Estimating network-layer topology using end-to-end measurements
A method for estimating the network-layer topology of a telecommunications network is described. In particular, the illustrative embodiment of the present invention estimates the existence and connectivity of nodes in the topology based on the detection of network-wide end-to-end path intersections. This is based on the assumption that pairs of streams of packets that share a common node will interfere and that the interference can be detected in the received streams. In general, this interference is manifested as jitter. By transmitting streams on each pair of end-to-end paths in the network, and detecting interference (or a lack of interference) a matrix of path intersections for the network can be created. Using logic and supposition, the topology of the network can be estimated using the matrix of path intersections. Once the estimate of the topology is complete, the maintenance and operation of the network can proceed based on the topology.
1. A method comprising:
transmitting a first stream of packets in a packet network, wherein:
i. the first stream of packets is transmitted from a first node n 1 to a second node n 2 via a first path p 1,2 in the packet network,
ii. the first stream comprises a first packet and a second packet, and
iii. the transmission of the first stream comprises a first temporal interval between the transmissions of the first packet and the second packet;
detecting interference by a first stream of packets on a second stream of packets in a packet network, wherein:
i. the second stream of packets is transmitted from a third node n 3 to a fourth node n 4 via a second path p 3,4 in the packet network,
ii. the second stream is transmitted concurrently with the first stream;
iii. the second stream comprises a third packet and a fourth packet, and
iv. the interference is detected when the first temporal interval corresponds to the temporal interval between the receptions of the third packet and the fourth packet at the fourth node n 4 ;
detecting interference by the first stream of packets on a third stream of packets in the packet network wherein:
i. the third stream of packets is transmitted from the third node n 3 to a fifth node n 5 via a third path p 3,5 in the packet network, and
ii. the third stream is transmitted concurrently with the first stream and the second stream;
iii. the third stream comprises a fifth packet and a sixth packet, and
iv. the interference is detected when the first temporal interval corresponds to the temporal interval between the receptions of the fifth packet and the sixth packet at the fifth node n 5 ;
deducing that both the second path p 3,4 and the third path p 3,5 comprise a sixth node n 6 because both the second stream of packets and the third stream of packets are interfered by the first stream of packets; and
transmitting a packet to transit the sixth node n 6 .
2. The method of claim 1 further comprising:
detecting no interference by the first stream of packets on a fourth stream of packets in the packet network wherein the fourth stream of packets is transmitted from the third node n 3 to a seventh node n 7 via a fourth path p 3,7 in the packet network;
deducing that the fourth path p 3,7 comprises an eighth node n 8 that is not in the second path p 3,4 or the third path p 3,5 because the fourth stream of packets is not interfered by the first stream of packets; and
transmitting a second packet to transit the eighth node n 8 .
3. A method comprising:
transmitting a first stream of packets in a packet network, wherein:
i. the first stream of packets is transmitted from a first node n 1 to a second node n 2 via a first path p 1,2 in the packet network,
ii. the first stream comprises a first packet and a second packet, and
iii. the transmission of the first stream comprises a first temporal interval between the transmissions of the first packet and the second packet;
detecting interference by a first stream of packets on a second stream of packets in a packet network, wherein:
i. the second stream of packets is transmitted from a third node n 3 to a fourth node n 4 via a second path p 3,4 in the packet network,
ii. the second stream is transmitted concurrently with the first stream;
iii. the second stream comprises a third packet and a fourth packet, and
iv. the interference is detected when the first temporal interval corresponds to the temporal interval between the receptions of the third packet and the fourth packet at the fourth node n 4 ;
detecting interference by the first stream of packets on a third stream of packets in the packet network, wherein:
i. the third stream of packets is transmitted from a fifth node n 5 to the fourth node n 4 via a third path p 5,4 in the packet network,
ii. the third stream is transmitted concurrently with the first stream and the second stream;
iii. the third stream comprises a fifth packet and a sixth packet,
iv. the interference is detected when the first temporal interval corresponds to a temporal interval between the receptions of the fifth packet and the sixth packet at the fourth node n 4 ;
deducing that both the second path p 3,4 and the third path p 5,4 comprise a sixth node n 6 because both the second stream of packets and the third stream of packets are interfered by the first stream of packets; and
transmitting a first packet to transit the sixth node n 6 .
4. The method of claim 3 further comprising:
detecting no interference by the first stream of packets on a fourth stream of packets in the packet network, wherein the fourth stream of packets is transmitted from a seventh node n 7 to the fourth node n 4 via a fourth path p 7,4 in the packet network;
deducing that the fourth path p 7,4 comprises a eighth node n 8 that is not in the second path p 3,4 or the third path p 5,4 because the fourth stream of packets is not interfered by the first stream of packets; and
transmitting a second packet to transit the eighth node n 8 .
5. A method comprising:
transmitting a first stream of packets in a packet network, wherein:
i. the first stream of packets is transmitted from a first node n 1 to a second node n 2 via a first path p 1,2 in the packet network,
ii. the first stream comprises a first packet and a second packet, and
iii. the transmission of the first stream comprises a first temporal interval between the transmissions of the first packet and the second packet;
detecting interference by a first stream of packets on a second stream of packets in a packet network, wherein:
i. the second stream of packets is transmitted from a third node n 3 to a fourth node n 4 via a second path p 3,4 in the packet network,
ii. the second stream is transmitted concurrently with the first stream;
iii. the second stream comprises a third packet and a fourth packet, and
iv. the interference is detected when the first temporal interval corresponds to the temporal interval between the receptions of the third packet and the fourth packet at the fourth node n 4 ;
detecting no interference by the first stream of packets on a third stream of packets in the packet network, wherein:
i. the third stream of packets is transmitted from the third node n 3 to a fifth node n 5 via a third path p 3,5 in the packet network;
ii. the third stream is transmitted concurrently with the first stream and the second stream;
iii. the third stream comprises a fifth packet and a sixth packet, and
iv. the interference is detected when the first temporal interval corresponds to the temporal interval between the receptions of the fifth packet and the sixth packet at the fifth node n 5 ;
deducing that the second path p 3,4 comprises a sixth node n 6 and that the third path p 3,5 does not comprise the sixth node n 6 because the second stream of packets is interfered by the first stream of packets but the third stream of packets is not interfered by the first stream of packets; and
transmitting a first packet to transit the sixth node n 6 .
6. A method comprising:
transmitting a first stream of packets in a packet network, wherein:
i. the first stream of packets is transmitted from a first node n 1 to a second node n 2 via a first path p 1,2 in the packet network,
ii. the first stream comprises a first packet and a second packet, and
iii. the transmission of the first stream comprises a first temporal interval between the transmissions of the first packet and the second packet;
detecting interference by a first stream of packets on a second stream of packets in a packet network, wherein:
i. the second stream of packets is transmitted from a third node n 3 to a fourth node n 4 via a second path p 3,4 in the packet network,
ii. the second stream is transmitted concurrently with the first stream;
iii. the second stream comprises a third packet and a fourth packet, and
iv. the interference is detected when the first temporal interval corresponds to the temporal interval between the receptions of the third packet and the fourth packet at the fourth node n 4 ;
detecting no interference by the first stream of packets on a third stream of packets in the packet network, wherein:
i. the third stream of packets is transmitted from a fifth node n 5 to the fourth node n 4 via a third path p 5,4 in the packet network,
ii. the third stream is transmitted concurrently with the first stream and the second stream;
iii. the third stream comprises a fifth packet and a sixth packet,
iv. the interference is detected when the first temporal interval corresponds to the temporal interval between the receptions of the fifth packet and the sixth packet at the fourth node n 4 ;
deducing that the second path p 3,4 comprises a sixth node n 6 and that the third path p 5,4 does not comprise sixth node n 6 because the second stream of packets is interfered by the first stream of packets but the third stream of packets is not interfered by the first stream of packets; and
transmitting a first packet to transit the sixth node n 6 .