Pls explain about the output for tdr value which ran on cisco switch

[13jobsp90]

I have a tested a tdr cable diagnostic with changing 2 lan cables for a pc  from the same interface itself.Below are the ouput

Interface Speed Local pair Pair length Remote pair Pair status
--------- ----- ---------- ------------------ ----------- --------------------
Gi1/0/35 1000M Pair A 64 +/- 10 meters Pair B Normal
Pair B 64 +/- 10 meters Pair A Normal
Pair C 64 +/- 10 meters Pair D Normal
Pair D 64 +/- 10 meters Pair C Normal

after changing the lan cable 

Interface Speed Local pair Pair length Remote pair Pair status
--------- ----- ---------- ------------------ ----------- --------------------
Gi1/0/35 1000M Pair A 55 +/- 10 meters Pair A Normal
Pair B 55 +/- 10 meters Pair B Normal
Pair C 55 +/- 10 meters Pair C Normal
Pair D 55 +/- 10 meters Pair D Normal

What is the difference between these 2 outputs? Switch is 2960s model with 1 g capacity

[Torbjørn]

TDR has determined that one of the cables is 9 m shorter(64m - 55m, also note the 10m margin for error) than the other and that there are no detected errors. 

If you wish to learn more about TDR I can recommend reading this KB article by @Leo Laohoo: https://community.cisco.com/t5/networking-knowledge-base/how-to-use-time-domain-reflectometer-tdr/ta-p/3119327 

[Martin L]

because of 10 meter of margin for error, there could be no significant difference between two ouptuts.

Regards, ML
**Please Rate All Helpful Responses **

[Leo Laohoo]

What is the exact IOS version? 

[vishalbhandari]

@13jobsp90  

Summary of Key Differences:

Aspect First Output Second Output

Pair Length	64 meters	55 meters
Remote Pair Mapping	Pairs are mismatched (e.g., A -> B)	Pairs are correctly mapped
Cable Wiring Quality	Possible incorrect pinouts	Properly wired

---

Implications:

1. First Cable:

   • Likely has a pair mismatch, but it still works due to auto-MDI/MDIX on the switch.
   • Slightly longer length may increase latency or attenuation, but it is within acceptable limits for gigabit Ethernet (maximum length is 100 meters).

2. Second Cable:

   • Correctly wired with shorter length, making it the better cable in terms of compliance and performance.

---

Recommendation:

• Use the second cable for better long-term reliability and adherence to Ethernet standards.
• If possible, avoid using cables with pair mismatches, as they can cause issues with certain non-Ethernet devices or in more complex network setups.

[Leo Laohoo]

@vishalbhandari 

These ChatGPT-generated answers are pretty good at filling the spaces but, in reality, does not really answer the question.  It seems to be avoiding answering the question.