robert@gitpyr.gatech.EDU (Robert Viduya) (01/15/87)
Georgia Tech is currently investigating the possibility of hooking up to the Arpanet and one of the considerations we are faced with is what kind of router is best for hooking up our local TCP/IP Ethernet to a DDN X.25 line. We are looking for either a standalone box or something that will run on a DEC Vaxstation II. What I'm looking for are reviews, critiques, personal experiences, prices and technical information on routers that fit the above criteria. Please mail any info that might be helpful. If I get enough requests, I'll summarize to the net. Thanks. robert -- Robert Viduya robert@pyr.ocs.gatech.edu Office of Computing Services (404) 894-4660 Georgia Institute of Technology Atlanta, Georgia 30332
mangler@cit-vax.Caltech.Edu (System Mangler) (01/16/87)
Has anyone gotten *anything* to work with an X.25 port on
a PSN (aka IMP)? Some local folks have been trying to get
their X.25 ARPAnet connection going for some months now,
so I keep getting the impression that the X.25 stuff is
not exactly debugged yet.
Don Speck speck@vlsi.caltech.edu {seismo,rutgers,ames}!cit-vax!speckmelohn%sluggo@Sun.COM (Bill Melohn) (01/16/87)
Yes, Sun offers a DDN gateway product (Sunlink DDN) which speaks both HDH and X.25 (standard and basic services). While the IMP implementation of X.25 may not have been tuned/debugged as much as the other connection protocols, it does work.
medin@orion.arpa (Milo S. Medin) (01/16/87)
In article <1504@cit-vax.Caltech.Edu> mangler@cit-vax.Caltech.Edu (System Mangler) writes: >Has anyone gotten *anything* to work with an X.25 port on >a PSN (aka IMP)? Some local folks have been trying to get >their X.25 ARPAnet connection going for some months now, >so I keep getting the impression that the X.25 stuff is >not exactly debugged yet. > >Don Speck speck@vlsi.caltech.edu {seismo,rutgers,ames}!cit-vax!speck Don, you're exactly right. If you are running 4.3 and the ACC DDN X.25 board, you can get a relatively fixed driver from Mike Petry (petry@trantor.umd.edu). It's really new as he made a breakthrough recently. Note the ACC driver on the 4.3 tape has some serious problems with it. As does the TWG code for VMS no doubt. My feelings are that for local connections to the IMP (PSN), 1822DH is far superior if you can get an interface from ACC for your system. A straight 1822DH connection will run twice as fast as a comparable X.25 connection simply because the 1822 can signal at about 100-200 Kb/s and you can't connect X.25 to an IMP faster than 64 Kb/s. That may not be important for a host with a few connects open to other DDN hosts, but for a gateway which may be talking to a very large set of other hosts (or gateways) on the network it can make a big difference. I see no technical reason to inflict X.25 and HDLC on a 20 ft cable going between a gateway and the IMP. Also, the DDN X.25 spec is very complicated, as are most of the X.25 interface boards that talk to the IMP. It takes great care and skill to write a good driver for these beasts. Sooner or later we'll no doubt be forced to convert, but that won't be for a couple years at least, and by then we may have more stable drivers and faster signalling to overcome the current problems of the system. Currently there are a lot of hosts on MILNET that use X.25 interfaces, but about 94% don't pass IP with them -- they use DDN BASIC X.25 service (not Standard). All the usual disclaimers apply... Milo "I love 1822" Medin NASA Ames/ Bendix Aerospace
csg@pyramid.UUCP (01/29/87)
In article <168@ames.UUCP> medin@orion.UUCP (Milo S. Medin) writes: >My feelings are that for local connections to the IMP (PSN), >1822DH is far superior if you can get an interface from >ACC for your system. Er, I thought DCA was prohibiting new connections using 1822LH and 1822DH? We have several customers that are being forced to abandon their 1822 interfaces and switch to X.25. <csg>
medin@orion.UUCP (01/30/87)
In article <1498@pyramid.UUCP> csg@pyramid.UUCP (Carl S. Gutekunst) writes: >... >Er, I thought DCA was prohibiting new connections using 1822LH and 1822DH? We >have several customers that are being forced to abandon their 1822 interfaces >and switch to X.25. > ><csg> New connections are strongly encouraged to be Standard Service DDN X.25. But you can still request and get 1822DH connections with a waiver from OSD. I've been told that if you request 1822DH and give fairly good reasons, they'll give it to you, but you shouldn't be timid when doing it. Nobody I know of who has 1822 is having it replaced unless its a long distance connection with ECU's or the like. I should know, our MILNET PSN has something like 7 1822DH connects to it. They all work just fine, which is more than I can say for most X.25 connects. You can send me mail if you'd like to discuss this offline... Milo NASA Ames/Bendix Aero. PS Usual disclaimers apply...