if using on optic fiber port,
should it apply on root port or designated port ? access switch only or both distribution layer and access switch or core + distribution layer or access switch?
where should it apply?
If used on fibre optic port, configure both ends with UDLD.
If one end does not support UDLD then don't configure it on the other end.
i find that UDLD is not enabled in etherchannel in real practice of an ISP company.
not easy to find a scenario to apply CCNP knowledge in real practice
it seems most security commands only works when using one cable uplink to core switch for small bandwidth
i guess only access switch can be applied