EC0N@TE.CC.CMU.EDU (Eric R. Crane) (08/07/86)
Well, it took many hours of beating my head against a wall, but I was finally able to fix my communications problem. The cause was that we had set the executors MAXIMUM ADDRESS to 512. I did not use much logic in finding this, it was a stab in the dark after logging gave me the error "Adjacent node block size to small". Setting the MAXIMUM ADDRESS back to 255 cause the Vax to talk to the 20 again. For those of you with 20's and Vaxen who do not have plans to sink money into NI20's because your Tops-20 systems are not going to be here much longer you might want to remember this when planning your DECnet networks. For those of you who have burnt the midnight oil learning everything you can (dare?) about DECnet. Is this a bug? Did I miss something in the documentation? Should I SPR it? - Eric R. Crane Carnegie Mellon Computation Center -------
sy.Ken@CU20B.COLUMBIA.EDU (Ken Rossman) (08/07/86)
Well Eric, I'm glad it took you only "many hours" to find your DN20-VAX DECnet link problem. We spent four months on this one and finally gave up when our Ethernet connection to the VAX in question came in... /Ken -------
blinn@FURILO.DEC.COM (Dr. Tom @ MRO3-3 pole T14, 297-5562) (08/10/86)
The restriction on maximum address to 255 when the remote node is a TOPS-20 system being front-ended by a DN20 is a restriction caused by the software in the DN20. If you check out your generation of the DN20 software, I bet you'll find that you set that limitation (probably by default) when you built the software. I'm not sure you can set it any larger than 255 at the DN20 end (but you're welcome to try). This should be documented. If it's not, submit an SPR. But don't expect the DN20 software to get changed -- just the documentation. Are you sure you really hadn't changed ANY software at the VAX end just before this problem surfaced, including the DECnet parameters? In stating that "no software changed", it's important to remember that a change to the parameter tables for parameter driven software (like DECnet) is equivalent to changing the software.