Configuring Forced Port Link-up
The Ethernet standard requires a port to have an active RX connection to a peer device to be able to negotiate link parameters (for example, for auto-negotiation purposes) before the port can be brought into up state.
In some special cases, though, (for example for security purposes) using both RX/TX wire connections/fiber strands in a port is not required when only unidirectional connectivity is being used: in such cases, in fact, only the RX wire connections/fiber strand are expected to receive traffic from the TX of the peer device (whose RX is unused). This unidirectionality is expected when one peer port is supposed to only receive traffic and the other one is supposed to only transmit it. However, in normal circumstances, connecting only the RX on one port to the TX on the other would not generate a link-up on the latter.
Starting from Netvisor ONE version 5.2.0, it is possible to configure a port to be forced to be up even when its RX connector/fiber is not connected to any peer device by using the port-force-linkup-add command like so:
CLI (network-admin@leaf1) > port-force-linkup-add ports 39
CLI (network-admin@leaf1) > port-force-linkup-show
switch: leaf1
leaf1: Ports enabled for force linkup: 39
CLI (network-admin@leaf1) > port-xcvr-show port 39
switch port vendor-name part-number serial-number temp[C] vcc33[V] tx-bias[mA] tx-pwr[dBm] rx-pwr[dBm]
-------- ---- ---------------- ----------- ---------------- ------- -------- ----------- ----------- -----------
leaf1 39 AVAGO AFBR-709SMZ AD1410307JT 22.75 3.31 6.35 -2.29 -40.00
CLI (network-admin@leaf1) > port-show port 39
switch port bezel-port status config
-------- ---- ---------- ---------- ------
leaf1 39 39 up,vlan-up fd,10g
Port 39 above has no RX connection, but with this configuration the software is able to force the port in up state.
This configuration can be disabled with the following command:
CLI (network-admin@leaf1) > port-force-linkup-remove ports 39
Note: Please note that this capability is hardware dependent and may not be available with all ASICs.