Udld; Port Settings; Cli Configurations - Tripp Lite NGI-M08POE8-L2 Owner's Manual

6.15 UDLD

The UDLD (UniDirectional Link Detection) protocol is used to detect and/or disable
unidirectional connections before they create dangerous situations such as Spanning Tree loops
or other protocol malfunctions.
The UDLD protocol was implemented to help correct certain assumptions made by other
protocols and in particular to help the STP to function properly so as to avoid the creation of
dangerous Layer 2 loops.
UDLD is meant to be a Layer 2 detection protocol that works on top of existing Layer 1
detection mechanisms defined by the IEEE standards.
Network systems typically check for miss wiring or unidirectional problems at the physical
layer. The physical layer defines the actual physical components such as connectors and cables.
So, physical layer only checks for open lines or port malfunctions and would not detect a miss
wired systems.
But, UDLD performs mutual neighbor identification; in addition, it performs neighbor
acknowledgement on top of the Logical Link Control (LLC) layer and thus is able to discover
logical one-way miscommunication between neighbors even when either one of PHY layer
mechanisms has deemed the transmission medium bidirectional.
6.15.1

Port Settings

6.15.1.1 CLI Configurations

Node Command
enable show udld status
enable show udld port-status
enable show udld neighbor
enable configure terminal
config udld enable
config no udld enable
config udld message interval-
time <1-90>
config udld message interval-
time reset
configure interface IFNAME
interface udld port enable
interface no udld port enable
interface udld port aggressive
interface no udld port
aggressive
Case 1: To configure UDLD on port 1 only then disable udld port configuration on all
interfaces except port 1 and enable global UDLD.
L2SWITCH#configure terminal
Description
This command displays the UDLD global settings.
This command displays the ports' settings.
This command displays the port's neighbor
information.
This command changes the node to configure node.
This command enables the global UDLD state.
This command disables the global UDLD state.
This command configures the interval time of
sending . (unit: second).
This command configures the interval time to
default value. (7 seconds)
This command enters the interface configure node.
This command enables the udld state for the specific
port.
This command disables the udld state for the
specific port.
This command configures the udld mode to
aggressive mode for the specific port.
This command configures the udld mode to normal
mode for the specific port.
238