Test cable-diagnostics output

[samuel.domb]

Hi.

Can some one tell me what's the meaning of the output:

Interface Speed Local pair Pair length        Remote pair Pair status

--------- ----- ---------- ------------------ ----------- --------------------

Gi0/40    100M  Pair A     2    +/- 4  meters Pair A      Normal

                Pair B     2    +/- 4  meters Pair B      Normal

                Pair C     2    +/- 4  meters Pair C      Short

                Pair D     2    +/- 4  meters Pair D      Short

From the command

test cable-diagnostics tdr int gi 0/40

It's normal?

If not, then. the problem is on the cable or on one of the interfaces?

The interface is connected between a fastethenert on a 2811 router and a 3560-48 switch.

The cable is a straight through cat 5e cable. (I have changed several cables with same result).

Thanks in advance.

Best regards.

Samuel.

[Leo Laohoo · Accepted solution]

Can some one tell me what's the meaning of the output:

I can!

Test is taken from a 3560G-48.

Cable length is between 2 to 5 metres.  The TDR test can "see" Pair A and B.  Unless you are using PoE (Pair "C") then you "shouldn't" be worried about it.

Pair "D" supports GigabitEthernet.

My personal opinion?  You've got a crappy cable.  I don't care if you don't need to use PoE or Gig interface, I will never (ever) take a cable unless all four pairs are tested Normal.

[samuel.domb]

Thanks very much for your answer.

Question:

There are any possibility by any chance that one of the physical interfaces, either on the router or the switch is damaged?,

Thanks again.

Regards

[samuel.domb]

Test cable-diagnostics output

Thanks very much for your answer.

Question:

There are any possibility by any chance that one of the physical interfaces, either on the router or the switch is damaged?,

Thanks again.

Regards

[Leo Laohoo]

There are any possibility by any chance that one of the physical interfaces, either on the router or the switch is damaged?,

There's a chance but it's very slim.  There's another way to determine this.  Un-patch the cable from the remote end and run the TDR test again, if you get the same result, i.  e.  Normal, Normal, SHORT, SHORT, then your cable is faulty.

Just because the remote end does NOT support PoE or GigabitEthernet does not mean that the last two pairs will come back with a bad result.

Another thing, just because your cable came from a fresh pack does NOT mean that all four pairs are expected to work fine.  Remember, during the manufacturing of these cable the products COULD BE tested.  When they are tested, the TDR the manufacturer will only test the FIRST TWO PAIRS.