Ken, I'm actually responding here to a PM from another poster, and in the process you have provided me with a good segue into what I wanted to discuss. I know that you know this stuff, but I thought it would be good to put on the board for others.
If I could suggest, let's put Tut and other plays in the DSL space aside for the moment and discuss some generics here.
DSL was originally designed around the longitudinal parameters associated with outside plant (OSP) non-loaded twisted pairs. Reference to Cat 5 cable is often confused with this, when making reference to high quality OSP.
Cat 5, by definition, is an in-building LAN cabling specification with specific transmission- and environmental-related performance stipulations and distance constraints (limited to 90 meters on the floor, and 10 meters in closets and under desks). It was brought about my many years of grief and tears in the commercial building cabling space.
This taxonomy of in building cabling, where different grades of 4-pair cables are rated as Cat 3, 4 and 5, was defined by the Telecommunications Industry Association and ANSI in the ANSI/EIA/TIA/ 568 Standard
Their 570 standard defines the smaller commercial and residential models. Standard 569 defines pathways and spaces in commercial structures, and is primariliy an aid to architects and facilities managers in prepping base building and work areas for the laying of cables. These and other standards are listed below.
From: cableu.net
--begin snip
EIA/TIA 568A Commercial Building Telecommunications Wiring Standard
EIA/TIA 569A Telecommunications Wiring Pathways and Spaces
EIA/TIA 570 Light Commercial and Residential Telecommunications Cabling
EIA/TIA 606 Telecommunications Cabling System Administration
EIA/TIA 607 Telecommunications System Grounding and Bonding Requirements
Several technical service bulletins (TSBs) have also been published
relating to this standard, to clarify various points in the standard:
TSB-36 UTP Categories 3, 4, and 5 Defined
TSB 40A UTP Connecting hardware for Category 3, 4, 5
TSB-53 Additional specifications for STP (shielded twisted pair) hardware
TSB-67 Transmission performance specification for field testing UTP
TIA/TSB-72: Centralized Optical Fiber Cabling Guidelines
TSB-75 Defines "zone distribution systems" for horizontal wiring
-----end snip
As to who "owns" Ethernet, I don't know this to be pertinent anymore, maybe it still is, but at one time all 802.3 MAC Layer addresses for Ethernet were administered and parceled out by DEC, Zerox and IBM. They each maintained IEEE allocations of addresses in a custodial manner, and were designated by the IEEE (I think?), since Ethernet is an IEEE standard primarily, to dole them out to other manufacturers to burn into their NIC cards, as required. I am not privy to the deal making end of this, however.
And the data link attributes of Ethernet, which are in fact situated at Layer 2, converge with physical media ~half way down Layer One of the OSI RM, as Peter indicated. However, since Ethernet Layer 2 data link control attributes do exist, I would have to differ with Peter on this one, a bit, but I'll give him the benefit of simply omitting it in his focus on the lower vs higher layer uses of Ethernet, and simply didn't include L2 in the post.
But there are no layer 3 and 4 processes taking place in Ethernet.
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As for hotel rooms, Cat 5 twisted pair has now begun to displace coax in the video space, read: TV and entertainment links in hotels, hospital bedsides, in-homes. Many new installations borrow from bal/un technologies such as those which were pioneered by T back in the late Eighties/early Nineties, and later perfected by a British company called CCC, a while back. Now there are a number of such video/tp companies out there, and they are beginning to penetrate, broadly.
In one example here, we are talking about two paths, which could be defined either or both, physically or logically, depending on a number of application and environmental variables. Let's consider two separate physical Cat x cabling paths, where x equals the recommended grade by the manufacturer.
Often, Cat 5 will be used, anyway, but in ways which violate 1oo meter distance rules in the risers. But that's okay because the video baluns do not abide by those constraints the way NIC manufacturers do.
One path would be used for sending actual video content over a plain old balun (an impedance matching device between coax and tp) from a controller in the control room to the guest's or patient's room where another balun exists prior to plugging into the TV, and a second cable (or arguably a second pair in the same cable, since there are four pairs per Cat x cables) for session control and other LAN-related purposes. In business, this often means support of collaborative applications and side chat, as well.
Some variants of this employ a single pair and resort to subcarrier techniques instead, for the TCP/IP over Ethernet parts. |
