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New Member

What trigger Line Protocol Down?


Recently I encountered a problem on "line protocol down" as I'd posted on 4th April.

Could anyone direct me to any webpage or sites where there's a detail explaination of how & what would trigger a line protocol down. Or these kinda data-link failure. Thanks!

With regards


Re: What trigger Line Protocol Down?

Hi Friend,

There could be few reasons majorly physical layer issue when the line protocol goes down.

Can you please update which interface was showing line protocol down. Logical interface (SVI) on layer 3 switch, physical port on layer 2/3 switch or any physical interface on router?

If it is a physical interface on layer 2 switch it is majorly a physical layer issue or may be that particular vlan asscosiated to that port got deleted.

If it is a layer 3 logical interface showing line protocol down may be there is no vlan associated to that vlan configured on layer 2 switch port or no trunk carrying that vlan on that switch.

HTH, if yes please rate the post.


New Member

Re: What trigger Line Protocol Down?


thanks for the reply.

I've resolved the problem by fixing the duplex & speed for the switch port & the remote PC NIC. (Although my previous setup that work for other sites are all in auto / hardware default settings)

I would like to know of any explaination on "line protocol down", webpages or sites to elaborate what might happen to my customer.

Thank you!