Port Management
UDLD
Cisco Sx350, SG350X, SG350XG, Sx550X & SG550XG Series Managed Switches, Firmware Release 2.2.5.x 156
9
UDLD States and Modes
Under the UDLD protocol, ports are assigned the following states:
• Detection—System is attempting to determine whether the link is bidirectional or
unidirectional. This is a temporary state.
• Bidirectional—Traffic sent by a local device is known to be received by its neighbor,
and traffic from the neighbor is received by the local device.
• Shutdown—The link is unidirectional. Traffic sent by a local device is received by its
neighbor, but traffic from the neighbor is not received by the local device.
• Undetermined—The system cannot determine the state of the port, because one of the
following is occurring:
- The neighbor does not support UDLD.
or
- The neighbor does not receive traffic from the local device.
The UDLD action in this case depends on the UDLD mode of the device as explained
below.
UDLD supports the following modes of operation:
• Normal
If the link state of the port is determined to be bi-directional and the UDLD
information times out while the link on the port is still up, UDLD tries to re-establish
the state of the port.
• Aggressive
If the link state of the port is determined bi-directional and the UDLD information
times out, UDLD shuts down the port after an extended period of time, when it can
determine that the link is faulty. The port state for UDLD is marked as undetermined.
UDLD is enabled on a port when one of the following occurs:
• The port is a fiber port and UDLD is enabled globally.
• The port is a copper port and you specifically enable UDLD on it.
How UDLD Works
When UDLD is enabled on a port, the following actions are performed:
• UDLD initiates the detection state on the port.
To Next Page
Loading...
Need help?
General
