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Routing Engine Interface Cable and Wire Specifications
53
Attenuate to Prevent Saturation at SONET/SDH PICs
SONET/SDH interfaces in the different reach classes—short reach (SR), intermediate reach
(IR), and long reach (LR)—generate different output power levels and tolerate different input
power levels. Interfaces that have a longer reach can transmit enough power to saturate the
receivers on PICs that have a shorter reach. Specifically, LR interfaces can saturate IR PICs,
and both IR and LR interfaces can saturate SR PICs. Interfaces in the same reach class can
also potentially saturate one another.
(IR), and long reach (LR)—generate different output power levels and tolerate different input
power levels. Interfaces that have a longer reach can transmit enough power to saturate the
receivers on PICs that have a shorter reach. Specifically, LR interfaces can saturate IR PICs,
and both IR and LR interfaces can saturate SR PICs. Interfaces in the same reach class can
also potentially saturate one another.
To prevent saturation, you might need to attenuate power at the PIC receiver, particularly if
you know that it has a shorter reach than the interface that is sending the signal. Determine
the amount of attenuation needed by measuring the power level at each receiver. Attenuate
the power to bring it within the allowable range; for short lengths of fiber, with fiber and
connector loss close to zero, an attenuator of 5 to 10 dB should be sufficient.
you know that it has a shorter reach than the interface that is sending the signal. Determine
the amount of attenuation needed by measuring the power level at each receiver. Attenuate
the power to bring it within the allowable range; for short lengths of fiber, with fiber and
connector loss close to zero, an attenuator of 5 to 10 dB should be sufficient.
For specifications of minimum and maximum input level (receiver sensitivity and receiver
saturation) and minimum and maximum output level (average launch power) for the
SONET/SDH PICs supported on the M40 router, see the M20 and M40 Internet Routers PIC
Guide.
saturation) and minimum and maximum output level (average launch power) for the
SONET/SDH PICs supported on the M40 router, see the M20 and M40 Internet Routers PIC
Guide.
Routing Engine Interface Cable and Wire Specifications
For management and service operations, you connect the Routing Engine to an external
console or management network through ports on the craft interface. You can also connect
the router to external alarm-reporting devices through the alarm relay contacts on the craft
interface. (For more information, see “Craft Interface” on page 17.)
console or management network through ports on the craft interface. You can also connect
the router to external alarm-reporting devices through the alarm relay contacts on the craft
interface. (For more information, see “Craft Interface” on page 17.)
Table 17 lists the specifications for the cables that connect to management ports and the
wires that connect to the alarm relay contacts.
wires that connect to the alarm relay contacts.
Table 17: Routing Engine Interface Cable and Wire Specifications
Cable Type
Cable
Specification
Specification
Cable/Wire
Supplied
Supplied
Maximum Length
Router
Receptacle
Receptacle
Routing Engine
console or
auxiliary interface
console or
auxiliary interface
RS-232 (EIA-232)
serial cable
serial cable
One 6-ft (1.83-m)
length with
DB-9/DB-9 connectors
length with
DB-9/DB-9 connectors
6 ft (1.83 m)
DB-9 male
Routing Engine
Ethernet interface
Ethernet interface
Category 5 cable or
equivalent suitable
for 100BaseT
operation
equivalent suitable
for 100BaseT
operation
One 15-ft (4.92-m)
length with
RJ-45/RJ-45
connectors
length with
RJ-45/RJ-45
connectors
328 ft (100 m)
RJ-45
autosensing
autosensing
Alarm relay
contacts
contacts
28-AWG to 14-AWG
(0.09 to 2.09 mm
(0.09 to 2.09 mm
2
)
wire
No
None
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