Method of enabling a packet loss measurement in a packet transport network

1. Method of enabling a packet loss measurement in a network, the method comprising:

receiving at a group of user ports data packets containing a same source address and a same destination address;

performing a link aggregation of said group of user ports, by,

at each user port of said group, adding to each data packet received at a respective user port an internal header element indicating said respective user port and a same network port, and,

at a switching device, switching said received data packets from said user ports to said same network port using the added internal header elements;

at said network port,

transmitting said data packets to a far end network edge node, and

determining a number of said transmitted data packets;

determining for each of said user ports a respective number of data packets lost internally during the transmission from the respective user port to said network port using said added internal header elements;

determining a corrected number of transmitted data packets using said determined numbers of data packets lost internally during the transmission from the respective user port to said network port, wherein said corrected number of transmitted data packets is the sum of the determined number of said transmitted data packets and an overall number data packets lost internally during the transmission from said user ports to said network port; and

indicating at said network port said corrected number of transmitted data packets to said far end network edge node.

2. Method according to claim 1 , furthermore comprising:

at said network port,

receiving second data packets containing a second source address equal to said first destination address and a second destination address equal to said first source address, and

determining a second number of said received second data packets;

performing a link aggregation of said user ports, by,

at said network port, adding to each of said received second data packets an internal header element indicating one of said user ports, and,

at said switching device, switching said received second data packets to one of said user ports using said added internal header elements;

determining for each of said user ports a respective number of second data packets lost internally during the transmission from said network port to the respective user port; and

determining a corrected number of received second data packets using said determined numbers of second data packets lost internally during the transmission from said network port to the respective user port.

3. Method according to claim 2 , furthermore comprising:

determining for each of said user ports said respective number of second data packets lost internally during the transmission from said network port to the respective user port at a respective periodicity; and

determining the overall number of second data packets lost internally during the transmission from said network port to said user ports at an overall periodicity, by summing said determined respective numbers of second data packets lost during the transmission from said network port to the respective user ports over an overall time interval reciprocal to said overall periodicity.

4. Method according to claim 3 ,

wherein said overall number of second data packets lost internally is determined for consecutive overall time intervals;

and wherein at least a fraction of an overall number of second data packets lost internally determined for a first time interval is taken into account for determining a corrected number of received second data packets of a second overall time interval, consecutive to said first overall time interval.

5. Method according to claim 2 , furthermore comprising:

at said network port, indicating said corrected number of received second data packets to said far end network edge node; and

at said far end network edge node,

determining a number of transmitted second data packets,

receiving the indication of said corrected number of received second data packets, and

determining a number of second data packets lost during the transmission from said far end network edge node to said user ports, by subtracting said indicated corrected number of received second data packets from said determined number of second data packets.

6. Method according to claim 2 , furthermore comprising:

at said network port,

receiving an indication of a number of second data packets transmitted by said far end network edge node, and

determining a number of second data packets lost during the transmission from said far end network edge node to said user ports, by subtracting said corrected number of received second data packets from said indicated number of second data packets.

7. Method according to claim 1 , furthermore comprising:

determining for each of said user ports said respective number of data packets lost internally during the transmission from the respective user port to said network port at a respective periodicity; and

determining the overall number of data packets lost internally during the transmission from said user ports to said network port at an overall periodicity, by summing said determined respective numbers of data packets lost internally during the transmission from the respective user ports to said network port an overall time interval reciprocal to said overall periodicity.

8. Method according to claim 1 , furthermore comprising:

at said network port,

receiving an indication of a number of data packets, containing said source address and said destination address, received by said far end network edge node, and

determining a number of data packets lost during the transmission from said user ports to said far end network edge node, by subtracting said indicated number of data packets received by said far end network edge node from said corrected number of transmitted data packets.

9. Method according to claim 1 , furthermore comprising:

at said far end network edge node,

receiving the indication of said corrected number of transmitted data packets,

determining a received number of data packets containing said source address and said destination address, and

determining a number of data packets lost during the transmission from said user ports to said far end network edge node, by subtracting said determined received number of packets from said corrected number of transmitted data packets.

10. Network edge node, comprising:

at least one first line card comprising a group of at least two user ports, and at least one packet processor connected to said user ports;

at least one second line card comprising at least one network port and a packet processor connected to said network port; and

a switching device connecting said at least first and said at least second line cards;

wherein said at least one first line card is adapted to receive via said at least two user ports data packets, and wherein said at least one second line card is adapted to transmit data packets via said network port to a far end network edge node;

wherein said at least one packet processor of said at least first line card is adapted to add to data packets, which are received via said at least two user ports and which contain a same source address and a same destination address, an internal header element indicating the respective user port at which the data packet was received and also said network port;

wherein said switching device is configurable to switch said received data packets from said at least two user ports to said network port, using said added internal header elements;

wherein said packet processor of said second line card is adapted to determine a number of data packets, which are transmitted to said far end network edge node and which contain said same source address and said same destination address;

wherein said packet processors are adapted to determine for each of said at least two user ports a respective number of data packets lost internally during the transmission from the respective user port to said network port, using said added internal header elements;

and wherein said packet processor of said at least one second line card is adapted to determine a corrected number of transmitted data packets using said determined numbers of data packets lost internally during the transmission from the respective user port to said network port, wherein said corrected number of transmitted data packets is the sum of the determined number of said transmitted data packets and an overall number of data packets lost internally during the transmission from said user ports to said network port, and

to indicate said corrected number of transmitted data packets to said far end network edge node.