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Hierarchy Level


Force host-injected control packets to follow the transit path. Host-injected control traffic reaches the GRE tunnel interface queues at the PFE when the control session is over the GRE tunnel interface. This includes control protocols OSPF, BGP, PIM, RSVP, LDP, OAM, BFD and MSDP.

Injection of control traffic ensures that the kernel includes the interface ID of the GRE logical interface and the unicast next-hop ID of the corresponding GRE physical interface along with the packet that is injected into the PFE. PFE code uses the logical interface ID and next-hop ID information to forward the packet. GRE encapsulation occurs at the PFE level and the packet gets looped back over the GRE tunnel after being subjected to CoS treatment over the GRE interface queues. The looped back packet is subjected to a second lookup and is then forwarded over the egress physical interface.

Support for control traffic to travel over the GRE tunnel with CoS intact means the copy-tos-to-outer-ip-header statement cannot be used. Use the copy-tos-to-outer-ip-header-transit configuration statement instead. With this statement, all transit packets on the GRE tunnel logical interface have the TOS copied to the outer header.

To enable this feature, configure the force-control-packets-on-transit-path statement on the GRE tunnel logical interface. For example:

This example enables Layer 2.5 injection of control protocols on the GRE tunnel gr-4/0/10 unit 0 only.

This feature is supported on the MX204 and the MX NG MPCs (MPC2E-NG and MPC3E-NG).

Required Privilege Level


Release Information

Statement introduced in Junos OS Release 20.1R1.