U-turn indicator in internet protocol packets
A network includes a first node having a processor that incorporates a U-turn indicator into a header of an Internet protocol (IP) packet for transmission along a first path towards a second node. The U-turn indicator indicates that the first node expects to receive the IP packet back from the second node. The first node also includes a transceiver that transmits the IP packet including the header having the U-turn indicator along the first path. In some cases, the transceiver (or another transceiver in another node) receives a packet comprising a U-turn indicator. The processor (or another processor in another node) detects the U-turn indicator in a header of the IP packet. The processor forwards the IP packet along a path to a destination node that does not include the node that originally transmitted the IP packet or drops the IP packet depending on whether an alternate path is identified.
1. A method comprising:
receiving, at a node, an Internet Protocol (IP) packet intended for a destination node, wherein an IP header of the IP packet includes a destination address field that includes an address of the destination node;
determining, by the node based on a failure associated with a first path toward the destination node, to reroute the IP packet toward a backup next hop node associated with a second path toward the destination node;
modifying, by the node based on a determination that the second path is a U-turn path, the IP packet to form a modified IP packet by including a U-turn indicator in the IP header of the IP packet, including the address of the destination node in the U-turn indicator, and replacing the address of the destination node with an address of the backup next hop node in the destination address field; and
transmitting, from the node toward the backup next hop node via the second path, the modified IP packet.
2. The method of claim 1 , wherein the U-turn indicator comprises a source address of the node which inserted the U-turn indicator into the IP packet.
3. The method of claim 1 , wherein the U-turn indicator comprises at least one flag.
4. The method of claim 3 , wherein the at least one flag comprises at least one of a first flag encoding an indication that the IP packet is being fast rerouted along an alternate path from the node to the destination node, a second flag encoding an indication that the IP packet previously performed a U-turn, or a third flag encoding information indicating that a source address of the node which inserted the U-turn indicator into the IP packet is included in the U-turn indicator.
5. The method of claim 1 , wherein the determination that the second path is a U-turn path is based on an entry in a routing table at the node.
6. An apparatus, comprising:
at least one processor;
at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to at least:
receive, at a node, an Internet Protocol (IP) packet intended for a destination node, wherein an IP header of the IP packet includes a destination address field that includes an address of the destination node;
determine, by the node based on a failure associated with a first path toward the destination node, to reroute the IP packet toward a backup next hop node associated with a second path toward the destination node;
modify, by the node based on a determination that the second path is a U-turn path, the IP packet to form a modified IP packet by including a U-turn indicator in the IP header of the IP packet, including the address of the destination node in the U-turn indicator, and replacing the address of the destination node with an address of the backup next hop node in the destination address field; and
transmit, from the node toward the backup next hop node via the second path, the modified IP packet.
7. The apparatus of claim 6 , wherein the U-turn indicator comprises a source address of the node which inserted the U-turn indicator into the IP packet.
8. The apparatus of claim 6 , wherein the U-turn indicator comprises at least one flag.
9. The apparatus of claim 6 , wherein the at least one flag comprises at least one of a first flag encoding an indication that the IP packet is being fast rerouted along an alternate path from the node to the destination node, a second flag encoding an indication that the IP packet previously performed a U-turn, or a third flag encoding information indicating that a source address of the node which inserted the U-turn indicator into the IP packet is included in the U-turn indicator.
10. The apparatus of claim 6 , wherein the determination that the second path is a U-turn path is based on an entry in a routing table at the node.
11. An apparatus, comprising:
at least one processor;
at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to at least:
receive, at a node, an Internet Protocol (IP) packet intended for a destination node, wherein the IP packet includes an IP header, wherein the IP header includes a destination address field and a U-turn indicator, wherein the destination address field includes an address of the node, wherein the U-turn indicator includes an address of the destination node;
perform, at the node based on a determination that the destination address field includes the address of the node and based on a determination that the IP header includes the U-turn indicator, a lookup for a primary path for the IP packet based on the address of the destination node in the U-turn indicator;
identify, by the node based on a determination that the primary path for the IP packet is a U-turn path for the IP packet, a second path from the node toward the destination node; and
forward, by the node along the second path from the node toward the destination node, the IP packet.
12. The apparatus of claim 11 , wherein the second path is a loop-free alternate path.
13. The apparatus of claim 11 , wherein the second path is a back-up U-turn path.
14. The apparatus of claim 11 , wherein the U-turn indicator comprises a source address of a node which inserted the U-turn indicator into the IP packet.
15. The apparatus of claim 11 , wherein the U-turn indicator comprises at least one flag.
16. The apparatus of claim 15 , wherein the at least one flag comprises at least one of a first flag encoding an indication that the IP packet is being fast rerouted along an alternate path from the node to the destination node, a second flag encoding an indication that the IP packet previously performed a U-turn, or a third flag encoding information indicating that a source address of a node which inserted the U-turn indicator into the IP packet is included in the U-turn indicator.
17. A method comprising:
receiving, at a node, an Internet Protocol (IP) packet intended for a destination node, wherein the IP packet includes an IP header, wherein the IP header includes a destination address field and a U-turn indicator, wherein the destination address field includes an address of the node, wherein the U-turn indicator includes an address of the destination node;
performing, at the node based on a determination that the destination address field includes the address of the node and based on a determination that the IP header includes the U-turn indicator, a lookup for a primary path for the IP packet based on the address of the destination node in the U-turn indicator;
identifying, by the node based on a determination that the primary path for the IP packet is a U-turn path for the IP packet, a second path from the node toward the destination node; and
forwarding, by the node along the second path from the node toward the destination node, the IP packet.
18. The method of claim 17 , wherein the second path is a loop-free alternate path.
19. The method of claim 17 , wherein the second path is a back-up U-turn path.
20. The method of claim 17 , wherein the U-turn indicator comprises a source address of a node which inserted the U-turn indicator into the IP packet.
21. The method of claim 17 , wherein the U-turn indicator comprises at least one flag.
22. The method of claim 21 , wherein the at least one flag comprises at least one of a first flag encoding an indication that the IP packet is being fast rerouted along an alternate path from the node to the destination node, a second flag encoding an indication that the IP packet previously performed a U-turn, or a third flag encoding information indicating that a source address of a node which inserted the U-turn indicator into the IP packet is included in the U-turn indicator.