03-10-2007 02:24 AM - edited 03-03-2019 04:07 PM
I have 8 sites connected together over a full mesh MPLS.
One site has international connectivity where my VoIP gateway is located. It has 2 PRI lines terminated onto it.
Each site has a number of VoIP phones and they mainly use it for international calling. During Peak traffic the VoIP quality degrades.
Qos is configured on the LAN by trusting the DSCP values on the trunk. On the routers connecting to MPLS, the following QoS has been configured
class-map match-all voip
match ip precedence 5
class-map match-all signalling
match ip precedence 3
policy-map VOIP
class M6logserver
police 8000 conform-action transmit exceed-action drop
class voip
priority 1024
class signalling
priority 200
interface FastEthernet0/1
service-policy output VOIP
I do not see any drops on the policy-map interface
Is there a better way to configure the QoS
thanks in advance
03-10-2007 02:28 AM
03-10-2007 10:25 PM
Does your MPLS provider apply QOS to protect your voice traffic? If your routers are not dropping packets then it must be happening in the MPLS cloud.
I am wondering about 1024 for 46 voice channels. How full do the PRIs get? Assuming G729 you should allocate at least 26kb per call or 1196kb if there is any chance of filling both PRIs. Your signaling class does not need to be priority queued, just use bandwidth 200.
Another possibility is that the DSCP markings are getting overwritten to 0s before getting to your routers. Does the priority queue bandwidth (show policy-map interface) at site 4 match up with the number of active calls (sh voice call summ)on the voice gateway router? If you set the load interval to 30 it will track more closely. A Sniffer would also confirm the DSCP. It is pretty easy to misconfigure a switch and overwrite the DSCP values.
Dave
03-18-2007 06:32 AM
The MPLS provider is doing QoS on his cloud. Thats what they say.
On the LAN switches i am just trusting the DSCP on the lan switches (no marking or classification)
Sometimes during peak utilization, the latency from site1 to site 4 exceeds to 200ms and hence all international calls suffer.
Will it help if i create a seperate vlan for voice and mark the DSCP at the access and configure queuing.
03-18-2007 09:15 AM
Before configuring anything, check if you can have the voice traffic be marked EF at the source and sent unchanged to the provider.
You can also configure a SLA probe/ responder sending UDP / EF traffic and measure delay/jitter over time.
Once you have proof that the problem is in the cloud, call the provider and complain to them.
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