STGEORGE@UNMB.BITNET (08/30/89)
Is anyone familiar enough with either of these two products, used to transport Decnet over tcp/ip, to give an evaluation? Thanks in advance.
dcrocker@AHWAHNEE.STANFORD.EDU (Dave Crocker) (08/30/89)
DBridge sounds probably refers to one of the options that you can get with the VMS TCP/IP from The Wollongong Group. It permits IP to operate over DECNet, rather than permitting DECNet to operate over IP; my last indication was that that their VMS product is not yet shipped with the latter capability. Multinet is the name of another VMS TCP/IP, developed at SRI International, and I believe still distributed by them to some lucky folks, but perhaps not, since it (also?) is sold by TGV, an SRI "spinoff". I believe that they, too, can do DECNet over TCP/IP but are not yet shipping IP or DECNet. No doubt the TWG and TGV folks will be quick to correct any errors in the above. Dave Crocker Digital Equipment Corp.
adelman@TGV.COM (Kenneth Adelman) (08/31/89)
> DBridge sounds probably refers to one of the options that you can get with > the VMS TCP/IP from The Wollongong Group. It permits IP to operate over > DECNet, rather than permitting DECNet to operate over IP; my last > indication was that that their VMS product is not yet shipped with > the latter capability. One comment about DBRIDGE. It is correctly credited to Van Jacobson and Craig Leres of the Lawrence Berkeley Laboratory. You can FTP sources to it from FTP.EE.LBL.GOV in their anonymous directory. DBRIDGE is an excellent example of how a customer can add a customer-specific transport to either MultiNet or WINS/TCP using the 'rp0' interface. > Multinet is the name of another VMS TCP/IP, developed at SRI International, > and I believe still distributed by them to some lucky folks, but perhaps > not, since it (also?) is sold by TGV, an SRI "spinoff". I believe that > they, too, can do DECNet over TCP/IP but are not yet shipping IP or > DECNet. MultiNet is distributed principally by TGV, SRI, and Excelan. MultiNet implements DECnet over IP, and IP over DECnet in two different ways: 1) Using DBRIDGE to allow customers to make connections to WINS/TCP sites. The disadvantage of using DBRIDGE is that there is a VMS process which must be brought into context once for each packet which comes or goes over the DECnet. 2) Using the ALTSTART interface into the VMS NETDRIVER. This allows us to pass the IP packets to DECnet without having a VMS process in the way. Although the encapsulation is not compatible with DBRIDGE, the performance is much greater and the system overhead much less. Kenneth Adelman TGV, Incorporated
medin@NSIPO.NASA.GOV ("Milo S. Medin", NASA ARC NSI Project Office) (08/31/89)
Speaking as a site which used to run dbridge (a skeleton in my closet), I can assure you that you don't want to do that unless it's really the only way. The performance is not very good, and is much worse that DECNET over IP. The reason is that in current software releases of VMS, you can't get at the raw datagram layer of DECNET, so you have to set up a TCP level DECNET connection and throw IP packets down that pipe. In the other case (DECNET over IP), the DECNET packets are wrapped up in UDP packets and sent with very little overhead. I believe MultiNet is shipping production versions of both now. I thought TWG was as well (my experience with dbridge was years ago using TWG software)... Thanks, Milo