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Jobin Varghese
Beginner

Implement QoS on MPLS

Hi

I want to implement QoS for video conferencing over our MPLS links. The video conferencing makes use of Microsoft Lync and Polycom devices.

Could anyone provide any sample configurations as to how to go about with the configuration. 

5 REPLIES 5
driss JABBAR
Beginner

Hello Jobin,

There are three Qos Model in MPLS network:

Uniform mode:

DiffServ Tunneling Uniform Mode has only one layer of QoS, which reaches end-to-end. The ingress PE router  copies the DSCP from the incoming IP packet into the MPLS EXP bits of the imposed labels. As the EXP bits travel through the core, they may or may not be modified by intermediate P routers. In this example, P router P1 modifies the EXP bits of the top label. At the egress P router  we copy the EXP bits to the EXP bits of the newly exposed label after the PHP (Penultimate-Hop-Pop).Finally at the egress PE router  we then copy the EXP bits to the DSCP bits of the newly exposed IP packet.

Long Pipe:

Diffserv Tunneling Pipe Mode uses two layers of QoS:

  1. An underlying QoS for the data, which remains unchanged when traversing the core.

  2. A per-core QoS, which is separate from that of the underlying IP packets. This per-core QoS PHB remains transparent to end users.

When a packet reaches the edge of the MPLS core, the egress PE router  classifies the newly exposed IP packets for outbound queuing based on the MPLS PHB from the EXP bits of the recently removed label.

Short Pipe:

Diffserv Tunneling Short-pipe Mode uses the same rules and techniques across the core. The difference is at the egress PE router —you classify the newly exposed IP packets for outbound queuing based on the IP PHB from the DSCP value of this IP packet.

If you manage the MPLS network than the uniform mode is the appropriate mode for you.

have a look at this for the configuration: 

http://www.cisco.com/c/en/us/support/docs/multiprotocol-label-switching-mpls/mpls/47815-diffserv-tunnel.html#uniform

hope this helps

Joseph W. Doherty
Hall of Fame Expert

". . . over our MPLS links."

So you're running MPLS natively, or are you running over some service provider network that uses MPLS?

Over service providers.

Ok, then assuming you're not doing actual MPLS with your SP, you might ask if they support any QoS.  Often SPs running over MPLS offer some QoS support, sometimes at no additional cost, sometimes with an additional cost.  When they provide it, it's usually based on DSCP marked traffic obtaining different class treatments.

Other than using DSCP markings that work with your SP's QoS model, you can also do your own QoS up to, and including, the SP hand-off.  If you're not logically doing multi-point across your SP, you may only need your own QoS.  Even with multi-point, you can often manage your bandwidth with shapers and use QoS with them.  This too allows ful QoS management, but it "wastes" SP bandwidth (that you're paying for).

What kind of platform are you using that has the SP hand-offs?

driss JABBAR
Beginner

Hello Jobin,

There are three Qos Model in MPLS network:

Uniform mode:

DiffServ Tunneling Uniform Mode has only one layer of QoS, which reaches end-to-end. The ingress PE router  copies the DSCP from the incoming IP packet into the MPLS EXP bits of the imposed labels. As the EXP bits travel through the core, they may or may not be modified by intermediate P routers. In this example, P router P1 modifies the EXP bits of the top label. At the egress P router  we copy the EXP bits to the EXP bits of the newly exposed label after the PHP (Penultimate-Hop-Pop).Finally at the egress PE router  we then copy the EXP bits to the DSCP bits of the newly exposed IP packet.

Long Pipe:

Diffserv Tunneling Pipe Mode uses two layers of QoS:

  1. An underlying QoS for the data, which remains unchanged when traversing the core.

  2. A per-core QoS, which is separate from that of the underlying IP packets. This per-core QoS PHB remains transparent to end users.

When a packet reaches the edge of the MPLS core, the egress PE router  classifies the newly exposed IP packets for outbound queuing based on the MPLS PHB from the EXP bits of the recently removed label.

Short Pipe:

Diffserv Tunneling Short-pipe Mode uses the same rules and techniques across the core. The difference is at the egress PE router —you classify the newly exposed IP packets for outbound queuing based on the IP PHB from the DSCP value of this IP packet.

If you manage the MPLS network than the uniform mode is the appropriate mode for you.

have a look at this for the configuration: 

http://www.cisco.com/c/en/us/support/docs/multiprotocol-label-switching-...

hope this helps