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Merge pull request #304 from fjcapdevila/patch-13

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Improve EMI section.
This commit is contained in:
Mike Fiedler
2016-04-07 12:10:24 -04:00
parent fb96bca3a5 9d3f44fa16
commit 732b9f4a5a
1 changed files with 8 additions and 8 deletions
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16
networking_201.rst
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@@ -201,7 +201,7 @@ Most layer problems are usually traced back to one of the following causes:
* Bad cabling
* Mismatched duplex/speed
* Electrical interference (EMI)
* Electromagnetic interference (EMI)
* Network congestion
To find the metrics below, use either `ip -s link`, or `ethtool -S`.
@@ -376,13 +376,13 @@ cause of duplex/speed mismatch.
Some devices don't play nicely with each other when auto-negotiation is
enabled on both sides, so be sure to verify what auto-negotiation resulted in.
Electrical interference
-----------------------
Electromagnetic interference (EMI)
----------------------------------
The symptoms of electrical interference can be seen by an increase of CRC errors.
Electrical interference can be caused by any number of things: power cables nearby,
The symptoms of electromagnetic interference can be seen by an increase of CRC errors.
Electromagnetic interference can be caused by any number of things: power cables nearby,
mechanical systems (such as HVAC units), etc.
Since a visual inspection will often reveal electrical interferance culprits easier
Since a visual inspection will often reveal electromagnetic interference culprits easier
than checking metrics, it's simpler to do a visual inspection first if you suspect
this.
The problem can sometimes be solved/alleviated by replacing the cable with STP
@@ -401,9 +401,9 @@ A link tester, however, is different from a cable certifier, which will verify
full compliance with TIA/EIA and ISO cable standards, including metrics for
crosstalk allowance, cable length, current loss, and many others.
If you need to test cable used in low-impact environments (eg, wall jack to
If you need to test cable used in low-impact environments (e.g., wall jack to
desktop), a link tester is usually sufficient.
If you need to test cable used in high-impact environments (eg, datacenter),
If you need to test cable used in high-impact environments (e.g., datacenter),
opt for a cable certifier.
Reputable cable vendors will have already run certification tests on cable,
so this is only useful if you are routinely making your own cable (which