US 6,195,330 B1Granted

Method and system for hit-less switching

OwnerDavid C. Sawey, Edmund K. Cherinventors

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Abstract

A system and method are disclosed for processing digital signals in a telecommunications system that allow hit-less switching between a first digital signal in which a first payload, a first payload indicator marker and a first overhead are transported on a first channel, and a second digital signal in which a second payload identical to the first payload, a second payload indicator marker and a second overhead are transported on a second channel. The present invention includes first and second pointer followers, first and second elastic buffers with control circuits, a monitor circuit, a multiplexer, and a pointer generator. The first and second elastic buffer control circuits each further comprise a write counter, a read counter, a phase detector, and a leak-out mechanism for reinitializing the system after a protection switch. The present invention hit-lessly selects between the first and second digital signals without having to frame align the signals.

Claims33

Dependent claims

A system for processing digital signals in a telecommunications system that allows hit-less switching between a first digital signal, in which a first payload, a first payload indicator marker and a first overhead are transported on a first channel, and a second digital signal, in which a second payload identical to the first payload, a second payload indicator marker and a second overhead are transported on a second channel, comprising:

a first pointer follower to receive the first signal, remove the first overhead, and forward the first payload and the first payload indicator marker;
a second pointer follower to receive the second signal, remove the second overhead, and forward the second payload and the second payload indicator marker;
a first elastic buffer with control circuit to receive the first payload and the first payload indicator marker, to forward the first payload indicator marker, and to forward the first payload;
a second elastic buffer with control circuit to receive the second payload and the second payload indicator marker, to forward the second payload indicator marker, and to forward the second payload;
a monitor circuit to measure a time delay between the first payload indicator marker and the second payload indicator marker and to adjust one of the first or second elastic buffer control circuits by the measured time delay to align the first payload indicator marker and the second payload indicator marker with each other;
a multiplexer to receive the first payload and the second payload, to select between the first payload and the second payload, and to forward a selected payload;
and
a pointer generator to receive the selected payload, to generate a third overhead and a third payload indicator, and to include the third overhead and third payload indicator with the selected payload to create a third digital signal with a third payload identical to the first and second payloads.

5 more elements

A method for processing digital signals in a telecommunications system that allows hit-less switching between a first digital signal, in which a first payload, a first payload indicator marker and a first overhead are transported on a first channel, and a second digital signal, in which a second payload identical to the first payload, a second payload indicator marker and a second overhead are transported on a second channel, comprising:

receiving the first signal at a first pointer follower, removing the first overhead, and forwarding the first payload and the first payload indicator marker;
receiving the second signal at a second pointer follower, removing the second overhead, and forwarding the second payload and the second payload indicator marker;
receiving the first payload and the first payload indicator marker at a first elastic buffer with control circuit, forwarding the first payload indicator marker, and forwarding the first payload;
receiving the second payload and the second payload indicator marker at a second elastic buffer with control circuit, forwarding the second payload indicator marker, and forwarding the second payload;
measuring a time delay between the first payload indicator marker and the second payload indicator marker at a monitor circuit and adjusting one of the first or second elastic buffer control circuits by the measured time delay to align the first payload indicator marker and the second payload indicator marker;
receiving the first payload and the second payload at a multiplexer, selecting between the first payload and the second payload, and forwarding a selected payload;
and
receiving the selected payload at a pointer generator, generating a third overhead and a third payload indicator, and including the third overhead and third payload indicator with the selected payload to create a third digital signal with a third payload identical to the first and second payloads.

5 more elements

Dependencies are inferred from the claim text.