Looop back not set (sorry to ask very basic quiestion)

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Oct 8th, 2008
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sorry to ask this basic quistion can some one tell what does this xcatly mean by Loop back Not Set .. ..(out put of show interface)

thx in advnce


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Tim Smith Wed, 10/08/2008 - 05:15
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You can set your interface into a loop back mode to test it.

Loopback not set is normal to say that you do not have this enabled.



bagvanliju Wed, 10/08/2008 - 05:20
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thanks for he reply tim.was checking onelink which was having errors ...Telco has provided loop towards customer ...cusotmer was not able to see the loop .......as per u loop back is enabled by default in all interface ..???

bagvanliju Wed, 10/08/2008 - 05:22
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hai raj,

thanks for the responce ..little confusion still ...and not clear ...u mean to say loopback not set and loop back interface are same ??!!!!

Tim Smith Wed, 10/08/2008 - 05:33
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Raj was talking about a loopback interface.

You can create these virtual interfaces, and use them for management, routing, voice etc. They are a different thing.

You are talking about the loopback setting on a serial interface. What type of interface is it?

If the telco sets a loopback on their equipment then you should see your interface as down, because it will effectively cut you off before your interface. The telco can then do tests down the line, this verifies the line all the way to the end of their equipment usually.

You will not see loopback set in this case.

You would see loopback set, if you were trying to do a loopback from your side.

What errors are you seeing? What type of interface is it?



bagvanliju Wed, 10/08/2008 - 05:43
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Hai Tim,

This is an internet link.Serial interface...(encap HDLC)....(as per telco when they are givn loop from their demar pointtowards ISP router ...they were able to see the loop and able to ping the self ip ..confirmed no prob till demarc ...but givn the same loop towards customer he is not gettng ....confirmed that customer end CSU/DSU is working ....)

so got little confused with this line ..."loop back not set" ...


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