ciriello@lafcol.UUCP (Patrick Ciriello II) (06/20/89)
Greetings: We at Lafayette are entering into a strategic planning stage for our WAN. One of the issues that we need to resolve is what kind of wiring to put inside the buildings. If anyone has any information concerning any of the following items, please let me know (i think you might as well post them here ... others may want to know as well) o Using Token Ring over Twisted Pair (IBM, Proteon, U-B, etc) o Bridging Token Rings to 802.3 LANs o TCP/IP in a Token Ring environment o Bridging VAXen to Fiber Optic Token Ring (IBM or Proteon) o Use of shielded vs. unshielded cable o Use of fiber to the faceplate (single mode or multi mode) I am mostly interested in actual experiences, although any information would be appreciated. Thanks Patrick Ciriello II Supervisor of Networking Lafayette College
ron@ron.rutgers.edu (Ron Natalie) (06/20/89)
o Using Token Ring over Twisted Pair (IBM, Proteon, U-B, etc) Most of the popular token ring implementations use twisted pair. Both IBM and Proteon. o Bridging Token Rings to 802.3 LAN Bridging has a very funny meaning with regard to source routing packets and route discovery in the IBM Token Ring environment. However, some products are already available to route IP packets between token rings and Ethernets. o Bridging VAXen to Fiber Optic Token Ring (IBM or Proteon) Proteon has made UNIBUS boards for their token ring. I'm not sure if an IBM Token Ring is available. Again if it's IP traffic you could use Ethernet on the VAX gatewayed to token ring. o Use of shielded vs. unshielded cable Proteon requires shielded cable (they signal the wirecenter using a DC voltage on the diferential pairs and use the shield as a reference. IBM specs unshielded twisted pair in some circumstances for the older 4 MB TR, but they are now pretty much recommending shielded everywhere. o Use of fiber to the faceplate (single mode or multi mode) Fiber is still pretty costly, mostly because the units at the end are expensive, but that's likely to come down in time. You probaby want multimode. Single mode is much too costly for the purpose of running to individual workstations. -Ron
jbvb@VAX.FTP.COM (James Van Bokkelen) (06/20/89)
Date: 19 Jun 89 17:43:14 GMT From: Patrick Ciriello II <usc!polyslo!vlsi3b15!lehi3b15!lafcol!ciriello@apple.com> ... o Bridging Token Rings to 802.3 LANs You can't. Period. No way. First of all, the bridge would need to handle RIF fields on the 802.5 side, somehow stuffing them into each packet from the 802.3 side. Now, given a sufficiently energetic bridge manufacturer, and a sufficiently small 802.5 LAN, you could build a bridge which found out who was where, but I don't think it would be loveable. Second (and fatal), 802.5 is an MSB LAN, and 802.3 is an LSB LAN. On MSB LANs a MAC-layer address is sent in one bit-order in the header, and the opposite bit-order when sent as data. On LSB LANs, the bit-order is the same in header and data. Thus, while a bridge can fix up the bit-order of the MAC addresses easy as pie, it can't know which data may be a MAC address (e.g. in ARP packets, or network managment systems), so it can't treat it specially. End of story, thanks IBM. See a paper by Roger Pfister of BICC Data Networks entitled "Bit Ordering in MSB and LSB LANs", presented to the ISO FDDI working group last year, for more detail (I can post it if people want). o TCP/IP in a Token Ring environment Works fine. IBM does it on AIX, DOS and mainframes, Proteon, cisco and IBM sell routers with 802.5 interfaces, we sell a DOS 802.5 TCP/IP, Sun has promised 16Mb ring support. See RFC 1042 for how to encapsulate IP. ... James B. VanBokkelen 26 Princess St., Wakefield, MA 01880 FTP Software Inc. voice: (617) 246-0900 fax: (617) 246-0901