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Configuring CoS on an MPLS Provider Edge Switch Using Circuit Cross-Connect


You can use class of service (CoS) within MPLS networks to prioritize certain types of traffic during periods of congestion. This topic describes configuring CoS components on a provider edge (PE) switch that is using MPLS over circuit-cross connect (CCC).


On EX Series switches other than EX8200 switches, if you are using MPLS over CCC, you can use only one DSCP or IP precedence classifier and only one IEEE 802.1p classifier on the CCC interfaces.

This procedure is for creating a custom DSCP classifier and a custom EXP rewrite rule on the ingress PE. It also includes enabling a policer on the label-switched path (LSP) of the ingress PE to ensure that the amount of traffic forwarded through the LSP never exceeds the requested bandwidth allocation.

This topic includes:

Configuring CoS

To configure CoS on a provider edge switch:

  1. Import the default DSCP classifier classes to the custom DSCP classifier that you are creating:
    [edit class-of-service]

    user@switch# set classifiers dscp classifier-nameimport default
  2. Add the expedited-forwarding class to this custom DSCP classifier, specifying a loss priority and code point:
    [edit class-of-service]

    user@switch# set classifiers dscp classifier-name forwarding-class forwarding-class loss-priority loss-priority code-points code-point
  3. Specify the values for the custom EXP rewrite rule, e1:
    [edit class-of-service]

    user@switch# set rewrite-rules exp e1 forwarding-class forwarding-class loss-priority loss-priority code-point code-point
  4. Bind the DSCP classifier to the CCC interface:
    [edit ]

    user@switch# set class-of-service interfaces interface unit unit classifier classifier-name
  5. On EX8200 switches only, bind the custom EXP rewrite rule to the interface:
    [edit class-of-service]

    user@switch# set class-of-service interfaces interface unit unit rewrite-rules exp e1

Configuring an LSP Policer

To configure an LSP policer:


You cannot configure LSP policers on EX8200 switches. EX8200 switches do not support LSP policers.

  1. Specify the number of bits per second permitted, on average, for the policer, which will later be applied to the LSP:
    [edit firewall]

    set policer mypolicer if-exceeding bandwidth-limit 500m
  2. Specify the maximum size permitted for bursts of data that exceed the given bandwidth limit for this policer:
    [edit firewall policer]

    set mypolicer if-exceeding burst-size-limit 33553920
  3. Discard traffic that exceeds the rate limits for this policer:
    [edit firewall policer]

    set mypolicer then discard
  4. To reference the policer, configure a filter term that includes the policer action:
    [edit firewall]

    user@switch# set family any filter myfilter term t1 then policer mypolicer
  5. Apply the filter to the LSP:
    [edit protocols mpls]

    set label-switched-path lsp_to_pe2_ge1 policing filter myfilter

You can also configure schedulers and shapers as needed. See Defining CoS Schedulers and Scheduler Maps (CLI Procedure).