Thank you foryourfeedback Yes,the KLH10istancesall run on thsame Linux Mint
host that runs the apydecanet router calledKSKAL,and I haveno additioal
hardware on that internal segment which lookslike this now:

oot@kaskal:/home/andersa# brctl show
bridge name    bridge id        STP enabled    interfaces
bridge0        8000.26d039e4c0f4    no        tap1
                            tap2
                            tap3

If that doesn't indicate that thethreetap interfaceshavbeen addedto
the bridge,I don't know what does. Are there any other diagnostics you
want me to check? I dont know whether the following add anything relevant:

root@kaskal:/home/andersa# ifconfig bridge0
bridge0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.9.78  netmask 255.255.255.0  broadcast 192.168.9.255
        inet6 fe80::4cf6:1fff:fe01:f257  prefixlen 64  scopeid 0x20<link>
        ether 26:d0:39:e4:c0:f4  txqueuelen 1000  (Ethernet)
        RX packets 557072  bytes 143985475 (143.9 MB)
        RX errors 0  dropped 450854  overruns 0  frame 0
        TX packets 106193  bytes 4586565 (4.5 MB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

root@kaskal:/home/andersa# ifconfig tap1
tap1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet6 fe80::6032:eff:fedb:7b94  prefixlen 64  scopeid 0x20<link>
        ether 62:32:0e:db:7b:94  txqueuelen 1000  (Ethernet)
        RX packets 176227  bytes 46414104 (46.4 MB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 318825  bytes 90356527 (90.3 MB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

root@kaskal:/home/andersa# ip tuntap show
tap0: tap persist
tap1: tap
tap2: tap
tap3: tap

The threeTOPS-20 hosts arealso awareof and can communicate with each
other. When I run tcpdump -i bridge0 I do see DECnet, DEC LAT and TCP/IP
ARP traffic to or from the three TOPS-20 hosts pass by,according to the
ethertype code as well as decoding done by tcpdump.

The KLH10 instances obtain their tap interfaces as part of their
startup configuration, so I have to restart them whenever I have reset
the bridge which I haven't done in a few days now. This is a sample net
device onfiguration line from one host:

devdef ni0  564   ni20 dedic=true ifc=tap2 ifmeth=tap+bridge ipaddr=192.168.9.72
 dpdelay=3


The number of the interface specified with ifc= doesn't seem to matter the machine
still gets assigned the next unassiged tap interface in order.And it did work previously.

Eventually I hope to put all the bridge and pydecnet configuration into a
hecnet.service file andstart it from systemd.

Now I plan to restartpydecnet while logging bridg0 traffic using tcpdmpto see
what comes up.

 /AndersAndersson