Rewrite the EXP Bits of All Three Labels of an Outgoing Packet

In interprovider, carrier-of-carrier, and complex traffic engineering scenarios, it is sometimes necessary to push three labels on the next hop, using a swap-push-push or triple-push operation.

By default, on M-Series routing platforms except the M320, the top MPLS EXP label of an outgoing packet is not rewritten when you configure swap-push-push and triple-push operations. You can rewrite the EXP bits of all three labels of an outgoing packet, thereby maintaining the CoS of an incoming MPLS or non-MPLS packet.

To push three labels on incoming MPLS packets, include the swap-push-push default statement at the [edit class-of-service interfaces interface-name unit logical-unit-number rewrite-rules] hierarchy level:

[edit class-of-service interfaces interface-name unit logical-unit-number 
rewrite-rules]

exp-swap-push-push default;

To push three labels on incoming non-MPLS packets, include the push-push-push default statement at the [edit class-of-service interfaces interface-name unit logical-unit-number rewrite-rules] hierarchy level:

[edit class-of-service interfaces interface-name unit logical-unit-number 
rewrite-rules]

exp-push-push-push default;

For more information about how to configure statements at the [edit class-of-service] hierarchy level, see the JUNOS Network Interfaces and Class of Service Configuration Guide manual.