Probing a network
A method is presented of probing a network using probing with a probe packet pair, the pair comprising a first probe packet (L 1 ) and a second probe packet (L 2 ), and wherein L 1 >L 2 . The L 1 probe packet is transmitted before L 2 and the probe packets are arranged to be back-to-back on the last link. Use of the method provides the capacity of the last link in the probed path. The method may be run from a gateway in a network to probe aspects of the network and is suitable for probing a domestic network behind a home gateway. A use for the method is also described.
1. A method of probing a network using a probe packet pair, the network comprising a network path, and the probe packet pair comprising a first probe packet designated L 1 and a second probe packet designated L 2 , wherein the size of L 1 is greater than the size of L 2 ,
the method comprising:
transmitting L 1 and L 2 of the probe packet pair over the network path, wherein L 1 of the probe packet pair is transmitted before L 2 of the probe packet pair, wherein the network path comprises two or more network links; and
arranging L 1 and L 2 to be back-to-back on the last of the two or more links of the network path by transmitting one or more further probe packet pairs, each comprising a first probe packet designated L 1 and a second probe packet designated L 2 , wherein for each of the one or more further probe packet pairs, the size of L 1 is greater than the size of L 2 , and varying, for each successive transmission of a further probe packet pair, a ratio between the two packet sizes in the further probe pair with respect to the ratio of the sizes of L 1 and L 2 in the probe packet pair until two probe packet pairs from among those transmitted produce the same observed capacity.
2. The method of claim 1 , wherein varying a ratio between two packet sizes comprises gradually reducing the size of L 2 in the successive transmissions of the further probe packet pairs.
3. The method of claim 1 , wherein further probe pairs are transmitted until an observed capacity is the same for consecutive measurements.
4. The method of claim 1 , wherein the size of L 1 being greater than the size of L 2 corresponds to the length of L 1 being greater than the length of L 2 .
5. The method according to claim 1 , where L 1 is the same size as a smallest Maximum Transfer Unit found in the network path.
6. The method according to claim 1 , wherein the network comprises a gateway device and the probing is performed from the gateway device.
7. The method of claim 6 wherein the probing is controlled remotely from outside the network.
8. The method according claim 1 , wherein the network is a home network.
9. A gateway for a network, wherein the gateway is configured to probe a network path in the network using a probe packet pair, the probe pair comprising a first probe packet designated L 1 and a second probe packet designated L 2 , wherein the size of L 1 is greater than the size of L 2 , and wherein the gateway comprises:
a processor and instructions that when executed by the processor cause the gateway to carry out operations including:
transmitting L 1 of the probe packet pair over the network path, wherein the network path comprises two or more network links; and
after transmitting L 1 of the probe packet pair, transmitting L 2 of the probe packet pair over the network path,
wherein the transmissions of L 1 and L 2 are arranged to be back-to-back on the last link of the network path by transmitting one or more further probe packet pairs, each comprising a first probe packet designated L 1 and a second probe packet designated L 2 , wherein for each of the one or more further probe packet pairs, the size of L 1 is greater than the size of L 2 , and varying, for each successive transmission of a further probe packet pair, a ratio between the two packet sizes in the further probe pair with respect to the ratio of the sizes of L 1 and L 2 in the probe packet pair until two probe packet pairs from among those transmitted produce the same observed capacity.
10. A test apparatus for probing a remote network, the test apparatus having access to a network by way of a gateway in the network, and the test apparatus being configured to probe a network path in the network via the gateway using a probe packet pair, the probe pair comprising a first probe packet designated L 1 and a second probe packet designated L 2 , wherein the size of L 1 is greater than the size of L 2 , and wherein the test apparatus comprises:
a processor and instructions that when executed by the processor cause the test apparatus to carry out operations including:
transmitting L 1 of the probe packet pair over the network path, wherein the network path comprises two or more network links; and
after transmitting L 1 of the probe packet pair, transmitting L 2 of the probe packet pair over the network path,
wherein the transmissions of L 1 and L 2 are arranged to be back-to-back on the last link of the network path by transmitting one or more further probe packet pairs, each comprising a first probe packet designated L 1 and a second probe packet designated L 2 , wherein for each of the one or more further probe packet pairs, the size of L 1 is greater than the size of L 2 , and varying, for each successive transmission of a further probe packet pair, a ratio between the two packet sizes in the further probe pair with respect to the ratio of the sizes of L 1 and L 2 in the probe packet pair until two probe packet pairs from among those transmitted produce the same observed capacity.
11. A test apparatus configured to probe a network path in a network using a probe packet pair, wherein the probe pair comprises a first probe packet designated L 1 and a second probe packet designated L 2 , and wherein the size of L 1 is greater than the size of L 2 , and wherein the test apparatus comprises:
a processor and instructions that when executed by the processor cause the test apparatus to carry out operations including:
transmitting L 1 of the probe packet pair over the network path, wherein the network path comprises two or more network links; and
after transmitting L 1 of the probe packet pair, transmitting L 2 of the probe packet pair over the network path,
wherein the transmissions of L 1 and L 2 are arranged to be back-to-back on the last link of the network path by transmitting one or more further probe packet pairs, each comprising a first probe packet designated L 1 and a second probe packet designated L 2 , wherein for each of the one or more further probe packet pairs, the size of L 1 is greater than the size of L 2 , and varying, for each successive transmission of a further probe packet pair, a ratio between the two packet sizes in the further probe pair with respect to the ratio of the sizes of L 1 and L 2 in the probe packet pair until two probe packet pairs from among those transmitted produce the same observed capacity.