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OC-3 Optical Fiber Specifications
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-2OC3 interface is compliant with RFC 1619, PPP over SONET/SDH, and RFC 1662, PPP
in HDLC-like Framing. The PA-POS-2OC3 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.
optical fiber transmission.
If the distance between two connected stations is greater than the maximum distances listed, significant
Note
signal loss can result, making transmission unreliable.
Table 1-1
Table 1-1
OC-3 Optical Parameters
Transceiver
Transmit
1
Type
Power
3
Single-mode
–5 dBm min.
long reach
to 0 dBm max.
at 1280–1335 nm
5
Single-mode
–15 dBm min.
intermediate reach
to –8 dBm max.
at 1280–1335 nm
6
Multimode
–20 dBm min.
short reach
to –14 dBm max.
at 1280–1335 nm
1. This table gives nominal OC-3 optical parameters.
2. This value represents the maximum power to which any receiver can be exposed.
3. Complies with Bellcore GR-253-CORE Long Reach Specification (LR-1).
4. Nominal wavelength is 1310 nm.
5. Complies with Bellcore GR-253-CORE Intermediate Reach Specification (IR-1).
6. Complies with Short-Reach OC-3 Specification SR-OC-3.
PA-POS-2OC3 Two-Port Packet-over-SONET Port Adapter Installation and Configuration
1-4
Table 1-1
lists nominal OC-3 optical parameters for single-mode and multimode
lists the OC-3 optical parameters.
Maximum Power
2
to Receiver
, dBm
–10
4
–8
4
–8
4
Receiver
Loss
Sensitivity, dBm
Budgets, dB
–34
10 to 28
–28
0 to 12
–30
0 to 7
Chapter 1
Overview
Nominal Distance
Between Stations
Up to 25 mi (40 km)
Up to 9 mi (15 km)
Up to 1.2 mi (2 km)
OL-3028-06
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