This feature performs ‘Time To Live’ (TTL) processing for Multi-Protocol Label Switching (MPLS) packets. The TTL processing is decided by the model chosen by you. This feature will provide TTL processing of MPLS packets on ingress, egress, and intermediate routers. TTL processing is compliant with RFC 3443. The details of TTL processing vary with the tunnel model that is configured for TTL processing.

The incoming and outgoing TTL of the packet is determined by the configured tunnel model. This feature implements different rules for processing of the TTL on I-LER, LSR, E-LER:

Short Pipe model is a slight variation of the Pipe Model and is used to differentiate between different egress forwarding and QoS treatments.Short Pipe Model is utilized when the customer and service provider are in different DiffServ domains. Hence the models provided to the users are uniform, Short Pipe, and Pipe.

In OcNOS, Uniform and Pipe model are present. Uniform model is taken by default. The Pipe Model for TTL is can be being used in multiple networks and is provided as a configurable option. This chapter shows Uniform, Short pipe, and Pipe models as per RFC 3443.