Configuring UDLD
This chapter describes how to configure the UniDirectional Link Detection (UDLD) protocol on the
Cisco 7600 series routers.
For complete syntax and usage information for the commands used in this chapter, refer to the Cisco IOS
Note
Master Command List, Release 12.2SX at this URL:
http://www.cisco.com/en/US/docs/ios/mcl/122sxmcl/12_2sx_mcl_book.html
This chapter consists of these sections:
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For additional information (including configuration examples and troubleshooting information), see the
Tip
documents listed on this page:
http://www.cisco.com/en/US/products/hw/routers/ps368/tsd_products_support_series_home.html
Understanding How UDLD Works
These sections describe how UDLD works:
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UDLD Overview
The Cisco-proprietary UDLD protocol allows devices connected through fiber-optic or copper (for
example, Category 5 cabling) Ethernet cables connected to LAN ports to monitor the physical
configuration of the cables and detect when a unidirectional link exists. When a unidirectional link is
detected, UDLD shuts down the affected LAN port and alerts the user. Unidirectional links can cause a
variety of problems, including spanning tree topology loops.
OL-4266-08
Understanding How UDLD Works, page 49-1
Default UDLD Configuration, page 49-3
Configuring UDLD, page 49-3
UDLD Overview, page 49-1
UDLD Aggressive Mode, page 49-2
Cisco 7600 Series Router Cisco IOS Software Configuration Guide, Release 12.2SX
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