Udld Software And Hardware Requirements - Cisco WS-C4003 - Catalyst 4000 Chassis Switch Software Configuration Manual

UDLD Software and Hardware Requirements

The switch periodically transmits UDLD messages (packets) to neighbor devices on ports with UDLD
enabled. If the messages are echoed back to the sender within a specific time frame and they are lacking
a specific acknowledgment (echo), the link is flagged as unidirectional and the port is shut down.
Devices on both ends of the link must support UDLD in order for the protocol to successfully identify
and disable unidirectional links.
With supervisor engine software release 5.4(3) and later, you can specify the message interval between
Note
UDLD messages. Previously, the message interval was fixed at 60 seconds. With a configurable message
interval, UDLD reacts much faster to link failures.
Figure 22-1
from Switch A on the port. However, Switch A does not receive traffic from Switch B on the same port.
UDLD detects the problem and disables the port.
Figure 22-1 Unidirectional Link
TX
TX
UDLD Software and Hardware Requirements
UDLD requires the following hardware and software:
•
•
Software Configuration Guide—Catalyst 4000 Family, Catalyst 2948G, Catalyst 2980G, Releases 6.3 and 6.4
22-2
shows an example of a unidirectional link condition. Switch B successfully receives traffic
Switch A
RX
RX
Switch B
For fiber-optic links:
Supervisor engine software release 5.1 or later releases
–
– Ethernet, Fast Ethernet, or Gigabit Ethernet fiber-optic switching modules
For copper links:
– Supervisor engine software release 5.2 or later releases
Ethernet or Fast Ethernet copper switching modules
–
Chapter 22 Configuring UDLD
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