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The SRX-SFP-1GE-SX is a Gigabit standard short-range multimode optical module defined and introduced by Juniper Networks. It adheres to the 1000BASE-SX international standard and is primarily used in Juniper’s SRX series firewalls/business gateways (such as SRX340, SRX550, SRX1500, SRX5600, etc.) as well as some compatible switch/router devices.
SRX-SFP-1GE-SX Datasheet
| Model | SRX-SFP-1GE-SX | Juniper’s official part number is usually 740-011613 |
| Package form | SFP | 1G Mini-GBIC |
| Transmission rate | 1G Mini-GBIC | Gigabit Ethernet |
| Center wavelength | 850nm | Using VCSEL lasers with lower safety categories, low cost, only suitable for multimode fiber |
| Interface type | Duplex LC | Need two optical fibers (one transmitter and one receiver) |
| Transmission fiber and distance | MMF | OM2 fiber optic: capable of transmitting up to 550 meters. |
Naming Rule
| SRX | – | SFP | – | 1GE | – | SX |
| Representing Juniper’s official designated module compatibility coding for the SRX security gateway/firewall series. | Small form factor pluggable | 1 Gigabit Ethernet (1000Mbps) | Short Range (850nm) |
In addition to the SRX-SFP-1GE-SX mentioned above, Juniper Networks also has several other gigabit SFP optical modules (electrical port modules) specifically designed for high SRX system firewalls/security gateways, such as SRX SFP 1GE LH, SRX SFP 1GE LX, and SRX SFP 1GE T, which are suitable for completely different transmission media and distances.
The following is a detailed disassembly of these three modules:
SRX-SFP-1GE-LX:Gigabit Single Multi Mode Medium Short Range Optical Module
LX stands for Long Reach, which is a single-mode optical module specifically designed for enterprise LAN/SAN networks, data centers, and ISP networks for long, medium, and short distance connections.
- Transmission medium: Single mode fiber (SMF), 9/125 µ m.
- Center wavelength: 1310nm.
- Transmission distance: up to 10km.
- Interface type: LC Duplex.
- Applicable scenarios: Gigabit low latency link docking between different data center data centers (DCs) within the same city, or connecting the main data center to a disaster recovery room several kilometers away; Enterprise customers are provided with dedicated line access (Gigabit Ethernet Premium Link) and remote out of band management network (Out of Band Management) setup.
SRX-1GE-LH: Gigabit Single Mode Ultra Long Range Optical Module
LH stands for Long Haul. This is a single-mode optical module specifically designed for long-distance connections across buildings, parks, or metropolitan area networks.
- Transmission medium: Single mode fiber (SMF), 9/125 µ m.
- Center wavelength: 1550nm (this wavelength has extremely low attenuation in single-mode fibers and is suitable for ultra long distance transmission).
- Transmission distance: up to 70 km or 80 km (depending on the specific batch of laser power).
- Interface type: LC Duplex.
- Applicable scenarios: Enterprise headquarters are interconnected with branch networks tens of km away, or connected to the backbone equipment of remote operators’ metropolitan area networks.
- Attention: Due to its strong emission power, if it is used for close range (such as several meters to several hundred meters) experimental testing, an optical attenuator must be installed at the receiving end, otherwise it is very easy to burn out the receiver of the opposite end optical module.
SRX-SFP-1GE-T: Gigabit electrical port module (RJ45 adapter module)
T represents Twisted Pair (twisted pair/copper cable). Strictly speaking, it is not an “optical” module, but an electrical interface module (also known as an optical to electrical module). Its function is to transform the SFP optical port on the switch or firewall into a regular RJ45 Ethernet interface.
- Transmission medium: ordinary Ethernet/copper cables (Cat5e/Cat6/Cat6a cable).
- Transmission distance: up to 100m (limited by the standard limitations of traditional Ethernet copper cables).
- Interface type: RJ45 interface (which is the most common computer network cable socket).
- Applicable scenario: When the built-in electrical port (Ethernet port) on your Juniper SRX firewall is not enough, but the optical port (SFP slot) is still empty, and you need to connect to a server or local switch that is very close and only has Ethernet ports, plugging in this module can directly plug in the Ethernet cable for use.
Juniper SRX Gigabit Family
In order to better compare the four modules, we have compiled a table as follows:
| Juniper model | Transmission medium | Interface | Wavelength | Max. Distance | Application |
| SRX-SFP-1GE-SX | MMF | Duplex LC | 850nm | 550m | Office Building Same Computer Room/Same Floor Backbone Interconnection |
| SRX-SFP-1GE-LX | SMF | Duplex LC | 1310nm | 10km | Same city cross data center or enterprise network dedicated line access |
| SRX-SFP-1GE-LH | SMF | Duplex LC | 1550nm | 70-80km | Connecting across long-distance regions and metropolitan area networks |
| SRX-SFP-1GE-T | Copper twisted pair | RJ45 | Copper Cable C at6 | 100m | Convert optical port to electrical port, connect to local server |
How to choose between them?
1. Hardware compatibility: Although these are Juniper standard components, in actual engineering, users often use third-party compatible brands such as the SFP-1.25G-SX optical module provided by YINGDA. We will write the same manufacturer identification code before leaving the factory, which not only ensures 100% stable operation in Juniper’s firewalls, switches, and routers, but also significantly reduces expansion costs. If the compatibility code is not written, inserting the SRX firewall may result in an error message and reject the work (indicating unsupported transceiver). You can use the Juniper command line to enter ‘show chassis hardware’ to see if these modules are properly recognized by the system as NON-JNPR (third-party compatible) or REV (factory version).
2. Both ends must be paired: If one end of your fiber is plugged into this SX (850nm) module, the other end of the fiber must also be plugged into the 850nm SX module on the switch. It absolutely cannot be directly docked with modules of 1310nm and 2km, otherwise the wavelength will not match and the optical path will not be connected.
3. Support DDM (Digital Diagnosis): Most compatible versions provide DOM/DDM support, which allows real-time viewing of the received and emitted light power through the Juniper command line show chassis hardware or show interfaces diagnostics option. It is very practical for troubleshooting short distance fiber link faults inside enterprise data centers.
4. Range of receiving power: Its overload point (maximum receiving power) is usually around -3 dBm, and the receiving sensitivity is around -20 dBm. If a link is found to be blocked on the Juniper firewall, you can enter the command line show interfaces diagnostics option ge-0/0/x to check if the real-time transmit/receive power is within this range.
5. Temperature range: If you are deploying in harsh and variable environments (such as outdoor chassis, industrial automation workshops), it is recommended to choose a model with the suffix “-ET” (SRX-SFP-1GE-LX-ET), which supports industrial grade wide temperature working environments from -40℃ to 85℃.
Can they connect to multimode optical fibers? (Special case)
According to the IEEE 800BASE-LX standard, modules such as SRX-SFP-1GE-LX can be connected to multimode fibers (OM1/OM2/OM3/OM4) under extremely harsh conditions, but there are significant limitations:
① Special fiber patch cords must be used: multi-mode patch cords cannot be directly plugged in. You must add a Mode Conditioning Patch Cable (MCP) between the module and the multimode fiber.
② The transmission distance is significantly reduced: even with MCP path cables, the transmission distance drops sharply from 10 km to around 550 m.
③ Not recommended for modern networks: This approach was designed early on to be compatible with outdated multimode fiber optic cabling. In today’s gigabit and 10 gigabit networks, almost no one deploys like this anymore, as it can easily cause link instability.
Yingda can provide fiber optical modules compatible with Juniper’s series. Any requirements, please feel free to contact us for quotation.
