Usage Guidelines
By default, SNMP link traps are sent when an interface goes up or down. For interfaces such as ISDN interfaces, expected to go up and down during normal usage, the output generated by these traps may not be useful. The no form of this command disables these traps.
The permit and duplicates keywords are used together and cannot be used individually. Use the permit duplicates keyword pair when an interface is not generating SNMP linkup traps, linkdown traps, or both. When the snmp trap link-status permit duplicates command is configured, more than one trap may be sent for the same linkup or linkdown transition.
The permit duplicates keyword pair does not guarantee that SNMP link traps will be generated nor should configuring these keywords be required to receive traps.
By default, in service instance configuration mode, SNMP link traps are not sent. Also, the permit duplicates keyword pair is not available in service instance configuration mode.
The snmp trap link-status command must be used in conjunction with the snmp-server enable traps atm subif command in order to enable SNMP trap notifications on ATM subinterfaces. The snmp-server enable traps atm subif command must be configured in global configuration mode, and then the snmp trap link-status command must be configured on each ATM subinterface for which you want to enable SNMP trap notifications.
Cisco 10000 Series Router
In Cisco IOS Release 12.2(33)SB, the virtual-template snmp command has a new default configuration. Instead of being enabled by default, no virtual-template snmp is the default configuration. This setting enhances scaling and prevents large numbers of entries in the MIB ifTable, thereby avoiding CPU Hog messages as SNMP uses the interfaces MIB and other related MIBs.
If you configure the no virtual-template snmp command, the device no longer accepts the snmp trap link-status command under a virtual-template interface. Instead, the device displays a configuration error message such as the following:
Device(config)# interface virtual-template 1
Device(config-if)# snmp trap link-status
%Unable set link-status enable/disable for interface
If your configuration already has the snmp trap link-status command configured under a virtual-template interface and you upgrade to Cisco IOS Release 12.2(33)SB, the configuration error occurs when the device reloads even though the virtual template interface is already registered in the interfaces MIB.
Examples
The following example shows how to disable SNMP link traps related to the ISDN BRI interface 0:
Device(config)# interface bri 0
Device(config-if)# no snmp trap link-status
The following example shows how to enable SNMP link traps for service instance 50 on Ethernet interface 0/1:
Device(config)# interface ethernet 0/1
Device(config-if)# service instance 50 ethernet
Device(config-if-srv)# snmp trap link-status
Device(config-if-srv)# end