naftoli@aecom.YU.EDU (Robert N. Berlinger) (01/24/88)
We are going to be installing a fiber optic backbone, initially
running Ethernet, but we want to migrate to FDDI as the standard
is cured.
Does a choice of multi-mode or single-mode fiber make a difference
as far as FDDI? In not, which is best for a lan (i.e., which
will be the most popular, easy to buy hardware for, etc.)? From
what I read, most phone companies use mainly single mode for
trunk lines (T4 and all that...).
I understand that single-mode fiber requires a laser light source
(although this may be changing), but multi-mode only requires the
cheaper LED light source.
A clarification will be most appreciated.
--
Robert N. Berlinger naftoli@aecom.yu.edu
Supervisor of Systems Support
Albert Einstein College of Medicine Compuserve: 73047,741
UUCP: ...{philabs,cucard,pegasus,rocky2}!aecom!naftoli GEnie: R.Berlingerkwe@bu-cs.BU.EDU (kwe@bu-it.bu.edu (Kent W. England)) (01/26/88)
In article <1573@aecom.YU.EDU> naftoli@aecom.YU.EDU (Robert N. Berlinger) writes: >Does a choice of multi-mode or single-mode fiber make a difference >as far as FDDI? I think the emerging FDDI spec allows for several options in selection of fiber type. > In not, which is best for a lan (i.e., which >will be the most popular, easy to buy hardware for, etc.)? I think single mode fiber is impractical for LANs. Connectorizing single mode fiber requires a portable lab in a truck. Multimode fiber connectorizing and splicing can now be done out of a kit by a meticulous technician, such as a broadband tech. Single mode requires a laser, multimode can use LEDs. The FDDI ring will be limited to 23 km or less. This is very practical for multimode and large campuses. Single mode not required. AT&T seems to be dominating the multimode arena. They go with 62.5 micron fiber. I would recommend that diameter. Then your fiber could also be used for telephone multiplexers. A big design decision is star vs ring. FDDI is logical ring, but you can install it physically as a star or ring. Design for expansion and know the FDDI limits, which I think are 23 km. [Correct me, but don't flame me, please.] I haven't yet decided whether to stay with AT&T standard SMA connectors or use ST connectors. The screw on SMAs are very difficult to patch and repatch. Perhaps the mini bayonet STs are better. Comment? Boston University has installed a 62.5 u physical ring running Pronet 80. We connectorize and maintain the network ourselves. -- ------------------------------------------------------------------- Kent W. England | Boston University Network & Systems Engineering Group | Information Technology kwe@bu-it.bu.edu internet | 111 Cummington Street itkwe@bostonu BITnet | Boston, MA 02215 harvard!bu-cs!kwe UUCP | (617) 353-2780 -------------------------------------------------------------------
ron@topaz.rutgers.edu (Ron Natalie) (01/28/88)
The ST connectors are the new AT&T ones. The SMA's are what nearly every piece of fiber equipment currently uses. Of course, the old AT&T biconical connectors while theoretically a lot better, were pretty annoying because NOBODY sold them other than AT&T (and even AT&T sometimes denied knowledge of them). -Ron