Performance monitoring of frame transmission in data network OAM protocols
Performance measurements for a network, such as delay, delay variation, and loss, are performed over layer-2. A PM frame is sent from a source MEP (Maintenance End Point) to a destination MEP. The PM frame is timestamped immediately prior to transmission, and the local clock at the destination MEP is noted immediately upon arrival. MIPs (Maintenance Intermediate Points) may also time stamp the PM frame. Preferably, each PM frame has an interval (session) identifier and a sequence number within the interval. The PM frames are received by and sent by PM modules within the nodes of the network. The PM modules include a Sender function for sending an interval of one or more PM frames and a Receiver function for receiving PM frames and computing measurements.
1. A method for performance monitoring in a network, comprising the steps of:
generating a plurality of layer-2 performance monitoring frames by a first node, wherein the performance monitoring frames include:
one or more type fields identifying the frame as a performance monitoring frame;
an interval session identifier identifying a specific performance measuring, interval of related performance monitoring frames;
a sequence number uniquely identifying each performance monitoring frame in the specific performance measuring interval;
an origination timestamp field specifying the time that the frame is transmitted; and
a padding field, wherein at least one of size and content of the padding field of one or more of the plurality of performance monitoring frames is varied during the specific performance measuring interval;
transmitting the plurality of performance monitoring frames through the network;
receiving the plurality of performance monitoring frames by a second node in the network and storing an arrival timestamp associated with the reception of the performance monitoring frames, wherein the second node determines that the specific performance measuring interval is being initiated in response to the interval session identifier of one of the received plurality of performance monitoring frames is different than interval session identifiers of previous performance monitoring frames; and
determining performance criteria from the origination and arrival timestamps of the performance monitoring frames.
2. The method of claim 1 , wherein a transmission interval of the plurality of the performance monitoring frames is varied during the specific performance measuring interval by transmitting the performance monitoring frames at varied time spacings.
3. The method of claim 1 , wherein content of the padding field is varied by varying a sequence of data bits in the padding field.
4. The method of claim 1 , wherein the size of the padding field of the performance monitoring frames is varied.
5. The method of claim 1 , wherein contents of the performance monitoring frames is varied.
6. The method of claim 1 , wherein the origination timestamp is generated immediately prior to transmitting the performance monitoring frames through the network.
7. The method of claim 1 wherein each performance monitoring frame further includes a type field for identifying the performance monitoring frame as an Ethernet Operations, Administration and Management (OAM) type performance monitoring frame, wherein the type field includes a management level identifier for customer, provider and operator networks.
8. The method of claim 1 wherein one or more nodes intermediate to the first and second nodes also generate a timestamp stored in the performance monitoring frame.
9. Circuitry for performance monitoring in a network, comprising:
circuitry for generating layer-2 performance monitoring frames by a first node, wherein the performance monitoring frames include one or more type fields identifying the frame as a performance monitoring frame, an interval session identifier identifying a specific performance measuring interval of related performance monitoring frames, a sequence number uniquely identifying each performance monitoring frame in the specific performance measuring interval, and an origination timestamp field specifying a time that the frame is transmitted and a padding field, wherein at least one of size and content of the padding field of one or more of the performance monitoring frames is varied during the specific performance measuring interval;
circuitry for transmitting the performance monitoring frames through the network during the specific performance measuring interval;
circuitry for receiving the performance monitoring frames by a second node in the network and storing an arrival timestamp associated with the reception of the performance monitoring frames, wherein the second node determines that the specific performance measuring interval is being initiated in response to the interval session identifier of one of the received performance monitoring frames is different than interval session identifiers of previous performance monitoring frames; and
circuitry for determining performance criteria from the origination and arrival timestamps of the performance monitoring frames.
10. The performance monitoring circuitry of claim 9 wherein the generating circuitry generates the performance monitoring frames at varied time spacings.
11. The performance monitoring circuitry of claim 9 wherein the generating circuitry generates performance monitoring frames wherein the content of the padding field is varied by varying a sequence of data bits in the padding field.
12. The performance monitoring circuitry of claim 11 wherein the generating circuitry generates performance monitoring frames wherein the size of the padding field is varied.
13. The performance monitoring circuitry of claim 9 wherein the generating circuitry stores the origination timestamp in the performance monitoring frame immediately prior to the transmitting of the performance monitoring frame.
14. The performance monitoring circuitry of claim 9 wherein the generating circuitry generates a type field for identifying the performance monitoring frame as an Ethernet Operations, Administration and Management (OAM) type performance monitoring frame, wherein the type field includes a management level identifier for customer, provider and operator.
15. The performance monitoring circuitry of claim 9 and further including one or more nodes intermediate to the first and second nodes that also generate a timestamp stored in the performance monitoring frame.
16. Circuitry for performance monitoring in a network node, comprising:
circuitry for receiving performance monitoring frames by the network node, wherein the performance monitoring frames have one or more type fields identifying the frame as a performance monitoring frame, an interval session identifier identifying a specific performance measurement interval of related performance monitoring frames, a sequence number uniquely identifying each performance monitoring frame in the specific performance measurement interval, an origination timestamp field specifying the time that the frame is transmitted and a padding field, wherein at least one of size and content of the padding field of one or more of the performance monitoring frames is varied during the specific performance measurement interval;
circuitry for determining that the performance measurement interval is being initiated in response to the interval session identifier of one of the received performance monitoring frames having a first value that is different than previous interval session identifiers; and
circuitry for determining performance criteria for the performance measurement interval from the origination and arrival timestamps of the performance monitoring frames with the interval session identifier having the first value.