[HECnet] TOPS-20 on HECnet?

[Johnny Billquist]

On 2014-01-13 22:45, Mark Abene wrote:
OK, I'm at the hair-tearing-out stage... Who here has a TOPS-20 system
connected to HECnet?   I'm trying to peer with Sampsa with "bridge" in
his same area as an endnode.   Bridge works fine on my end, lots of
activity in debug mode, and I see lots of node number entries if I
send it a SIGUSR1.   However I never "see" the adjacent node in NCP,
though my circuit and line are up and active.   Adding a few nodes
manually with NCP SET NODE and then trying a SET HOST in the monitor
just times out.   If I do this while watching my ethernet with tcpdump,
I see my real DECnet traffic, immediately followed by its encapsulated
udp packet going out over port 4711.   However, I never get any
responses to my SET HOST from the remote bridge side.   Any suggestions
on debugging this?

If you don't have the adjacency status up when looking in NCP, there is no point in trying to do a SET HOST, or anything else, because that depends on the circuit status.

If you see both incoming and outgoing DECnet traffic, and yet don't get the adjacency status up, then there is only one thing I'd want to check.
When looking at incoming packets from a remote system, the bridge will send them out on your local ethernet. Check what the source MAC address is of those packets. If the source MAC is the machine where you run the bridge, then it will not work. I know that some machines and ethernet controllers will not allow you to set the source MAC address yourself, and in that situation, the bridge can never work.

	Johnny