Cisco Systems PA-POS-2OC3 manual Interface Specifications, OC-3 Optical Fiber Specifications

Chapter 1 PA-POS-1OC3 Overview

Interface Specifications

Interface Specifications

The physical layer interface for the PA-POS-1OC3 is Optical Carrier-3 (OC-3c), the specification for SONET STS-3c and SDH STM-1 transmission rates, and the PA-POS-1OC3 is designed to comply with Packet-over-SONET specifications. The PA-POS-1OC3 provides one 155.520-Mbps packet OC-3 network interface for all supported platforms.

The PA-POS-1OC3 has a duplex LC-type receptacle that allows connection to single-mode or multimode optical fiber. (For more information on the optical fiber cables you should use with this port adapter, see the “Cables and Connectors” section on page 1-7.)

Packet data is transported using Point-to-Point Protocol (PPP) and is mapped into the STS-3c/STM-1 frame. The encapsulations used add approximately half the number of bytes of transport overhead as that involved with ATM using ATM Adaptation Layer 5 (AAL5) and line card control (LCC) Subnetwork Access Protocol (SNAP) encapsulations.

The PA-POS-1OC3 interface is compliant with RFC 1619, PPP over SONET/SDH, and RFC 1662, PPP in HDLC-like Framing. The PA-POS-1OC3 supports RFC 1619 PPP over SONET/SDH encapsulation, and provides support for SNMP agent v1 (RFC 1155–1157), and Management Information Base (MIB) II (RFC 1213).

OC-3 Optical Fiber Specifications

The OC-3 specification for optical fiber transmission defines two types of fiber: single-mode and

multimode. Within the single-mode category, two types of transmission are defined: intermediate reach and long reach. Within the multimode category, only short reach is available.

Modes can be thought of as bundles of light rays entering the fiber at a particular angle. Single-mode fiber allows only one mode of light to propagate through the fiber, and multimode fiber allows multiple modes of light to propagate through the fiber.

Multiple modes of light propagating through the fiber travel different distances depending on the entry angles, which causes them to arrive at the destination at different times (a phenomenon called modal dispersion); therefore, single-mode fiber is capable of higher bandwidth and greater cable run distances than multimode fiber. Table 1-1lists nominal OC-3 optical parameters for single-mode and multimode optical fiber transmission.

Note If the distance between two connected stations is greater than the maximum distances listed, significant signal loss can result, making transmission unreliable.

PA-POS-1OC3 Single-Port Port Adapter Installation and Configuration Guide

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