Re[2]: Ethernet Compliance
Vic Boersma had the following to say about Ethernet cabling (my comments have been added in parentheses. Ron Fotino __ Reply Separator _ Subject: Re: Ethernet Compliance Author: Victor L. Boersma 102126@compuserve.com at !INTERNET List-Post: emc-pstc@listserv.ieee.org Date:5/28/96 10:33 PM You're asking an unaswerable question, in my opinion. (1) Many buildings are prewired and can't handle any more wire, you've got to make do with what is there, or make rewiring part of the contract. You're not likely going to be the lowest bidder on the job, if you do. (However, if this is true, the premise wiring is likely to be Cat. 3 which won't support 100Base-T. That means re-wiring becomes a necessity. Premise wiring with available drops is the absolute best way to go; if it hasn't been done yet and is part of the job, Cat. 5 is quite useful and not extremely expensive.) (2) If the people who do the wiring know what they are doing, you can have very good results using either coax or CAT 5. If the people doing the wiring don't know what they are doing, they are likely going to make a mess out of either. Believe me, I have seen people making a horrible mess out of either. (3) You have not mentionned running fiber (Fiber is extremely expensive compared to UTP.) (4) You have not mentionned doing a wireless distribution (Wireless is also very expensive, limited in coverage area, and not usable in every country/region.) I suggest you take a building distribution specialist group on to discuss this further. I have included a number of my friends of that persuasion in the distribution. Regards, Vic Boersma
Re: Ethernet Compliance
Hi Glen, Let me try to answer your inquiries from the perspective of a networking manufacturer. When we do our EMI testing, we use the cable that would normally be used with the product. That means that if the product is meant to be used with Cat. 5 Unshielded Twisted Pair (UTP) cabling, it is tested with UTP. We presently have available 100Base-T products that MEET the class A requirements using Cat. 5 UTP. Incidentally, most if not all of the networking manufacturers use shielded ports that are tied in to ground somehow within the product, even if the specified cabling is UTP. The reason for this is that noise radiated within the box will couple onto the UTP if it is not shielded at the connector. The cable shielding is not necessary if the design is done properly. If you have more questions, please let me know. Sincerely, Ron Fotino Principal Compliance Engineer Cabletron Systems, Inc. __ Reply Separator _ Subject: Ethernet Compliance Author: Gassaway Glen p25...@gegpo8.geg.mot.com at !INTERNET List-Post: emc-pstc@listserv.ieee.org Date:5/28/96 2:41 PM We have a decision to make on one of our systems regarding 10 base T LAN cabling. It is intended to carry 10BaseT (10Mb/s) traffic, but we want to install it with the capability to upgrade to 100BaseT (100 Mb/s). The question is whether or not to use shielded cabling. We know that the industry standard in the US and in most of the world is to use unshielded twisted pair cabling (like cat 5). Because of this, most hubs, routers, etc. have unshielded, ungrounded connectors on them. We can buy shielded twisted pair cables and connectors, but obviously the shield will not be grounded when simply plugged into an ungrounded jack. The question is whether or not unshielded 10 base T or 100 base T will meet FCC\CISPR Radiated limits. The limits applicable to our product are class A FCC. Could anyone on the net offer some guidance about this issue? Thanks in advance Glen Gassaway Motorola GSTG EMAIL: p25...@email.mot.com
Re: Ethernet Compliance
You're asking an unaswerable question, in my opinion. (1) Many buildings are prewired and can't handle any more wire, you've got to make do with what is there, or make rewiring part of the contract. You're not likely going to be the lowest bidder on the job, if you do. (2) If the people who do the wiring know what they are doing, you can have very good results using either coax or CAT 5. If the people doing the wiring don't know what they are doing, they are likely going to make a mess out of either. Believe me, I have seen people making a horrible mess out of either. (3) You have not mentionned running fiber (4) You have not mentionned doing a wireless distribution I suggest you take a building distribution specialist group on to discuss this further. I have included a number of my friends of that persuasion in the distribution. Regards, Vic Boersma
RE: Ethernet Compliance
Intel sells a 100bT card for use with Class 5 UTP cable that is FCC Class B Certified. I'm sure there are other competitive brands out there that are also Class B. Apparently, it's possible to pass. Regards, tony_fredriks...@netpower.com -- From: p25800 To: EMC-PSTC Subject: Ethernet Compliance List-Post: emc-pstc@listserv.ieee.org Date: Tuesday, May 28, 1996 2:41PM We have a decision to make on one of our systems regarding 10 base T LAN cabling. It is intended to carry 10BaseT (10Mb/s) traffic, but we want to install it with the capability to upgrade to 100BaseT (100 Mb/s). The question is whether or not to use shielded cabling. We know that the industry standard in the US and in most of the world is to use unshielded twisted pair cabling (like cat 5). Because of this, most hubs, routers, etc. have unshielded, ungrounded connectors on them. We can buy shielded twisted pair cables and connectors, but obviously the shield will not be grounded when simply plugged into an ungrounded jack. The question is whether or not unshielded 10 base T or 100 base T will meet FCC\CISPR Radiated limits. The limits applicable to our product are class A FCC. Could anyone on the net offer some guidance about this issue? Thanks in advance Glen Gassaway Motorola GSTG EMAIL: p25...@email.mot.com
