[HECnet] Multinet peerings...?

On 2016-01-14 21:02, Peter Lothberg wrote: What I realized when I was working with Steve this Sunday was that in many cases, the biggest performance hit comes if you have several area routers and use the bridge. For most other purposes, as long as you stay consistent, you should be good. The bridge is actually not a performance problem itself, as such. However, anyone talking to MIM will suffer, and will continue to suffer, as long as they use the bridge. Bridge performance should be equal to the Multinet links in general. And, of course, if you are communicating between nodes in the same area, the bridge should even be better than the Multinet links. The situation where you loose is when you go from one area to another, and you have several area routers on the same ethernet segment you yourself are on. In this situation, DECnet will pick the highest numbered node in the remote area, and use that as the next hop to the area. Now, in HECnet, area 1 have three area routers. MIM, PONDUS and JOCKE. While most people would like to talk to MIM, if they talk with area 1, they will always be routed through JOCKE or PONDUS, since those two machines have higher numbers. In the past, only PONDUS was the additional area router, and PONDUS is a real PDP-11/93. Not the fastest machine around. In addition, PONDUS and JOCKE are located in Switzerland, while MIM is in Sweden. So, anyone outside of area 1 trying to talk to MIM over the bridge would send the packets to PONDUS, in Switzerland, and PONDUS would then send the packets back out on the same bridge to get to MIM. Responses back would go direct, as MIM would, on its own, know where to route the packets returned. But this is pretty suboptimal. And there isn't much we can do about it. That is the way DECnet works. It would be wonderful to be able to point to MIM as being the primary area router for area 1, but DECnet only have this concept for intra-area deignated routers on an ethernet. That's where the router priority is used. But for areas, no such thing exists. Obviously, in the old days, you would not expect people on the same ethernet segment to actually be in different areas, so it was probably never thought much about. But that is exactly the scenario the bridge creates. And, obviously, the solution is to actually have ptp-links between areas instead. And I'm working on it. However, I have hit some obscure bug in my code related to multiprocessor RSX internals, which I'm still trying to figure out. Once that is solved, I'll start actually getting these links running on mim, and people in other areas can optionally stop using the bridge to area 1, which will improve life. As for cost tweaking for other areas (areas without multiple area routers that is), I do not believe that tweaking the costs to favor Multinet links will improve life. But I'm interested to hear theories that claims otherwise, and we can try figuring out if they make sense. Johnny