brooks@Apple.COM (Kevin Brooks) (10/02/90)
Does anyone know of a bridge or router that will allow HP hosts running
TCP/IP which speak IEEE style packets (802.2 encapsulated) to
communicate with ethernet style IP implementations? Do most of the
router/bridge vendors support both IEEE and ethernet style IP packets?
Thanks in advance
Kevin
--
Kevin Brooks A/UX Specialist, Apple Computer
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Internet: brooks@apple.comwehr@fmeed1.UUCP (Bruce Wehr) (10/16/90)
In article <45306@apple.Apple.COM>, brooks@Apple.COM (Kevin Brooks) writes: > > Does anyone know of a bridge or router that will allow HP hosts running > TCP/IP which speak IEEE style packets (802.2 encapsulated) to > communicate with ethernet style IP implementations? Do most of the > router/bridge vendors support both IEEE and ethernet style IP packets? I don't have much experience here, but I'm installing a small ethernet network (about a dozen hosts) here at work - and I'm learning while doing. My design includes a bridge in each lab, primarily to aid in fault isolation. The bridge I've chosen is the Retix 2255. The manual says it will pass both style packets transparently, which (I think) answers your second question. It also states that the software on each respective host must deal with packet differences themselves, which (I think) answers your first question (that is, if I understand your first question correctly - you're looking for a bridge that will convert one style packet to another - right? This bridge explicitly *won't* [and I don't know of one that will]. But, it will pass both types, no problem). I hope this helps. -- Bruce Wehr (wehr%dptc.decnet@srlvx0.srl.ford.com) (...uunet!mailrus!sharkey!fmeed1!wehr) (wehr%fmeed1.uucp@mailgw.cc.umich.edu) Ford Motor Company - Electronics Division 17000 Rotunda Drive, ETC Room LN081, Dearborn, Michigan 48121 (313)845-3039
hedrick@athos.rutgers.edu (Charles Hedrick) (10/18/90)
The problem with HP's 802.2 TCP/IP is that it doesn't use the standard 802.2 IP encapsulation. It uses their own homegrown one, which (among other things) uses HP's "probe" protocol instead of ARP. I have no idea why somebody would do a TCP/IP implementation that can't talk to any other TCP/IP implementation, but they did. (Supposedly this was fixed in later releases, though the code we are using on an HP/3000 still seems to be this way.) As far as I know, the only product that will translate between HP's braindamage and normal IP encapsulations is a cisco router. In general there are problems with mapping between IEEE and Ethernet encapsulations. E.g. Appletalk uses IEEE for phase II and Ethernet for phase I. A simple translation would cause Appletalk to get the two phases confused. I believe there are similar problems with other protocols. The net result is that bridges with IEEE/Ethernet translation need interesting options to make everything work. This makes supposedly transparent Ethernet/FDDI bridges a very dicey proposition. (Not that it can't be made to work for many useful cases, but that the obvious mapping causes problems.) But this isn't relevant to the HP case andway, since their IEEE encapsulation isn't standard. So a normal IEEE to Ethernet translation wouldn't help.