Internal fail-open
Some Sensor models provide fail-open through their in-built copper ports. Sensor models that provide in-built fail-open are:
- M-Series: M-2950, M-2850, M1450, and M-1250,
- NS-series: NS9500, NS9300, NS9200, NS9100, NS7500, NS7350, NS7250, NS7150, NS7300, NS7200, NS7100, NS5200, NS5100, NS3500, NS3200, and NS3100
External fail-open
Fail-open switches are categorized in several ways. One categorization, as have seen above, is based on functionality – active or passive. In addition, they are also categorized based on the type of ports and the corresponding type of cables that connect them to the Sensor and network device – copper or fiber. Copper and fiber fail-open switches are further categorized based on the maximum throughput that each model supports. Finally, every fail-open switch optionally has the facility to trigger alarms and send notifications to an SNMP manager.
Important
While choosing a fail-open switch, you must remember that certain fail-open switches are compatible only with certain Sensors. The comparison in the tables in upcoming sections provide details about which fail-open switches work with which Sensors. These tables contain a Model no. for each fail-open switch. The rest of the chapter frequently refers to the Model no. of each fail-open kit when explaining steps to perform various functions.
Important
All active fail-open switches support SNMP traps regardless of whether the switch is copper or fiber. The switch in such fail-open kits consists of a Management port. This allows you to assign an IP address to the fail-open switch and establish communication with an SNMP server through the network.
Fiber fail-open switches consist of two types: single mode and multi-mode fibers. The table below gives you some relevant details about both types of fiber optic fail-open switches. This is especially relevant because you must determine the type of fiber that is used your organization network before you decide which type of fail-open switch to use. Also, all product documentation for fail-open kits and decals on the fail-open switches will repeatedly refer to these parameters.
| Type | Fiber thickness | Wavelength range |
|---|---|---|
| Single mode (Long reach) | 8.5 µm | 1300 nm to 1550 nm |
| Multi-mode (Short reach) | 50 µm or 62.5 µm | 850 nm to 1300 nm |
Support for External Active Fail-Open Kits in Sensors with internal fail-open functionality
All Sensor port-pairs with internal or in-built fail-open functionality (except M-1250 and M-1450 ) can also support active fail-open kits (refer to the section Active fail-open switches for compatibility information). For additional details, refer to the specific fail-open kit guides.
Using an external (active) fail-open switch has the following advantages over the in-built mode:
- Lower latency in a bypass mechanism
- Elimination of risk associated with a single point of failure