US 8,427,969 B1Granted

System and method for calculating passive host proximity in an L2 link layer

AssigneeApplied Micro Circuits Corporation

InventorLoic Juillard

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Abstract

A system and method are provided for calculating passive host proximity in an environment of network-connected hosts. At least three controller hosts send inquiries to target hosts in the environment, including at least two passive (non-controller) hosts. A time interval is recorded between each inquiry and an associated response, and the recorded time intervals are converted into logical distance measurements between the controller host and each target host. The logical distance measurements are then used to calculate a logical distance between the two passive hosts. A logical triangle is constructed between a first controller host (H1) and the two passive hosts (S1, S2) using a first logical distance side (H1S1) having a known value, a second logical distance side (H1S2) having a known value, and a third logical distance side (S1S2) having an unknown value. Trigonometric relationships solve for the unknown value of the third logical distance side.

Claims20

Dependent claims

In an environment including local area network (LAN) cable-connected hosts, a method for indirectly calculating logical distance between passive hosts, the method comprising:

in an environment of LAN cable-connected hosts, at least three controller hosts sending inquiries to target hosts in the environment including at least two passive (non-controller) hosts;
recording a time interval between each inquiry and an associated response;
converting the recorded time intervals into logical distance measurements between the controller host and each target host, where logical distance is a measurement of propagation delay's through LAN cabling and switching/routing speeds of intervening hosts;
and
using the logical distance measurements, calculating a logical distance between the two passive hosts;
wherein calculating the logical distance between the two passive hosts includes:
constructing a logical triangle between a first controller host (H1) and the two passive hosts (S1, S2) using a first logical distance side (H1S1) having a known value, a second logical distance side (H1S2) having a known value, and a third logical distance side (S1S2) having an unknown value;
and,
using trigonometric relationships, solving for the unknown value of the third logical distance side, wherein using trigonometric relationships to solve for the unknown value of the third logical distance side includes:
if S1 and S2 are on the same side of a logical distance side H1H2, finding α1=α3−α2;
where α1 is the angle formed by logical distance sides H1S1 and H1S2;
where α2 is the angle formed by logical distance sides H1H2 and H1S1, where H2 is a second controller host;
where α3 is the angle formed by logical distance sides H1H2 and H1S2;
if S1 and S2 are on opposite sides of the logical distance side H1H2, finding α1=α3+α2;
and,
knowing α1, H1S1, and H1S2, solving for S1S2.

13 more elements

In an environment including local area network (LAN) cable-connected hosts, a controller host indirectly calculating logical distance between passive hosts, the controller host comprising:

a network interface transceiver for sending inquiries to target hosts in an environment including at least three network-connected controller hosts and at least two network-connected passive (non-controller) hosts, and for receiving logical distances measurements made by other controller hosts in the environment;
and,
a proximity module, implemented by a processor, for recording a time interval between each inquiry and an associated response, converting the recorded time intervals into logical distance measurements between the controller host and target hosts, and calculating a logical distance between two passive hosts using the measured and received logical distances, where logical distance is a measurement of propagation delays through LAN cabling and switching/routing speeds of intervening hosts;
wherein the proximity module calculates the logical distance between the two passive hosts as follows:
constructing a logical triangle between a first controller host (H1) and the two passive hosts (S1, S2) using a first logical distance side (H1S1) having a known value, a second logical distance side (H1S2) having a known value, and a third logical distance side (S1S2) having an unknown value;
and,
using trigonometric relationships, solving for the unknown value of the third logical distance side;
and,
wherein the proximity module uses trigonometric relationships to solve for the unknown value of the third logical distance side follows:
if S1 and S2 are on the same side of a logical distance side H1H2, finding α1=α3−α2;
where α1 is the angle formed by logical distance sides H1S1 and H1S2;
where α2 is the angle formed by logical distance sides H1H2 and H1S1, where H2 is a second controller host;
where α3 is the angle formed by logical distance sides H1H2 and H1S2;
if S1 and S2 are on opposite sides of the logical distance side H1H2, finding α1=α3+α2;
and,
knowing α1, H1S1, and H1S2, solving for S1S2.

13 more elements

Dependencies are inferred from the claim text.