Hitless switchover and bandwidth sharing in a communication network
View Patent ↗Described is a node comprising a switch fabric and first and second ingress modules. The first ingress module receives a first stream of packets from a first physical path through the network; forwards a copy of the first stream of packets to an intermodule communication channel; selects packets from the first stream of packets and a copy of a second stream of packets for forwarding to the switch fabric. The second ingress module receives the second stream of packets from a second physical path through the network; forwards the copy of the second stream of packets to the intermodule communication channel; and selects packets from the copy of the first stream of packets and the second stream of packets for forwarding to the switch fabric based on sequence numbers in the packets.
1. A node for a packet communication network, the node comprising:
a switch fabric; and
first and second ingress modules, the first ingress module being configured:
to receive a first stream of packets from a first physical path through the network;
to forward a copy of the first stream of packets to an intermodule communication channel;
to receive a copy of a second stream of packets from the second ingress module; and
when selected to forward packets to the switch fabric, to select packets from the first stream of packets and the copy of the second stream of packets for forwarding as a single packet stream to the switch fabric based on sequence numbers in the packets;
the second ingress module being configured:
to receive the second stream of packets from a second physical path through the network;
to forward the copy of the second stream of packets to the intermodule communication channel;
to receive the copy of the first stream of packets from the intermodule communication channel; and
when selected to forward packets to the switch fabric, to select packets from the copy of the first stream of packets and the second stream of packets for forwarding as a single packet stream to the switch fabric based on sequence numbers in the packets;
the first and second ingress modules being configured such that, at any time, only one of the first and second ingress modules is selected to forward packets to the switch fabric.
2. The node of claim 1 , wherein the selected one of the first and second ingress modules is selected based on a protection control signal.
3. The node of claim 1 , wherein at least some of the packets in the first stream of packets have sequence numbers that are the same as at least some of the sequence numbers in the second stream of packets.
4. The node of claim 1 , wherein the first ingress module is configured, on failure of the first physical path through the network when the first ingress module is selected, to select packets for forwarding to the switch fabric, and to select packets from the copy of the second stream of packets for forwarding to the switch fabric.
5. The node of claim 4 , wherein the second ingress module is configured, on failure of the second physical path through the network when the second ingress module is selected, to select packets for forwarding to the switch fabric, and to select packets from the copy of the first stream of packets for forwarding to the switch fabric.
6. The node of claim 1 , wherein:
the first ingress module is configured, on failure of the second ingress module, to select packets from the first stream of packets for forwarding to the switch fabric; and
the second ingress module is configured, on failure of the first ingress module, to select packets from the second stream of packets for forwarding to the switch fabric.
7. The node of claim 1 , wherein the first and second ingress modules are configured, when selected to forward packets to the switch fabric, to select packets from the first and second stream of packets for forwarding to the switch fabric based on sequence numbers by comparing the sequence numbers to expected sequence numbers.
8. The node of claim 7 , wherein the packets in the single packet stream are in an order based on the sequence numbers of those packets.
9. The node of claim 1 , wherein:
the node comprises a label switched router;
the first packet stream comprises a packet stream of a label switched path; and
the second packet stream comprises a packet stream of a label switched path.
10. The node of claim 9 , wherein:
the first packet stream comprises a packet stream of a first label switched path;
the second packet stream comprises a packet stream of a second label switched path; and
the single stream of packets forwarded by the selected ingress module to the switch fabric comprises a packet stream of a third label switched path.
11. A method of operating a node for a packet communication network, the method comprising:
operating a first ingress module:
to receive a first stream of packets from a first physical path through the network;
to forward a copy of the first stream of packets to an intermodule communication channel;
to receive a copy of a second stream of packets from a second ingress module; and
when selected to forward packets to the switch fabric, to select packets from the first stream of packets and the copy of the second stream of packets for forwarding as a single packet stream to the switch fabric based on sequence numbers in the packets;
operating the second ingress module:
to receive the second stream of packets from a second physical path through the network;
to forward the copy of the second stream of packets to the intermodule communication channel;
to receive the copy of the first stream of packets from the intermodule communication channel; and
when selected to forward packets to the switch fabric, to select packets from the copy of the first stream of packets and the second stream of packets for forwarding as a single packet stream to the switch fabric based on sequence numbers in the packets; and
operating the first and second ingress modules such that, at any time, only one of the first and second ingress modules is selected to forward packets to the switch fabric.
12. The method of claim 11 , wherein the selected one of the first and second ingress modules is selected based on a protection control signal.
13. The method of claim 11 , wherein at least some of the packets in the first stream of packets have sequence numbers that are the same as at least some of the sequence numbers in the second stream of packets.
14. The method of claim 11 , comprising operating the first ingress module, on failure of the first physical path through the network when the first ingress module is selected, to select packets for forwarding to the switch fabric, and to select packets from the copy of the second stream of packets for forwarding to the switch fabric.
15. The method of claim 14 , comprising operating the second ingress module, on failure of the second physical path through the network when the second ingress module is selected, to select packets for forwarding to the switch fabric, and to select packets from the copy of the first stream of packets for forwarding to the switch fabric.
16. The method of claim 11 , comprising:
on failure of the second ingress module, operating the first ingress module to select packets from the first stream of packets for forwarding to the switch fabric; and
on failure of the first ingress module, operating the second ingress module to select packets from the second stream of packets for forwarding to the switch fabric.
17. The method of claim 11 , comprising operating each ingress module, when selected to forward packets to the switch fabric, to select packets from the first and second streams of packets for forwarding towards the switch fabric based on sequence numbers by comparing the sequence numbers to expected sequence numbers.
18. The method of claim 17 , wherein the packets in the single packet stream are in an order based on the sequence numbers of those packets.
19. The method of claim 11 , wherein:
the node comprises a label switched router;
the first packet stream comprises a packet stream of a label switched path; and
the second packet stream comprises a packet stream of a label switched path.
20. The method of claim 19 , wherein:
the first packet stream comprises a packet stream of a first label switched path;
the second packet stream comprises a packet stream of a second label switched path; and
the single stream of packets forwarded by the selected ingress module to the switch fabric comprises a packet stream of a third label switched path.