Appendix C: Programming Generation 3 Lan Bypass - Lanner NCA-4210 User Manual

Network Computing Platforms
Appendix C: Programming Generation 3
LAN Bypass
The bypass function is used to link two independent Ethernet ports when the system crashes
or powers off. This means if your system is equipped with a LAN Bypass function, a condition
in your system will not interrupt your network traffic. Different from the previous two
generations (Gen1 and Gen2), the Lanner Bypass Gen 3 employs a programming method to
control the bypass function by software. There are typically two communication status for the
bypass function, one is "Normal" and another is "Bypass" status. Furthermore, the Lanner
Bypass software is capable to control the bypass status in the following 3 instances.
1. When the system powers off, it can be forced to enable the LAN Bypass function.
2. When the system is in the just-on state which is a brief moment when it powers up.
3. When the system is running
Please refer to the LAN_Bypass_Watchdog folder on the Driver and Manual CD.
Lanner bypass possess the following features:
1. Communication through SMBUS (I2C)
2. Independent bypass status control for each pair up to a total of 4 pairs
3. Lanner Bypass Modules can bypass systems Ethernet ports on a host system during three
instances: Just-on (Just-on is the brief moment when the internal power supply turns on and
booting process starts), System off, or upon software request (during run-time).
4. Software programmable bypass or normal mode
5. Software programmable timer interval:
- JUST-ON watchdog timer, used during JUST-ON, has timer setting of 5~1275 seconds of
timer interval.
- Run-Time watchdog timer, used during run-time, has setting of 1~255 seconds of timer
interval.
6. Multiple Watchdog Timers:
-Two for run-time: It is designed to give you a more variety of controls of the bypass on port
basis. By using dedicated watchdogs for different pairs of bypass, you have the flexibility to
manage the bypass status for them differently.
-One for just-on: It is designed to give you the precise control of the bypass during this phase.
You can use this timer to delay enabling the bypass in just-on state.
For sample LAN bypass code and the Bypass Manual, see the LAN_Bypass folder on the
Driver and Manual CD or the Lanner Support Website at