ken@fibermux.com (Ken Restivo) (06/28/91)
Any idea where I can get some good information comparing Ethernet 1.0 to Ethernet 2.0 and how each compares with 802.3 for purposes of interoperability? I have a copy of the Ethernet 1.0 spec and the IEEE 802.3, and the only difference I can see is in the pinouts and in the SFD and length/type feild. But I see no reason why the two would not be interoperable at the physical layer! Other than the pinout issue, and the fact that 802.3 supports signalling from the DTE to the MAU for mau_request and normal/isolate messages while Ethernet 1.0 leaves these pins unconnected. Thanks.
oberman@ptavv.llnl.gov (06/28/91)
In article <1991Jun27.232020.14010@fibermux.com>, ken@fibermux.com (Ken Restivo) writes: > Any idea where I can get some good information comparing Ethernet 1.0 to Ethernet 2.0 and how each compares with 802.3 for purposes of interoperability? > > I have a copy of the Ethernet 1.0 spec and the IEEE 802.3, and the only difference I can see is in the pinouts and in the SFD and length/type feild. > > But I see no reason why the two would not be interoperable at the physical > layer! Other than the pinout issue, and the fact that 802.3 supports signalling > from the DTE to the MAU for mau_request and normal/isolate messages while > Ethernet 1.0 leaves these pins unconnected. They do interoperate, but there are several differences beyond what you spotted. First, Ethernet V1 has no "heartbeat" or SQE. That's none at all. Heartbeat was added in V2. Since V2 arrived before Ethernet got very popular, there is very little V1 equipment out there. I have yet to find a V1 controller that has even halfway decent performance, so they drop lots of packets. This, in turn, results in lots of packets being retransmitted with serious perfomace hits for the systems involved and a heavier load for the whole net. I'd seriously consider dumping any Ethernet stuff that old. But, if you can't, it will probably interoperate OK with V2 or 802.3 stuff. I should also mention that using V1 controllers with V2 MAUs has caused me some problems. But the inverse is a real no-no! Also, I had lots of problems with V1 fan-outs and V2 equipment. V2 and 802.3 interoperate pretty well. Once again, you shouldn't use a V2 MAU with 802.3 controllers, but I've never actually had any problem doing so as long as repeaters were not involved. V2 repeaters should only be used with V2 MAUs and vice-versa. And also note that SQE (sorts 802.3 heartbeat) should be off for repeeaters. Once again, fan-outs can cause problems. But I've only had them when repeaters are plugged into fan-outs. Other than these caveats, all should interoperate. But I would get rid of any old V1 stuff if possible. R. Kevin Oberman Lawrence Livermore National Laboratory Internet: oberman@icdc.llnl.gov (415) 422-6955 Disclaimer: Don't take this too seriously. I just like to improve my typing and probably don't really know anything useful about anything.