Subject: [mpls] MPLS To Carry Voice Traffic

From: mahmed <[email-masked]>
Date: Fri, 3 Sep 2004 17:51:46 -0400

Dear Sir/Madam,

I have a question, regarding the voice over MPLS backbone performance?

Currently, Is there a guarantee for the voice quality of services to be carried over MPLS backbone,

As an example, if a mobile operator would like to have MPLS technology to be used in his backbone to carry voice traffic , where the voice traffic is much higher than data traffic, In such case , what shall be the QoS of voice traffic ? and If the QoS for voice traffic is granted , do you have  a list of GSM operators deployed MPLS technology to carry voice traffic now.

Best Regards,

Medhat Ahmed

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From: "Francois Le Faucheur \(flefauch\)" <[email-masked]>
Date: Tue, 7 Sep 2004 09:41:08 +0200

Medhat,
 
>> > 
>> > 
>> >      Currently, Is there a guarantee for the voice quality of
>> >      services to be carried over MPLS backbone,
>> > 

As has been described in earlier messages, two common approaches are:
	- Diffserv + Capacity Planning: Diffserv is used to schedule
Voice separately. Link size as well as Voice queue service rate are
dimensioned based on expected traffic.
	- Diffserv + Capacity Planning + Call-Control-based CAC: same as
previous, and in addition the Voice Call Control performs some Call
Admission Control and limits the maximum amount of calls that can be
established (to avoid exceptional peaks in voice load that the network
is not dimensioned to cope with).

The IETF is also standardizing a mechanisms supporting large scale
admission control over MPLS TE tunnels. This mechanism allows a third
approach which is:
	- Diffserv + Capacity Planning + Network-based CAC: Again,
Diffserv is used to schedule Voice separately and Link size as well as
Voice queue service rate are dimensioned based on expected traffic. But
this time in-band signalling is used to perform explicit CAC of voice
calls over the current network resources. Because the CAC mechanim
allows multiple levels of aggregation (eg at the MGW level and at the
MPLS TE Tunnel Head-end), it is very scalable. Because it relies on
explicit in-band signalling, this mechanisms can ensure absolute QoS
guarantees to the admitted voice traffic.
Details of this CAC mechanism can be found in
"draft-lefaucheur-rsvp-dste-00.txt" which was presented in the TSVWG in
San Diego. Feedback is welcome.

Cheers

Francois

>> > 
>> >      As an example, if a mobile operator would like to have MPLS
>> >      technology to be used in his backbone to carry voice traffic
>> >      , where the voice traffic is much higher than data traffic,
>> >      In such case , what shall be the QoS of voice traffic ? and
>> >      If the QoS for voice traffic is granted , do you have  a
>> >      list of GSM operators deployed MPLS technology to carry
>> >      voice traffic now.
>> > 
>> > 
>> > 
>> >      Best Regards,
>> > 
>> >      Medhat Ahmed