14_NOCVG200A Request
|         |(2427)   ------------------>  (2427)   |                   |
|18.231   |                   |         RTP (g729)                    |RTP Num packets:1455  Duration:29.080s ssrc:-1424454805
|         |                   |(16386)  <------------------  (24626)  |
|18.620   |         NTFY ObsEvt:H/oc              |                   |MGCP AALN/S1/SU0/0@MINI14_NOCVG200A Request Duplicate
|         |(2427)   <------------------  (2427)   |                   |
|18.622   |         200 (NTFY)|                   |                   |MGCP AALN/S1/SU0/0@MINI14_NOCVG200A Response Duplicate
|         |(2427)   ------------------>  (2427)   |                   |
|18.918   |         200 (MDCX)|                   |                   |MGCP AALN/S1/SU0/0@MINI14_NOCVG200A Response
|         |(2427)   <------------------  (2427)   |                   |
|18.919   |                   |         RTP (g729)                    |RTP Num packets:1187  Duration:29.146s ssrc:75719802
|         |                   |(16386)  ------------------>  (24626)  |
|47.328   |         MDCX      |                   |                   |MGCP AALN/S1/SU0/0@MINI14_NOCVG200A Request
|         |(2427)   ------------------>  (2427)   |                   |
|48.066   |         200 (MDCX)|                   |                   |MGCP AALN/S1/SU0/0@MINI14_NOCVG200A Response
|         |(2427)   <------------------  (2427)   |                   |
|48.070   |         DLCX      |                   |                   |MGCP AALN/S1/SU0/0@MINI14_NOCVG200A Request
|         |(2427)   ------------------>  (2427)   |                   |
|48.796   |         250 (DLCX)|                   |                   |MGCP AALN/S1/SU0/0@MINI14_NOCVG200A Response
|         |(2427)   <------------------  (2427)   |                   |
0
 
TAMSCODANAuthor Commented:
I dont know if that means anything to you but I have no clue right now
0
 
mikecrCommented:
Looks like MGCP talking to Cisco CallManager. Do a "show ip cef" on the switch and see if it's turned on. It should show you what looks like a routing table. Also, did you get the vlan to come up?
0
 
TAMSCODANAuthor Commented:
#show ip cef
%IPv4 CEF not running
0
 
mikecrCommented:
Turn on ip cef on the switch by logging in and from the configuration prompt, type "ip cef". This will turn on cef's fast switching protocol.
0
 
TAMSCODANAuthor Commented:
when i do that i just get an incomplete command however these are my options

(config)#ip cef ?
  accounting          Enable CEF accounting
  distributed         Distributed Cisco Express Forwarding
  linecard            CEF linecard commands
  load-sharing        Load sharing
  traffic-statistics  Enable collection of traffic statistics
0
 
TAMSCODANAuthor Commented:
ip cef is enabled on my router. THis is for the switch. I would have to enable routing on my swtich however it is not a layer 3 switch.
0
 
mikecrCommented:
It may not be supported on your model depending on IOS and age. Create a bogus vlan and go into it and type "ip route-cache cef" and see if it lets you do it.
0
 
mikecrCommented:
CEF is layer2.
0
 
TAMSCODANAuthor Commented:
according Oreilly Books CEF  is a layer 3 switching technology.  Boney J. CISCO IOS IN A NUTSHELL Second Edition (2005) Pg 490, Oreilly
0
 
mikecrCommented:
IT actually works at layer 2.
0

Featured Post

NEW Veeam Agent for Microsoft Windows

Backup and recover physical and cloud-based servers and workstations, as well as endpoint devices that belong to remote users. Avoid downtime and data loss quickly and easily for Windows-based physical or public cloud-based workloads!

  • 11
  • 10
Tackle projects and never again get stuck behind a technical roadblock.
Join Now