E7OPDAN@TOWSONVX.BITNET (Dan Dinkin) (12/04/87)
Fellow Netlanders, At the request of the Computer Science faculty here, I am about to hookup 4 non-LAT hosts to an Ethernet which already carries our VAXcluster and a MicroVAX II (under Ultrix). These non_lat hosts will be connected to a DECserver 200/MC. I have no problems with that except that the COSC dept. also wants some of these non-LAT hosts to have bi-directional ports on the DECserver. Following the manual, I can set up the hosts, but so far I haven't been able to find anything that talks about making them bi-directional. Normally, the port would have to be set up REMOTE. Does it need to be changed to be DYNAMIC? Or am I missing something entirely? +---------------------------------------------------------------------------+ | Daniel A. Dinkin Towson State University, Academic Computing Service | | Networking Manager 28 Cook Library, Towson, MD 21204 (301) 321-4085 | | | | Bitnet: E7OPDAN@TOWSONVX | | | | Those who do not look to the future, | | Are doomed to live in the pasture. | | | +---------------------------------------------------------------------------+
gil@icus.UUCP (12/06/87)
In article <8712042158.AA23634@ucbvax.Berkeley.EDU> E7OPDAN@TOWSONVX.BITNET (Dan Dinkin) writes: > >At the request of the Computer Science faculty here, I am about to hookup >4 non-LAT hosts to an Ethernet which already carries our VAXcluster and >a MicroVAX II (under Ultrix). These non_lat hosts will be connected to >a DECserver 200/MC. I have no problems with that except that the >COSC dept. also wants some of these non-LAT hosts to have bi-directional >ports on the DECserver. Following the manual, I can set up the hosts, >but so far I haven't been able to find anything that talks about making >them bi-directional. Normally, the port would have to be set up REMOTE. >Does it need to be changed to be DYNAMIC? Or am I missing something >entirely? > No, in fact you hit the nail on the head. The DECserver ports are set to one of three access modes: local (port-to-host), remote (host-to-port), or dynamic (bidirectional). Once the server port has been DEFINEd in this manner (you must use DEFINE to set it in the permanent database, then reset the port by logging it out), you can then (with the proper LAT software) access the port from the host as a normal terminal port. Since this is comp.os.vms, I'll be a little wordy about the use of LAT-plus, and LAT (under VMS 4.6, LAT-plus is no longer needed) and some of the restrictions under VMS. To begin with, the port must be defined as an applications port through LAT before you can use it for any outgoing communications. You do this by executing LATCP and defing a LTAx: device as an application port, and then SETting the port to point to the port on the DECserver. There seems to be several serious restrictions on using remote ports though: First off, if someone is controlling the port in LOCAL mode, the host has no way (at least as far as I have seen) to know if the port is available, and the application will just hang if you try to use that port when someone is using it locally. Secondly, the remote speed of the line is fixed. You cannot say SET TERMINAL/SPEED=x LTAy: and expect it to work. Unless someone has found the answer to this and didn't share it with me on the net (I asked about this some time back), then it is impossible. So far, DEC seems to agree with that statement. Anyhow, this means that using a multi-speed modem on a DECserver port remotely will be restricted to your favorite speed, or the one that the DECserver port is defined as. According to the VMS 4.6 release notes, some terminal functions are now supported on remote LAT ports. Speed doesn't seem to be one of them. I hope this is as much of a help to others as it will be for Dan. I know that when I first tackled the DECserver problems at our shop, I was pretty unfamiliar with their operation. Some of it is still a mystery to me. I would like to have more access to remote functions, but it seems DEC has left much of that functionality in their proprietary code. If anyone else has done LAT programming on a systems-level, I'm sure we'd all like to hear what you have discovered. =============================================================================== Gil Kloepfer, Jr. ...ihnp4!icus!gil Senior Programmer (or whatever path works best Bowne Management Systems, Inc. on the day you reply!) Mineola, NY (516) 248-6840 ext 796 ===============================================================================
tedcrane@batcomputer.tn.cornell.edu (Ted Crane) (12/09/87)
In article <163@icus.UUCP> gil@icus.UUCP (Gil Kloepfer Jr.) writes: >that port when someone is using it locally. Secondly, the remote speed of >the line is fixed. You cannot say SET TERMINAL/SPEED=x LTAy: and expect >it to work. Unless someone has found the answer to this and didn't share >it with me on the net (I asked about this some time back), then it is >impossible. So far, DEC seems to agree with that statement. Anyhow, >this means that using a multi-speed modem on a DECserver port remotely >will be restricted to your favorite speed, or the one that the DECserver >port is defined as. The DECserver 200, at least, supports multispeed modems. You can indicate a port speed and an alternate port speed. The DECserver will monitor one of the data lines coming from the modem and fall back to the slower speed if requested. Now the bad news: as of the last time I tried it, the code to handle fallback speeds did not work correctly with a DF224 modem. Apparently the modem was not following its own spec as to signals and *even if it did* the software in the DECserver was making boo-boos of its own. It was necessary to issue privileged local commands to the DECserver to properly use a multi-speed modem. I'd appreciate an update on this situation if anyone knows of a fix or work- around.