03-01-2010 05:46 AM - edited 03-17-2019 09:57 PM
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
03-01-2010 10:52 AM
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
03-01-2010 12:23 PM
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... =[
03-01-2010 03:06 PM
If you click the "?" twice button on IPCP, does it show packet loss ?
03-01-2010 03:26 PM
Hi p.bevilacqua,
Sorry if I sound 'noob' like...
What is ICPC?
Only ? I know of is checking syntax or command in cisco CLI
03-02-2010 04:21 AM
The cipc.
03-03-2010 01:19 PM
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
03-08-2010 07:21 AM
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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