jqj@DUFF.UOREGON.EDU (01/31/91)
This message follows up on discussion that appeared on the tcp-ip list in July of last year. There have been some changes since that time: RFC1188 (revising RFC1103 and specifying IP over FDDI) in October, and a meeting of 802.1d in November. I gather from a recent posting by Kevin Brooks of Apple on comp.protocols.appletalk that the 802.1d standard has changed significantly. In particular, it is now apparently generally agreed that "transparent" bridging between Ethernet and 802 media should use a non-zero Protocol ID for (some) Ethernet packets. My question is whether the authors of RFC1188 and 1042 have been involved in this process, and what it implies for the future of IP-over-whatever heterogenous bridging. One possible answer is "no change to IP encapsulation protocols". If an Ethernet->FDDI bridge uses the new non-zero OUI for only a small list of protocols not including ARP and IP, and an FDDI->Ethernet bridge decapsulates (at least IP and ARP) packets with OUI=0, then RFC1188 is unaffected. On the other hand, this might be an opportunity to rethink encapsulation to deal with other problems like MTU mismatches and ARP hardware type codes. It certainly implies that we'll be seeing lots of broken "transparent" bridge implementations, and that we as network trobuleshooters will have lots of new business! JQ Johnson Director of Network Services Internet: jqj@oregon.uoregon.edu University of Oregon voice: (503) 346-4394 250E Computing Center BITNET: jqj@oregon Eugene, OR 97403-1212 fax: (503) 346-4397