cam@SATURN.ACC.COM (Chris Markle acc_gnsc) (05/31/89)
Folks, A recent article in MIS Week describes an "agreement" between IBM and Ungermann-Bass (UB), 3Com, and Western Digital (WD) to have the three vendors comply with the NDIS (Network Driver Interface Specification) such that OS/2 EE Version 1.2 will support Ethernet adapters from those vendors. The article goes on to mention how the OS/2 EE version of NDIS allows SNA and NetBIOS to operate over an Ethernet LAN. I was curious as to what "allows SNA to operate over an Ethernet LAN" really means. Any thoughts? One thing that bothers me is that SNA presumes that the data link is "reliable" (ie. SDLC, token ring using LLC type 2 operation, and the 370 channel). The "LLC" used with Ethernet is usually type 1 with no link-level acknowledgments, flow control, or error recovery. For SNA to operate over such a "LLC" would require the equivalent of a transport protocol to be used between SNA and the Ethernet link-level. A type 2 "LLC" with reliable characteristics could be used over Ethernet and then SNA run over that. Is this what people are doing or intend to do? (I use "LLC" to represent "an" LLC versus "the" IEEE 802.2 LLC.) Another question is how address resolution is (or will be) accomplished? Send replies to me or to everywhere; it doesn't matter as I read both and will summarize if I get anything worth summarizing. Chris Markle - ACC
stevens@hsi.UUCP (Richard Stevens) (06/15/89)
In article <8905301932.AA26903@saturn.acc.com>, cam@SATURN.ACC.COM (Chris Markle acc_gnsc) writes: > > Another question is how address resolution is (or will be) accomplished? A little known IBM product is their SNA support over an Ethernet for the RT. (I'm not an RT user and this information is dated January 87, so I have no idea about its current status.) I have no idea if this announced PC product is meant to interoperate with this RT product. In the manual "SNA Services Guide and Reference" for the RT AIX V2.1, Appendix D gives the name services provided over an Ethernet. (The manual says "Ethernet" everywhere but the frames they diagram are all 802.3.) They provide 4 services: (1) Add Name Query. You broadcast this to see if any other node has the name you want already registered. Hummmm, sounds like Netbios ... (2) Name Query Response. The response to (1) if someone already has the name. (3) Find Name Request. You broadcast this to locate the physical address corresponding to an 8-byte name you want to contact. (4) Name Found Request. The response to (3) if the name is found. Richard Stevens Health Systems International, New Haven, CT stevens@hsi.com ... { uunet | yale } ! hsi ! stevens