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[Waltorres]

Good Evening, Need help understanding TDR results:

The First Test shows:

Pair A  Pair A

Pair B  Pair B

Pair C  Pair C

Pair D  Pair D

Second Test Shows:

Pair A  Pair B

Pair B  Pair A

Pair C  Pair D

Pair D  Pair C

Why is there a difference between the local pairs and remote pairs  A->A   A->B ?

Interface Speed  Local pair    Pair length      Remote pair Pair status
--------- ----- ---------- ------------------ ----------- --------------------
Te1/0/42 1000M Pair A 119 +/- 10 meters Pair A Normal
                           Pair B 122 +/- 10 meters Pair B Normal
                           Pair C 124 +/- 10 meters Pair C Normal
                           Pair D 119 +/- 10 meters Pair D Normal

Interface Speed Local pair Pair length Remote pair Pair status
--------- ----- ---------- ------------------ ----------- --------------------
Te1/0/44 5000M Pair A 96 +/- 10 meters Pair B Normal
                           Pair B 92 +/- 10 meters Pair A Normal
                           Pair C 97 +/- 10 meters Pair D Normal
                           Pair D 94 +/- 10 meters Pair C Normal

[Leo Laohoo]

What firmware is that switch running on? 

Te 1/0/42 output looks dodgy.

[Waltorres]

Cisco 9300 version 16.12

Meraki MR56 27.7.1

I'm getting CRC errors on Te1/0/42 and it keeps downshifting to 1000Mbit.

That's the reason I posted this question because of the different TDR results on the same 10GBaseTX ports

Te1/0/42 Wireless Access Po connected trunk a-full a-1000 100/1000/2.5G/5G/10GBaseTX
Te1/0/43 Wireless Access Po connected trunk a-full a-5000 100/1000/2.5G/5G/10GBaseTX
Te1/0/44 Wireless Access Po connected trunk a-full a-5000 100/1000/2.5G/5G/10GBaseTX

[Leo Laohoo]

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@Waltorres wrote:

Cisco 9300 version 16.12

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Not helpful. 

The last number is crucial.  

[Waltorres]

16.12.02

[jmcdonnell3]

In direct response to your question:  You may be using a straight-through cable for one & the other may be a crossover cable.

Either way, you're exceeding 100 meters for the Gigabit cable & some links greater than Gigabit (like your 5Gb) have a maximum length of only 30 meters so I wouldn't trust that design.

[Leo Laohoo]

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@jmcdonnell3 wrote:

Either way, you're exceeding 100 meters for the Gigabit cable & some links greater than Gigabit (like your 5Gb) have a maximum length of only 30 meters so I wouldn't trust that design.

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Not so fast.  
There is a reason why I am asking for the exact firmware.  

[Waltorres]

GM, the firmware is 16.12.02 and most of our runs use Cat5e cables (90%)

[Leo Laohoo]

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@Waltorres wrote:

GM, the firmware is 16.12.02 and most of our runs use Cat5e cables (90%)

---

Based on my experience, I do not trust any TDR output from 16.12.1 up to 16.12.2.  

If there is a need to use 16.12.X, 16.12.3a is a good and stable OS.  < --- Read between the lines.

[Martin L · Accepted solution]

A->B  < i think it is crossover cable while A->A or B >B are regular straight thru.

your distance or length is in  meters; you should not have anything longer then 100 meters when using CAT5/6 cables.

Regards, ML
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