Bandwidth Question

Unanswered Question
Mar 1st, 2010
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Hello guyz! need some expertise advice


I have 2 routers setup


connected via s0/3/0


ospf running


1 cipc phone on R1


Analogue phone R2


dial peers setup all fine


Codec = g711a


Bandwidth = 128

DCE = 128000


No QoS


Very basic setup...


Theory 1 G711a phone call = 95.2 kbps (Correct me if I'm wrong)


I call R2 from R1, one voice call and I get quality problems


I have setup IP SLA to monitor the values


MOS = 2.03


I have checked cables, changed cables, used different routers and they all give me the same MOS value 1.97 - 2.08


What can be the problem? because there's still 25% available bandwidth (95.2/128 = 74%)- MOS values should still be higher than 2


Please help!

Thanks in advance

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david-lima Mon, 03/01/2010 - 10:52
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Hi, check that you have enabled this commands on your routers:

1. check connectivity first

2. configure "h323-gateway voip bind srcaddr ip address" on the interface

3. configure "voice rtp send-recv"


hth

David

JDMJeffy84 Mon, 03/01/2010 - 12:23
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Hi David,


Connectivity is ok


the 2 commands, what do they do (in short?)


I will try those 2 commands out later


Just puzzled how 1 g711 call will cause jitter, packet loss etc on a 128 kbps serial link... =[

paolo bevilacqua Mon, 03/01/2010 - 15:06
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If you click the "?" twice button on IPCP, does it show packet loss ?

JDMJeffy84 Mon, 03/01/2010 - 15:26
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Hi p.bevilacqua,


Sorry if I sound 'noob' like...


What is ICPC?


Only ? I know of is checking syntax or command in cisco CLI

JDMJeffy84 Wed, 03/03/2010 - 13:19
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yes it does, packet loss increases by ~30 every sec


I repeated the test with:


2 g711a calls - average mos ~ 1.86
3 g711a calls - average mos ~ 1.76
4 g711a calls - average mos ~ 1.67


Over 128kbps bandwidth


Still i find these results strange

JDMJeffy84 Mon, 03/08/2010 - 07:21
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Ok guyz I found the problem...


I left IP SLA config as default


ip sla 1
udp-jitter 1.1.1.1 2222 codec g711a

freq 5
tos 184


With some help from a techy, looked into the config and bandwidth...


sh ip sla conf (Cisco default config of other parameters)


no of packets 1000

packet size 172


So 1 g711 call = 95 kbps + this ip sla traffic, will defo mess up my results!!!


every 5 sec sending 1000 packets size of 172 bytes!


I'm not sure how to work out the ip sla traffic badwidth, unless u guyz can explain!



But yes i changed the no of packets to 100


and size to 100


I get the result!



2nd Q.


What parameters does the Industry use? If left at default its going to screw up the results


Too low the packets will get through no problem!

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