I have 3560 with 12.2.37 se1 connnected via
fiber to 3550 with 12.1.22.ea4
I am enabling udld aggressive
as soon as i enable this my fiber ports go into error disble
before I enable this everything looks good on the interface no errors
Anybody seen this issue
You need to configure udld in aggressive mode on the other switch as well. In udld aggressive mode, the switch expects to receive a "valid reply message" ( sort of hello) from the other switch within a specific period of time. If this does not happen, the port id "disabled"
Hope this helps
It appears that 3560 is not receiving the "valid reply" from 3550 and that is the reason it's port is being "disabled".
Are the fiber strands OK? properly connected?
what udld aggressive mode does is, it will make eight attempts to re-establish the UDLD neighbor relation before error disabling the port if the 3560 is not receiving any responses from the 3550.
The last time this happened to me was a faulty sfp on my 3560.
Couple of things to check
Try replacing your fiber cable if that does not help try another port.
Also you might what to disable udld and enable udld debug event / packet before enabling udld again to see what the problem might be.
this is from debug
%UDLD-4-UDLD_PORT_DISABLED: UDLD disabled interface Gi0/2, unidirectional link detected
%PM-4-ERR_DISABLE: udld error detected on Gi0/2, putting Gi0/2 in err-disable state
%udld_linkchange called, reason = link, new_link_state = down, cookies = 1
%LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/2, changed state to down
%LINK-3-UPDOWN: Interface GigabitEthernet0/2, changed state to down