Cabletron Systems CSX200, CSX400 Path Terminating Equipment FE100-Sx or APIM-2x, 4-77, Bridging

Bridging

These errors can occur in any of the four optical layers of a SONET network, which are (in order from lowest to highest layer in the hierarchy) the physical Medium, Section, Line, and Path layers.

¥The Medium layer is the Photonic layer that physically converts electrical signals to optical signals.

¥The Section layer deals with the transport of frames across the optical medium, including framing and scrambling data for transmission, the error monitoring and maintenance between section-layer elements (such as signal regenerators/repeaters), and orderwire (provisioning channels).

¥The Line layer is responsible for reliably transporting the higher-level Path layer payload and overhead across the physical medium. It is responsible for synchronizing (clocking) the data transmission, multiplexing signals into a single channel, error monitoring and maintenance between line-layer elements (such as Add/Drop Multiplexers), and switching to secondary data paths should the primary path experience failure.

¥The Path layer transports services between path-terminating equipment.

It maps signals into a format required by the line layer, and reads, interprets, and modiÞes path overhead for performance monitoring and automatic protection switching.

Error reporting occurs at the Section, Line, and Path layers, and is carried within the corresponding SONET overhead. In terms of the SONET protocol stack, the three layers with overhead are mapped to the SONET link as shown in the following diagram.

The statistics and errors indicators provided in the SONET/SDH statistics window are taken from both the end-to-end Path layer, and from the Section layer between the FE100-Sx or APIM-2x and the Add/Drop Multiplexer to which it is connected. They reßect errors that may be occurring on your customer premises equipment, as well as errors that may be occurring at the Line or Section layers within the SONET MAN/WAN ring itself.

Path-

Terminating

Equipment—

(FE100-Sx

or APIM-2x)

Line-

Terminating

OC-3c Equipment—

link Telco/SP ADM (Add/Drop Multiplexer)

Regenerators

Section

Line

Path

Line-

Terminating

Equipment—

Telco/SP ADM

(Add/Drop

Multiplexer)

Path-

OC-3c Terminating link Equipment— (FE100-Sx or APIM-2x)

SONET Port Configuration 4-77