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ULDP Function Configuration
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Interface Converter) or interfaces have problems, software problems, hardware becomes
unavailable or operates abnormally. Unidirectional link will cause a series of problems,
such as spinning tree topological loop, broadcast black hole.
ULDP (Unidirectional Link Detection Protocol) can help avoid disasters that could
happen in the situations mentioned above. In a switch connected via fibers or copper
Ethernet line (like ultra five-kind twisted pair), ULDP can monitor the link state of physical
links. Whenever a unidirectional link is discovered, it will send warnings to users and can
disable the port automatically or manually according to users‘ configuration.
The ULDP of switches recognizes remote devices and check the correctness of link
connections via interacting ULDP messages. When ULDP is enabled on a port, protocol
state machine will be started, which means different types of messages will be sent at
different states of the state machine to check the connection state of the link by
exchanging information with remote devices. ULDP can dynamically study the interval at
which the remote device sends notification messages and adjust the local TTL (time to live)
according to that interval. Besides, ULDP provides the reset mechanism, when the port is
disabled by ULDP, it can check again through reset mechanism. The time intervals of
notification messages and reset in ULDP can be configured by users, so that ULDP can
respond faster to connection errors in different network environments.
The premise of ULDP working normally is that link works in duplex mode, which
means ULDP is enabled on both ends of the link, using the same method of authentication
and password.
8.2
ULDP Configuration Task Sequence
1. Enable ULDP function globally
2. Enable ULDP function on a port
3. Configure aggressive mode globally
4. Configure aggressive mode on a port
5. Configure the method to shut down unidirectional link
6. Configure the interval of Hello messages
7. Configure the interval of Recovery
8. Reset the port shut down by ULDP
9. Display and debug the relative information of ULDP
1. Enable ULDP function globally
Command
Explanation
Global configuration mode