amc@cup.portal.com (Alan Michael Crawley) (04/07/91)
Alot of people are talking about the costs of 10baseT vs. cheapnet. My company engineers and INSTALLS large (50-1500 user) 10baseT nets and cable plants. Also FDDI. 10baseT is only cheaper when the net is over 100 users big. Savings is in administration costs.(adds moves and changes) and existing wire savings. Little departmental nets don't benefit that way. Large nets also benefit from existing phone wire. We do cable plant audits to test existing wire for 10baseT. Almost 100% is suitable for ethernet if we change out the 66 blocks for 110 or Krone...plus a few other secrets. Alan Crawley VP Engineering APEX COMMUNICATIONS - MOUNTAIN VIEW CALIFORNIA - 415-967-9200
henry@zoo.toronto.edu (Henry Spencer) (04/07/91)
In article <40993@cup.portal.com> amc@cup.portal.com (Alan Michael Crawley) writes: >10baseT is only cheaper when the net is over 100 users big. Savings is in >administration costs.(adds moves and changes) and existing wire savings. Administration costs depend heavily on circumstances. If you've got an abundance of unsophisticated users who will happily unplug things at random times, bus-based technologies like thinwire are a serious mistake, and 10baseT is just what the doctor ordered, even for a small net. -- "The stories one hears about putting up | Henry Spencer @ U of Toronto Zoology SunOS 4.1.1 are all true." -D. Harrison| henry@zoo.toronto.edu utzoo!henry
paul@hpsciz.sc.hp.com (Paul Mooney) (04/09/91)
Interesting ... One really must define "administrative costs." The major disadvantage of coax is the bus topology. At HP, where the user community cannot function when the LAN is down, StarLAN makes sense even if the initial installation costs are higher. Paul Mooney Network Services Hewlett Packard
pat@hprnd.rose.hp.com (Pat Thaler) (04/12/91)
In comp.dcom.lans, jbreeden@netcom.COM (John Breeden) writes:
RJ45s are used because the original concept of 10baseT was to use the exist-
ing TELEPHONE wiring - and there's been a TELEPHONE wiring standard in use
for years now .... AT&T's PDS (Premise Distribution System).
I award John Breeden the prize for the most accurate explanation of why
10BASE-T used the 8-pin jack (at least of those replies that reached
my system by today). The use of the 8 pin jack in PDS and other office
wiring systems was a major factor in the decision. It was also in use
in the 1BASE5 (StarLAN) standard and in ISDN (which specifies pinouts
for both 6 and 8 pin).
On other points: Link Integrity Test is a mandatory part of the 10BASE-T
standard and does not require additional wires. SQE Test occurs between
the MAU and its local DTE and does not involve the twisted pair
wire.
Some vendors of 10BASE-T cards provide a connector on the card with the
pairs from pins 4 & 5 and 7 & 8 wired to it so that a phone may be
attached to the card without a separate splitter. In other words, some
cards provide a built-in splitter.
Pat ThalerPLS@cup.portal.com (Paul L Schauble) (04/14/91)
I think I missed the beginning of this discussion....
When you say 10BaseT is cheaper, what are you comparing it to?
++PLSdjdove@hprnd.rose.hp.com (Dan Dove) (04/16/91)
Regarding this quote " At HP, where the user community cannot function
when the LAN is down, StarLAN makes sense even if the initial installation
costs are higher". from
Paul Mooney
Actually, we can function, however, our performance is significantly reduced.
Also, we now refer to 10-BASE-T networking as "EtherTwist" rather than StarLAN.
Finally, his point is correct regarding the cost of "down-time" being much greater
than the initial cost of installation. Don't forget that installation cost differential
between coax & UTP is reduced if you can take advantage of existing wiring.
Dan Dove
Roseville Networks Division
Hewlett Packardandrew@jhereg.osa.com (Andrew C. Esh) (04/16/91)
In article <41255@cup.portal.com> PLS@cup.portal.com (Paul L Schauble) writes: >I think I missed the beginning of this discussion.... > >When you say 10BaseT is cheaper, what are you comparing it to? > > ++PLS To this point, the main contender has been ThinNet (RG58 Coax), since it does not require a Hub. I think 10baseT is better because it is physically more reliable, and easier to connectorize and maintain. The wire is cheaper, too. Hey folks, I've noticed hubs are getting down in the $50/port range. Where does that put us with this discussion? Are you ThinNet types gonna go away and cry in your cornflakes yet? :-) (Just kidding, I like ThinNet too.) -- Andrew C. Esh andrew@osa.com Open Systems Architects, Inc. Mpls, MN 55416-1528 Punch down, turn around, do a little crimpin' (612) 525-0000 Punch down, turn around, plug it in and go ...
djdove@hprnd.rose.hp.com (Dan Dove) (04/25/91)
In comp.dcom.lans, andrew@jhereg.osa.com (Andrew C. Esh) writes: > Test equipment? Yes. Use a pair tester. Use a cable scanner. That's about > all I can say about that. If you wish to ** Certify ** your wiring to comply with 10-BASE-T specifications for attenuation, near-end crosstalk, continuity, and burst noise, HP makes a product (HP28687A) which performs this function. Contact the local Test & Measurement sales person. It works on 50 pin TELCO connections as well as RJ45, and does up to 12 10-BASE-T nodes at a time. Dan Dove Roseville Networks Division, HP