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fibre uplink going up and down

hi i have a prob. i have a 2950 xl switch with fibre uplink.every 5 to 10 min time intervel the interface is going up and down.i changed the cable from, patch panel. but still the same.

our cable team tested the fibre link it is ok.

my switch is in VLAN.

int fa0/1 to 24 in vlan no 8

interface fa0/1-24

switchport access vlan8

spantree portfast

the above 3 line is for all the 24 ports.

and my uplink config is.

int fa2/4

trunking is enabled with dot1q encapsulation.and the port is in trunk mode.

i can see input errors and Crcs on my fibre link.around 300 input errors and 160 or some crcs.

once i got an error like

%sys-3 cpu HoG.

and sometimes on console its showing some messages like.

"int fa2/4 is experiencing errors".

kindly help.




Re: fibre uplink going up and down

Hi Binoy,

Can you please paste the full erro message which is coming with CPU HOG error message.

Read this link for more details on CPU HOG error message

Also can you try disabling spantree portfat for port fa0/24 as it is a trunk port and cisco does not recommend port fast on trunk ports especially.




Re: fibre uplink going up and down

Is this port an actual fiber port or you running a media converter . What is it connected to on the far end and what is the config ? This almost sounds like some sort of duplex mismatch but you don't indicate how it is connected to the other end and what equipment is on the far end .

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