Loop detection and avoidance for segment routed traffic engineered paths

One or more non-transitory tangible media that includes code for execution and when executed by a processor is operable to perform operations comprising:

• obtaining a packet of a traffic flow at an ingress node of a communications network;
• calculating a shortest path between a beginning of a current segment of a tunnel associated with a first segment-switched path and an end of the current segment;
• routing the packet to an egress node of the communications network via either the first segment-switched path or a second segment-switched path different than the first segment-switched path depending on whether the packet was obtained from a first node external to the communications network or from a second node internal to the communications network;
• determining whether or not the shortest path traverses a head end of the tunnel;
• and
• using either the tunnel or a different tunnel to implement the first segment-switched path depending on whether the shortest path traverses the head end of the tunnel.

An apparatus comprising:

• a memory configured to store data;
• a network interface configured to enable communications over a communications network;
• a processor operable to execute instructions associated with the data, wherein the processor is operable to:
• obtain a packet of a traffic flow at an ingress node of the communications network;
• calculate a shortest path between a beginning of a current segment of a tunnel associated with a first segment-switched path and an end of the current segment;
• route the packet to an egress node of the communications network via either the first segment-switched path or a second segment-switched path different than the first segment-switched path depending on whether the packet was obtained from a first node external to the communications network or from a second node internal to the communications network;
• determine whether or not the shortest path traverses a head end of the tunnel;
• and
• use either the tunnel or a different tunnel to implement the first segment-switched path depending on whether the shortest path traverses the head end of the tunnel.