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Chapter 1
Overview
Each OC12 POS line card has one pair of SC-type fiber receptacles to allow connection to single-mode
optical fiber. (For more information on the optical fiber cables you should use with this line card, see
the
Connectors" section on page
Packet data is transported using Point-to-Point Protocol (PPP) and is mapped into the STS-12c/STM-4
frame. (RFC-1619)
The management of the OC12 POS line card interface is compliant with RFC 1595.
OC12 POS Line Card Optical Fiber Specifications
The OC12 POS line card specification for optical fiber transmission is single-mode.
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.
transmission.
Note
If the distance between two connected stations is greater than the maximum distances listed, significant
signal loss can result, making transmission unreliable.
Table 1-1
Table 1-1
OC-12 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
Multimode
–20 dBm min.
short reach
to –14 dBm max.
at 1280–1335 nm
1. This table gives nominal OC-12 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).
OL-3437-01
"OC12 POS Line Card Optical Fiber Specifications" section on page 1-5
1-8.)
Table 1-1
lists the OC-12 optical parameters.
Maximum Power
to Receiver
–10 dBm
4
–8 dBm
4
–8 dBm
4
lists nominal OC-12 optical parameters for single-mode optical fiber
Receiver
2
Sensitivity
–34 dBm
–31 dBm
–30 dBm
OC12 Packet Over SONET Line Card Installation and Configuration
OC12 POS Line Card Optical Fiber Specifications
and the
"Cables and
Loss
Nominal Distance
Budgets
Between Stations
10 to 28 dB
Up to 25 mi. (40 km)
0 to 12 dB
Up to 9 mi. (15 km)
0 to 7 dB
Up to 1.2 mi. (2 km)
1-5
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