Regarding cat5 vs. cat5e, I think it may be because the spec is guaranteed to 100m. Who here has tested this? I think short runs, 3m patch cables, is why I see reported Gbit speeds on cat3.
Some of the reporting here seems contradictory, but I am not a standards expert. Negotiating the highest common denominator is what I would expect. I only really care about what's happening at the port.
- Gigabit requires Cat 5 cable, but requires 4 pairs.
AFAIK Cat 5E actually. I had to redo a lot of wiring to replace plain CAT5 because it didn't work for 1Gbit.
- Gigabit requires Cat 5 cable, but requires 4 pairs.
AFAIK Cat 5E actually. I had to redo a lot of wiring to replace plain CAT5 because it didn't work for 1Gbit.
Really? I've haven't looked a that extensively but I have never seen a cat5 cable fail at a gigabit speeds. The initial version of 1000Base-T specifically called for cat5 but with slightly modified specs -- I think only for NEXT which was not specified in the cat5 standard but which most existing cat5 cables supported. Cat5e was then published and cat5 withdrawn and the ethernet spec modified to call for cat5e.
- Gigabit requires Cat 5 cable, but requires 4 pairs.
AFAIK Cat 5E actually. I had to redo a lot of wiring to replace plain CAT5 because it didn't work for 1Gbit.Nope. It’s a common misconception that gigabit requires Cat 5e. It does not.
Nope. It’s a common misconception that gigabit requires Cat 5e. It does not.
- Gigabit requires Cat 5 cable, but requires 4 pairs.
AFAIK Cat 5E actually. I had to redo a lot of wiring to replace plain CAT5 because it didn't work for 1Gbit.Nope. It’s a common misconception that gigabit requires Cat 5e. It does not.
Well, I have seen CAT5 cables fail at 1Gbit where CAT5E worked. The failing cables where only a few meters long. So explain that to me...
Nope. It’s a common misconception that gigabit requires Cat 5e. It does not.
The only IEEE 802.3 PMA supporting Cat3 that would be relevant is 10base-T. Clause 14.5.1 of 802.3-2018 (in the 10base-T MDI section) says:
Wasn't there some change in the specs some years ago?
I always heard that CAT 5e was essentially "backported" into CAT 5, making CAT 5e obsolete.
Nope. It’s a common misconception that gigabit requires Cat 5e. It does not.It's not a misconception. CAT5 cable is not up to spec for gigabit ethernet. It should work for shorter runs or even may be as good as 5e spec but nothing is guaranteed.
Nope. It’s a common misconception that gigabit requires Cat 5e. It does not.
When 1000base-T was specified, Cat5e didn't exist. So the standard references plain Cat5, but stipulates additional requirements that were not part of the Cat5 standard. These requirements were ultimately rolled into Cat5e. So while 1000base-T spec doesn't call out Cat5e, it does require cable that is more stringently specified than Cat5, and Cat5e meets those requirements.
The new requirements were regarding return loss and several forms of crosstalk. I find it somewhat hard to believe that people had actual problems with Cat5 patch cables because they were not Cat5e, since most would be compliant anyway, and you can't really get them anymore even if you wanted to, but the specs don't offer any guarantees (without the specified RL/crosstalk parameters of the cable), I suppose. IME problems with cabling are practically always due to poor termination or damaged cable.
- Gigabit requires Cat 5 cable, but requires 4 pairs.
AFAIK Cat 5E actually. I had to redo a lot of wiring to replace plain CAT5 because it didn't work for 1Gbit.Nope. It’s a common misconception that gigabit requires Cat 5e. It does not.
Well, I have seen CAT5 cables fail at 1Gbit where CAT5E worked. The failing cables where only a few meters long. So explain that to me...
Wasn't there some change in the specs some years ago?
I always heard that CAT 5e was essentially "backported" into CAT 5, making CAT 5e obsolete.
Well, I have seen CAT5 cables fail at 1Gbit where CAT5E worked. The failing cables where only a few meters long. So explain that to me...
- Gigabit requires Cat 5 cable, but requires 4 pairs.
AFAIK Cat 5E actually. I had to redo a lot of wiring to replace plain CAT5 because it didn't work for 1Gbit.
Really? I've haven't looked a that extensively but I have never seen a cat5 cable fail at a gigabit speeds. The initial version of 1000Base-T specifically called for cat5 but with slightly modified specs -- I think only for NEXT which was not specified in the cat5 standard but which most existing cat5 cables supported. Cat5e was then published and cat5 withdrawn and the ethernet spec modified to call for cat5e.Every resource I’ve checked still says Cat 5, not 5e, as the minimum for gigabit.
It is a misconception: as ve7xen said, the Cat 5e standard didn’t even exist when gigabit was created!
We see these problems a lot more with HDMI, whose higher bandwidth requirements (and fairly low tolerance for bit loss, thanks to encryption) spotlight the cable problems. Ethernet is just better at masking bad cables…