Contents
What is UDLD loop?
Unidirectional Link Detection (UDLD) is a Cisco proprietary layer 2 protocol used to determine the physical status of a link. UDLD helps to prevent forwarding loops and blackholing of traffic by identifying and acting on logical one-way links that would otherwise go undetected.
What does UDLD port aggressive do?
With UDLD aggressive mode enabled, when a port on a bidirectional link that has a UDLD neighbor relationship established stops receiving UDLD packets, UDLD tries to reestablish the connection with the neighbor. After eight failed retries, the port is disabled.
How do I enable loop guard?
Issue this command in order to enable loop guard globally:
- CatOS Console> (enable) set spantree global-default loopguard enable.
- Cisco IOS Router(config)#spanning-tree loopguard default.
What happens when UDLD detects a Tx-Rx loop?
When a Tx-Rx loop is detected, UDLD performs these actions: These syslog messages are then generated: is down (Error disabled. Reason:UDLD Tx-Rx Loop) is down (Error disabled. Reason:UDLD Tx-Rx Loop)
Is there a problem with the UDLD loop?
UDLD Loop issue? Our department lan is a collection of HP switches, one of which is connected by 10G fiber to a Cisco switch that is our gateway to the campus network. Today the Cisco switch shut down our with the UDLD loop error below. This has been working for many months, so I’m trying to understand the sudden error.
What is the error message for udld-3-disable?
UDLD-3-DISABLE: Unidirectional link detected on port 3/2. Port disabled. (CatOS) PM-SP-4-ERR_DISABLE: udld error detected on Gi4/1, putting Gi4/1 in err-disable state. (Cisco IOS system software) The port shutdown by UDLD remains disabled until it is manually re-enabled, or until the errdisable timeout expires (if configured).
How to troubleshoot uni-directional link Detection ( UDLD ) errors?
This document describes how to troubleshoot Uni-Directional Link Detection (UDLD) error messages on a Cisco Nexus 7000 Series switch. Cisco recommends that you have a basic knowledge of these topics: The information in this document is based on these software and hardware versions: