Quick Reference Guide

PowerConnect B-Series TI24X Configuration Guide 247
53-1002269-02
UDLD overview
9
Changing the Keepalive retries
By default, a port waits one second to receive a health-check reply packet from the port at the
other end of the link. If the port does not receive a reply, the port tries four more times by sending
up to four more health-check packets. If the port still does not receive a reply after the maximum
number of retries, the port goes down.
You can change the maximum number of keepalive attempts to a value from 3 – 64. To change the
maximum number of attempts, enter a command such as the following.
PowerConnect(config)#link-keepalive retries 4
Syntax: [no] link-keepalive retries <num>
The <num> parameter specifies the maximum number of times the port will try the health check.
You can specify a value from 3 – 64. The default is 7.
UDLD for tagged ports
The default implementation of UDLD sends the packets untagged, even across tagged ports. If the
untagged UDLD packet is received by a third-party switch, that switch may reject the packet. As a
result, UDLD may be limited only to devices, since UDLD may not function on third-party switches.
You can configure ports to send out UDLD control packets that are tagged with a specific VLAN ID
as tagged UDLD control packets. This feature also enables third party switches to receive the
control packets that are tagged with the specified VLAN.
To enable ports to receive and send UDLD control packets tagged with a specific VLAN ID, enter
commands such as the following.
PowerConnect(config)#link-keepalive ethernet 18 vlan 22
This command enables UDLD on port 18 and allows UDLD control packet tagged with VLAN 22 to
be received and sent on port 18.
Syntax: [no] link-keepalive ethernet <portnum> [vlan <vlan-ID>]
Enter the ID of the VLAN that the UDLD control packets can contain to be received and sent on the
port. If a VLAN ID is not specified, then UDLD control packets are sent out of the port as untagged
packets.
NOTE
You must configure the same VLANs that will be used for UDLD on all devices across the network;
otherwise, the UDLD link cannot be maintained.
Displaying UDLD information
This section describes the commands used to display information about a UDLD configuration.
Displaying information for all ports
To display UDLD information for all ports, enter the following command.