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Defining CoS Rewrite Rules

 

Edge switches might need to change the class-of-service (CoS) settings of the packets. You can configure rewrite rules to alter code point bit values in outgoing packets on the outbound interfaces of a switch so that the CoS treatment matches the policies of a targeted peer. Policy matching allows the downstream routing platform or switch in a neighboring network to classify each packet into the appropriate service group.

To configure a CoS rewrite rule, create the rule by giving it a name and associating it with a forwarding class, loss priority, and code point. This creates a rewrite table. After the rewrite rule is created, enable it on an interface (EXP rewrite rules can only be enabled on family mpls logical interfaces, not on physical interfaces). You can also apply an existing rewrite rule on an interface.

Note

OCX Series switches do not support MPLS, so they do not support EXP rewrite rules.

Note

On each physical interface, either all forwarding classes that are being used on the interface must have rewrite rules configured, or no forwarding classes that are being used on the interface can have rewrite rules configured. On any physical port, do not mix forwarding classes with rewrite rules and forwarding classes without rewrite rules.

Note

To replace an existing rewrite rule on the interface with a new rewrite rule of the same type, first explicitly remove the existing rewrite rule and then apply the new rule.

Note

For packets that carry both an inner VLAN tag and an outer VLAN tag, the rewrite rule rewrites only the outer VLAN tag.

To create rewrite rules and enable them on interfaces:

  • To create an 802.1p rewrite rule named customup-rw in the rewrite table for all Layer 2 interfaces:

    [edit class-of-service rewrite-rules]

    user@switch# set ieee-802.1 customup-rw forwarding-class be loss-priority low code-point 000

    user@switch# set ieee-802.1 customup-rw forwarding-class be loss-priority high code-point 001

    user@switch# set ieee-802.1 customup-rw forwarding-class be loss-priority low code-point 010

    user@switch# set ieee-802.1 customup-rw forwarding-class fcoe loss-priority low code-point 011

    user@switch# set ieee-802.1 customup-rw forwarding-class ef-no-loss loss-priority low code-point 100

    user@switch# set ieee-802.1 customup-rw forwarding-class ef-no-loss loss-priority high code-point 101

    user@switch# set ieee-802.1 customup-rw forwarding-class nc loss-priority low code-point 110

    user@switch# set ieee-802.1 customup-rw forwarding-class nc loss-priority high code-point 111
  • To enable an 802.1p rewrite rule named customup-rw on a Layer 2 interface:

    [edit]

    user@switch# set class-of-service interfaces xe-0/0/7 unit 0 rewrite-rules ieee-802.1 customup-rw
    Note

    All forwarding classes assigned to port xe-0/0/7 must have rewrite rules. Do not mix forwarding classes that have rewrite rules with forwarding classes that do not have rewrite rules on the same physical interface.

  • To enable an 802.1p rewrite rule named customup-rw on all 10-Gigabit Ethernet interfaces on the switch, use wildcards for the interface name and logical interface (unit) number:

    [edit]

    user@switch# set class-of-service interfaces xe-* unit * rewrite-rules customup-rw

    Note

    In this case, all forwarding classes assigned to all 10-Gigabit Ethernet ports must have rewrite rules. Do not mix forwarding classes that have rewrite rules with forwarding classes that do not have rewrite rules on the same physical interface.