Link status monitoring based on packet loss detection
In exemplary embodiments of the present invention, special metadata is added to link monitoring protocol messages exchanged by pairs of adjacent nodes to allow such nodes to detect communication link failures and determine whether the failure affects an incoming communication link or an outgoing communication link. The link monitoring protocol messages may be augmented BFD messages.
1. A system comprising:
a source node comprising a first plurality of communication interfaces, a first memory storing first routing information, and a first packet router; and
a target node comprising a second plurality of communication interfaces, a second memory storing second routing information, and a second packet router,
wherein the source node is configured to transmit a series of distinct forward link monitoring protocol messages destined for the target node over a first communication interface of the source node according to the stored first routing information, each distinct forward link monitoring protocol message having a metadata portion including a distinct forward sequence number; receive a series of return link monitoring protocol messages from the target node over a second communication interface of the source node, each return link monitoring protocol message responsive to a distinct forward link monitoring protocol message and having a metadata portion including a forward sequence number from the received forward link monitoring protocol message and a distinct return sequence number; determine if a communication problem occurred based on the forward and reverse sequence numbers in the series of received return link monitoring protocol messages; and when the source node determines that a communication problem occurred, determine whether the communication problem is associated with an outgoing communication link to the target node or an incoming communication link from the target node based on the forward and reverse sequence numbers in the series of received return link monitoring protocol messages; and
wherein the target node is configured to receive a forward link monitoring protocol message including a distinct forward sequence number over a first communication interface of the target node, format a return link monitoring protocol message including the distinct forward sequence number and a distinct return sequence number, and transmit the return link monitoring protocol message destined for the source node over a second communication interface of the target node according to the stored second routing information.
2. A system according to claim 1 , wherein the forward and return link monitoring protocol messages are augmented Bidirectional Forwarding Detection (BFD) messages.
3. A system according to claim 1 , wherein the source node increments the forward sequence number for each forward link monitoring protocol message it transmits, and wherein the target node increments the return sequence number for each return link monitoring protocol message it transmits.
4. A method of link status monitoring by a source node in a communication system, the source node in communication with a target node, the method comprising:
transmitting, by a source node destined for the target node, a series of distinct forward link monitoring protocol messages, each distinct forward link monitoring protocol message having a metadata portion including a distinct forward sequence number;
receiving, by the source node from the target node, a series of return link monitoring protocol messages, each return link monitoring protocol message responsive to a distinct forward link monitoring protocol message and having a metadata portion including a forward sequence number from the received forward link monitoring protocol message and a distinct return sequence number;
determining, by the source node, if a communication problem occurred based on the forward and reverse sequence numbers in the series of received return link monitoring protocol messages; and
when the source node determines that a communication problem occurred, determining, by the source node, whether the communication problem is associated with an outgoing communication link to the target node or an incoming communication link from the target node based on the forward and reverse sequence numbers in the series of received return link monitoring protocol messages.
5. A method according to claim 4 , wherein the forward and return link monitoring protocol messages are augmented Bidirectional Forwarding Detection (BFD) messages.
6. A method according to claim 4 , wherein the source node increments the forward sequence number for each forward link monitoring protocol message it transmits.
7. A source node for use with a target node, the source node comprising:
a memory for storing routing information;
a plurality of communication interfaces; and
a packet router configured to implement a link status monitoring method comprising:
transmitting, by the packet router over a first communication interface according to the stored routing information, a series of distinct forward link monitoring protocol messages destined for the target node, each distinct forward link monitoring protocol message having a metadata portion including a distinct forward sequence number;
receiving, by the packet router from the target node over a second communication interface, a series of return link monitoring protocol messages, each return link monitoring protocol message responsive to a distinct forward link monitoring protocol message and having a metadata portion including a forward sequence number from the received forward link monitoring protocol message and a distinct return sequence number;
determining, by the packet router, if a communication problem occurred based on the forward and reverse sequence numbers in the series of received return link monitoring protocol messages; and
when the packet router determines that a communication problem occurred, determining, by the packet router, whether the communication problem is associated with an outgoing communication link to the target node or an incoming communication link from the target node based on the forward and reverse sequence numbers in the series of received return link monitoring protocol messages.
8. A source node according to claim 7 , wherein the forward and return link monitoring protocol messages are augmented Bidirectional Forwarding Detection (BFD) messages.
9. A source node according to claim 7 , wherein the packet router increments the forward sequence number for each forward link monitoring protocol message it transmits.
10. A computer program product comprising a tangible, non-transitory computer readable medium having embodied therein a computer program that, when run on at least one computer processor, implements a packet router for a source node, the packet router implementing a link status monitoring method comprising:
transmitting, by the packet router, a series of distinct forward link monitoring protocol messages, each distinct forward link monitoring protocol message having a metadata portion including a distinct forward sequence number;
receiving, by the packet router, a series of return link monitoring protocol messages, each return link monitoring protocol message responsive to a distinct forward link monitoring protocol message and having a metadata portion including a forward sequence number from the received forward link monitoring protocol message and a distinct return sequence number;
determining, by the packet router, if a communication problem occurred based on the forward and reverse sequence numbers in the series of received return link monitoring protocol messages; and
when the packet router determines that a communication problem occurred, determining, by the packet router, whether the communication problem is associated with an outgoing communication link to the target node or an incoming communication link from the target node based on the forward and reverse sequence numbers in the series of received return link monitoring protocol messages.
11. A computer program product according to claim 10 , wherein the forward and return link monitoring protocol messages are augmented Bidirectional Forwarding Detection (BFD) messages.
12. A computer program product according to claim 10 , wherein the packet router increments the forward sequence number for each forward link monitoring protocol message it transmits.
13. A method of link status monitoring by a target node in a communication system, the method comprising:
receiving, by the target node from a source node, a forward link monitoring protocol message having a metadata portion including a distinct forward sequence number;
formatting, by the target node, a return link monitoring protocol message having a metadata portion including the distinct forward sequence number and a distinct return sequence number; and
transmitting the return link monitoring protocol message by the target node to the source node.
14. A method according to claim 13 , wherein the forward and return link monitoring protocol messages are augmented Bidirectional Forwarding Detection (BFD) messages.
15. A method according to claim 13 , wherein the target node increments the return sequence number for each return link monitoring protocol message it transmits.
16. A target node for use with a source node configured to transmit a series of distinct forward link monitoring protocol messages to the target node, each distinct forward link monitoring protocol message having a metadata portion including a distinct forward sequence number, the target node comprising:
a memory for storing routing information;
a plurality of communication interfaces; and
a packet router configured to implement a link status monitoring method comprising:
receiving, by the packet router from the source node over a first communication interface, at least one of the forward link monitoring protocol messages from the source node, each received forward link monitoring protocol message having a metadata portion including a distinct forward sequence number; and
for each received forward link monitoring protocol message:
(a) formatting, by the packet router, a return link monitoring protocol message having a metadata portion including the distinct forward sequence number from the received forward link monitoring protocol message and a distinct return sequence number; and
(b) transmitting the return link monitoring protocol message by the packet router destined for the source node over a second communication interface according to the stored routing information, wherein the return link monitoring protocol messages enable the source node to determine if a communication problem occurred based on the forward and reverse sequence numbers in return link monitoring protocol messages received from the target node, and when the source node determines that a communication problem occurred, further enable the source node to determine whether the communication problem is associated with an outgoing communication link to the target node or an incoming communication link from the target node based on the forward and reverse sequence numbers in the received return link monitoring protocol messages.
17. A target node according to claim 16 , wherein the forward and return link monitoring protocol messages are augmented Bidirectional Forwarding Detection (BFD) messages.
18. A target node according to claim 16 , wherein the packet router increments the return sequence number for each return link monitoring protocol message it transmits.
19. A computer program product comprising a tangible, non-transitory computer readable medium having embodied therein a computer program that, when run on at least one computer processor, implements a packet router for a target node that is used with a source node configured to transmit a series of distinct forward link monitoring protocol messages to the target node, each distinct forward link monitoring protocol message having a metadata portion including a distinct forward sequence number, the packet router implementing a link status monitoring method comprising:
receiving, by the packet router from the source node, at least one of the forward link monitoring protocol messages from the source node, each received forward link monitoring protocol message having a metadata portion including a distinct forward sequence number; and
for each received forward link monitoring protocol message:
(a) formatting, by the packet router, a return link monitoring protocol message having a metadata portion including the distinct forward sequence number from the received forward link monitoring protocol message and a distinct return sequence number; and
(b) transmitting the return link monitoring protocol message by the packet router destined for the source node, wherein the return link monitoring protocol messages enable the source node to determine if a communication problem occurred based on the forward and reverse sequence numbers in return link monitoring protocol messages received from the target node, and when the source node determines that a communication problem occurred, further enable the source node to determine whether the communication problem is associated with an outgoing communication link to the target node or an incoming communication link from the target node based on the forward and reverse sequence numbers in the received return link monitoring protocol messages.
20. A computer program product according to claim 19 , wherein the forward and return link monitoring protocol messages are augmented Bidirectional Forwarding Detection (BFD) messages.
21. A computer program product according to claim 19 , wherein the packet router increments the return sequence number for each return link monitoring protocol message it transmits.