cain@EDN-UNIX.ARPA (Edward A. Cain) (08/13/87)
Is there a commercial product (gateway) which supports ethernet multicast? Needs to take an IP datagram from Arpanet, recongize that the IP address is really a group address, and multicast it onto an ethernet. Ed Cain
martillo@athena.mit.edu (Yakim Martillo) (08/16/87)
In article <8708131534.AA14351@ucbvax.Berkeley.EDU> cain@EDN-UNIX.ARPA (Edward A. Cain) writes: >Is there a commercial product (gateway) which supports ethernet multicast? >Needs to take an IP datagram from Arpanet, recongize that the IP address >is really a group address, and multicast it onto an ethernet. >Ed Cain I believe that for hosts directly connected to an IMP via 1822 IP addresses uniquely identified the IMP interface to which a host is connected. The unique mapping of hardware interface to IP address is quite natural in this case. When TCP/IP moved onto ethernet, the mapping of IP address to physical interface was maintained though for a multihomed host with a separated IP address on each network (of any type of communications subnet) there should be no problem with handling an IP packet on any interface with any IP address as long as IP processing is done in the host or as long as the communications controllers can communicate with one another over the backplane as is possible with DEC machines. Also when people began putting PCs onto ethernets, dynamically assigning IP addresses to PCs seems to be quite reasonable. Further when ISDN interfaces become available, dynamically assigning IP addresses to sets of switched physical or virtual circuits will probably make sense (especially for certain cases of security). Thus my questions are: Is there such a thing as an IP *group* address and if there is what is it used for? Next if there are IP group addresses how do they work in an internetting environment. If there are IP group addresses, does it make any sense to map them to ethernet multicast addresses (which I guess would be assigned to groups of hosts dynamically) and if it does how would one go about handling multinetwork IP group addresses for which multicasting would be clearly insufficient.
CERF@A.ISI.EDU (08/16/87)
You should look into host group multicast - see Bob Braden or the RFCs for details. Vint Cerf
postel@ISI.EDU (08/16/87)
See RFCs 966 and 988. --jon.
braden@ISI.EDU (08/17/87)
Is there such a thing as an IP *group* address and if there is what is it used for? Next if there are IP group addresses how do they work in an internetting environment. If there are IP group addresses, does it make any sense to map them to ethernet multicast addresses (which I guess would be assigned to groups of hosts dynamically) and if it does how would one go about handling multinetwork IP group addresses for which multicasting would be clearly insufficient. Please see RFC988 for the definition of IP group addresses. Although it is not yet an Internet standard, it is likely to become one soon. Experimental implementations for 4.3BSD are available, as previously announced on this list. Bob Braden