rpw3@rigden.wpd.sgi.com (Rob Warnock) (06/09/90)
In article <8335BA51047F00029B@VAXF.COLORADO.EDU> LISCHKA_J@CUBLDR.COLORADO.EDU writes: +--------------- | I'm designing a network in which a host running UNIX System 5 and | using TCP-IP over Ethernet sends the same message to 16 | workstations. Rather than send the same message 16 times, would | like to broadcast the message to the workstations only once. | Can't use UDP because the workstations have to acknowledge | receipt of the update. Do you know if there are any flavors of | VMTP that will do what I need? +--------------- Don't know about VMTP, but the reliable multicast mode in XTP does exactly that. Depending on how you twiddle the policy knobs, the mechanism supports the range of multicast from "fire-n-forget" datagrams (NOERROR) at one end of the spectrum, through "mostly" reliable datagrams and streams ("mostly" here means "as good as you want" depending on how many retransmission buffers are kept) in the middle to "completely reliable" (positive acknowledgement from each host that the data has been delivered all the way up to the user process) datagrams and streams at the other end. The "mostly reliable" mode can offer an arbitrarily low error rate without requiring a reliable (or indeed *any*) group membership protocol. The "completely reliable" mode does require an external method of determining group membership. Code for XTP is still under development, and is shared on an ongoing basis with XTP Technical Advisory Board (TAB) members and Research Affiliates (RA's). The most recent release [March 1990] of the Unix-based XTP Kernel(-resident) Reference Model (KRM) included an implementation of the "mostly reliable" multicast mode. For more information about participating, or for a current "press kit", please write/call/email/fax: Larry Green, President Phone: (805)965-0825 Protocol Engines, Inc. FAX: (805)687-2984 1900 State Street, Suite D Email: green@pei.com Santa Barbara, CA 93101 or xtp-request@pei.com The press kit includes the XTP Protocol Specification, Revision 3.4 (17 July 1989), but be sure to ask for it explicitly anyway. -Rob ----- Rob Warnock, MS-9U/510 rpw3@sgi.com rpw3@pei.com Silicon Graphics, Inc. (415)335-1673 Protocol Engines, Inc. 2011 N. Shoreline Blvd. Mountain View, CA 94039-7311