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Chapter 5: Operation
5.4 Ethernet Switching (SW1046A)
A/B Switch models (SW1046A) that support Ethernet remote control can be switched using commands sent over an Ethernet net-
work. In order to use the Ethernet Network port on the A/B Switch you must set the IPADDRESS, SUBNETMASK, and GATEWAY
address parameters before connecting to your network. See Section 6 for more details on how to do this. After setting up the
system and powering up for the first time, you may also need to change other parameters for your application. All configuration
parameters are stored in non-volatile memory. They are immediately active when a change is made, but they will not become per-
manent until the SAVE command, followed by the RESET command has been executed.
Once the Ethernet remote control port has been configured, the A/B Switch can be switched using SNMP commands—see the
MIB path summary in the appendix for a list of SNMP variables and their functions.
The A/B Switch also supports remote telnet access, and can be controlled via a telnet session using the same commands as
supported by the RS-232 serial interface. Refer to Section 7 for the complete list of console commands.
As an additional option, A/B Switch models that support Ethernet remote control also include a built-in http server application
that allows all of the console commands listed in section 7 to be accessed via a web browser interface. See Section 8 for more
details about the web browser interface feature.
NOTE: The NETWORK port on the A/B Switch is 10BASE-T only. The STATUS LED will blink whenever the A/B Switch receives a
command from the Ethernet network interface or from the serial RS232 interface. In addition the STATUS LED will blink
when a switching command is issued via the remote control contacts or front panel push button switches.
The A/B Switch also has the ability to issue either SNMP traps, or UDP syslog messages. These messages can be sent to one or
more network administrator systems to provide notification when the A/B Switch changes connection states either automatically
(auto bypass switching or auto recovery switching) or via manual control (front panel toggle switch or commands received on the
RS232 or Ethernet interfaces), and when certain other events occur. See Section 10 and Section 11 for additional details.
To restrict access to the A/B Switch, each of the Ethernet interface options (SNMP, telnet, and web browser) can be independently
enabled/disabled, and if enabled, can be configured to require a login password. Additionally, user access can be restricted by IP
address so only commands received from pre-defined “administrator” IP addresses will be acknowledged and acted upon. See
section 7 for additional information regarding these commands.
5.5 Automatic Switching
The A/B Switch models that support Ethernet remote control can also be configured to automatically switch between a “normal”
connection state (port C connected to port B) and a “bypass” or “failover” connection state (port C connected to port A). User
configurable failover and recovery parameters control the auto-switching functions to allow the switch to be used in a variety of
applications. In order to be able to perform the auto bypass and auto recovery switching functions, the A/B Switch issues ICMP
echo request (PING) packets from its Ethernet network interface to a user configurable IP address on the network. If the “normal”
network path connections between the A/B Switch and the device being monitored go down for any reason, the A/B Switch will
no longer be able to PING the specified IP address, and will then automatically switch from the “normal” connection state (port C
connected to port B) to the “bypass” or “failover” connection state (port C connected to port A). Once the problems on the
primary path have been identified and corrected, the user can issue a command to cause the A/B Switch to switch from the
failover connection state back to the normal connection state. If auto recovery is enabled, the A/B Switch will automatically
re-connect the normal path connections when it is again able to PING the user specified IP address. When using the auto
recovery feature, make sure that the Ethernet network port on the A/B Switch is connected to the user’s network so that the
normal path is continuously being monitored even when the backup path has been selected; otherwise, the A/B Switch could
repeatedly switch (flap) back and forth between the failed primary path and the functioning backup path. See Figures 5-1 and
5-2 for examples of auto switching configurations.
