cat5 cable maximum rated speed?

[vital]

in this book i'm reading it says that the maximum rated speed of cat5 cable is 100Mbps. How can this be possible if 1000BaseT uses cat5?

 

[ScottMac]

First, check the unit of measure (100MHz versus 100 Mbps, perhaps?).

Next, check the release date of the book, original date of publishing, revisions, updates, etc.

Finally, there *is* a context to that statement. For example, if you were to use a broadband balun (commonly available for structured cabling), you could feed cable TV on that UTP / Cat{anything} over the rated 100 meter span successfully. That would be significant, since the upper UHF channels are above 900MHz.

Other factors are power levels, type of signaling / encoding, and the receiver's sensitivity and selectivity.

General statements in print that assign absolutes are usually done to keep things simple. It is extremely rare to be without exception and nuance.

Within the scope of the thing where you read that, it's "true enough" or maybe "the current version of the truth." If you talk to an RCDD certified person, they can explain and demonstrate to you why it's "not necessarily" the truth.

Scope and context are everything for this kind of discussion.

Good Luck

Scott

 

[spidey07]

Because that's the officially rated and tested speed of category 5. All tests for category 5 certification are based on 100 Megabits, 125 MHz baud.

 

[vital]

Originally posted by: spidey07
Because that's the officially rated and tested speed of category 5. All tests for category 5 certification are based on 100 Megabits, 125 MHz baud.

So a Gigabit Ethernet network that uses cat5 cable can only transfer speeds up to 100Mbps?

 

[spidey07]

Originally posted by: vital

Originally posted by: spidey07
Because that's the officially rated and tested speed of category 5. All tests for category 5 certification are based on 100 Megabits, 125 MHz baud.

So a Gigabit Ethernet network that uses cat5 cable can only transfer speeds up to 100Mbps?

No. I only stated category 5 specifications and what is needed to meet category 5 specs.

Cat5 existed well before 1000 Base-T. The good news is 1000 Base-T took this into account.

This is one of the big misconceptions with cabling - "Well it will just negotiate speed". NO! It does not! Each interface sends capabilities on what it can do speed/duplex wise and the max is chosen. Google 1000 Base-T autonegotiation to learn more.