ACX7020 Network Cable and Transceiver Planning
Learn about power requirement and supported operating temperature for transceivers, fiber-optic cables you can use, and cable connector details.
Determining Transceiver Support for ACX7020 Routers
You can use the Hardware Compatibility Tool to find information about the pluggable transceivers and connector types supported by your Juniper Networks device. The tool also documents the optical and cable characteristics, where applicable, for each transceiver. You can search for transceivers by product—and the tool displays all the transceivers supported on that device—or by category, interface speed, or type. You can find the list of supported transceivers for the ACX7020 at https://apps.juniper.net/hct/product/.
If you face a problem running a Juniper Networks device that uses a third-party optic or cable, the Juniper Networks Technical Assistance Center (JTAC) can help you diagnose the source of the problem. Your JTAC engineer might recommend that you check the third-party optic or cable and potentially replace it with an equivalent Juniper Networks optic or cable that is qualified for the device.
The I-temp and C-temp transceivers on ACX7020 support the following ambient temperature values:
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I-temp SFP, SFP+, and SFP28 transceivers up to 2 W in full working temperature range (–40 °C to 70 °C)
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C-temp SFP, SFP+, and SFP28 transceivers up to 1.4 W in maximum working temperature range (0 °C to 55 °C)
Cable and Connector Specifications for ACX7020 Routers
The transceivers that an ACX7020 device supports use fiber-optic cables and connectors. The type of connector and the type of fiber depend on the transceiver type.
You can determine the supported cables and connectors for your specific transceiver by using the Hardware Compatibility Tool.
To maintain agency approvals, you must use only a properly constructed, shielded cable.
The terms multifiber push-on (MPO) and multifiber termination push-on (MTP) describe the same connector type. The rest of this topic uses MPO to mean MPO or MTP.
LC Duplex Connectors
You can use patch cables with LC duplex connectors to connect two supported transceivers of the same type—for example, 40GBASE-LR4 to 40GBASE-LR4 or 100GBASE-LR4 to 100GBASE-LR4. A patch cable is one fiber pair with two LC duplex connectors at opposite ends. LC duplex connectors are also used with 12-fiber ribbon breakout cables.
Calculate Power Budget and Power Margin for Fiber-Optic Cables
Use the information in this topic and the specifications for your optical interface to calculate the power budget and power margin for fiber-optic cables.
You can use the Hardware Compatibility Tool to find information about the pluggable transceivers supported on your Juniper Networks device.
To calculate the power budget and power margin, perform the following tasks:
Calculate Power Budget for Fiber-Optic Cables
To ensure that fiber-optic connections have sufficient power for correct operation, you need to calculate the link's power budget (PB), which is the maximum amount of power it can transmit. When you calculate the power budget, you use a worst-case analysis to provide a margin of error, even though all the parts of an actual system do not operate at the worst-case levels. To calculate the worst-case estimate of PB, you assume minimum transmitter power (PT) and minimum receiver sensitivity (PR):
PB = PT – PR
The following hypothetical power budget equation uses values measured in decibels (dB) and decibels referred to one milliwatt (dBm):
PB = PT – PR
PB = –15 dBm – (–28 dBm)
PB = 13 dB
How to Calculate Power Margin for Fiber-Optic Cables
After calculating a link's PB, you can calculate the power margin (PM), which represents the amount of power available after subtracting attenuation or link loss (LL) from the PB. A worst-case estimate of PM assumes maximum LL:
PM = PB – LL
PM greater than zero indicates that the power budget is sufficient to operate the receiver.
Factors that can cause link loss include higher-order mode losses, modal and chromatic dispersion, connectors, splices, and fiber attenuation. Table 1 lists an estimated amount of loss for the factors used in the following sample calculations. For information about the actual amount of signal loss caused by equipment and other factors, refer to vendor documentation.
Link-Loss Factor |
Estimated Link-Loss Value |
|---|---|
Higher-order mode losses |
Single mode—None Multimode—0.5 dB |
Modal and chromatic dispersion |
Single mode—None Multimode—None, if product of bandwidth and distance is less than 500 MHz-km |
Faulty connector |
0.5 dB |
Splice |
0.5 dB |
Fiber attenuation |
Single mode—0.5 dB/km Multimode—1 dB/km |
The following sample calculation for a 2-km-long multimode link with a PB of 13 dB uses the estimated values from Table 1. This example calculates LL as the sum of fiber attenuation (2 km @ 1 dB/km, or 2 dB) and loss for five connectors (0.5 dB per connector, or 2.5 dB) and two splices (0.5 dB per splice, or 1 dB) as well as higher-order mode losses (0.5 dB). The PM is calculated as follows:
PM = PB – LL
PM = 13 dB – 2 km (1 dB/km) – 5 (0.5 dB) – 2 (0.5 dB) – 0.5 dB
PM = 13 dB – 2 dB – 2.5 dB – 1 dB – 0.5 dB
PM = 7 dB
The following sample calculation for an 8-km-long single-mode link with a PB of 13 dB uses the estimated values from Table 1. This example calculates LL as the sum of fiber attenuation (8 km @ 0.5 dB/km, or 4 dB) and loss for seven connectors (0.5 dB per connector, or 3.5 dB). The PM is calculated as follows:
PM = PB – LL
PM = 13 dB – 8 km (0.5 dB/km) – 7(0.5 dB)
PM = 13 dB – 4 dB – 3.5 dB
PM = 5.5 dB
In both the examples, the calculated PM is greater than zero, indicating that the link has sufficient power for transmission and does not exceed the maximum receiver input power.