10.6.4. Redundant LAN Interface 
IMPORTANT:
Only possible if HG 3500 is configured without
WAML function!
Feature requirement
For increased resilience, HG 3500 and HG 3575 boards should be connected
with two LAN cables to different switches.
Feature functionality
- Board is starting up:
-
If both LAN cables are connected and the HG board is starting up, LAN port 1 will always be activated.LAN port 2 will be on , only layer 1 is active (higher protocol layers are down).If only one LAN port is connected when the board is starting up (LAN1 or LAN2), that port will be used.
- If the active LAN port is disconnected/disabled by peer or equipment (when
both LAN ports are connected):
- The boards activate the LAN port.
- The “new” port sends a GRATUITOUS ARP with the same MAC and IP addresses as the “old” port (the second MAC address will only be used if also another feature is configured at the interface (WAML/PPP router)).
- When the board switches ports, the payload will be lost for < 2 sec – all active connections will be saved and NOT disconnected.
- The port switch will be logged via OpenScape-4000-F message in HISTA.
- If the “old” port comes up again, no port switchback will be performed.
Restriction
If the board is configured with FUNCTION=WAML in the AMO BFDAT, LAN
port 1 is unable to switch over to LAN port 2 in the event of a fault.
This is because the feature WAML2/WAML Replacement is used for signaling
survivability. This prevents the STMI board used from even operating
redundant LAN interfaces.
Notes
- The boards only have one IP and MAC address.
- Only one port is active at a time.
- When the board starts up with two connected ports, LAN1 will be activated.
- No port switchback will be performed.
- No configuration in OpenScape 4000 / HG boards is necessary to activate the feature.
- After installation of redundant LAN feature it is recommended to verify the functionality. The test can be performed by unplug the active LAN cable for at least 5 seconds and observe the switchover. The reason for the test is to verify the correct behavior of HG3500 in interaction with redundant IT/LAN infrastructure (e.g. L2 Switches/Router).
- Even if a separate management LAN is configured, LAN redundancy can still be used on STMIX/STMIY if VLANs are used