[KNX] Too much tunnel connections #5911
Description
I regularly notice that I cannot make a tunnel connection in ETS to the KNX bus anymore. I can resolve this by starting OpenHAB. After restarting, I have no problems for several weeks.
Today I had this issue again and I listed all the UDP connections:
$ sudo netstat -aunp | grep java
udp6 0 0 :::5353 :::* 682/java
udp6 0 0 192.168.0.180:37610 :::* 682/java
udp6 0 0 192.168.0.180:38186 :::* 682/java
udp6 0 0 192.168.0.180:36204 :::* 682/java
udp6 0 0 :::1900 :::* 682/java
udp6 0 0 192.168.0.180:49556 :::* 682/java
udp6 0 0 192.168.0.180:52725 :::* 682/java
Then I restarted OpenHAB. Running the above command gave no results.
During startup, connections were created again:
$ sudo netstat -aunp | grep java
udp6 0 0 192.168.0.180:51413 :::* 25775/java
udp6 0 0 :::5353 :::* 25775/java
udp6 0 0 :::1900 :::* 25775/java
After the KNX binding was initialized, and I started seeing loads of status telegrams in ETS group monitor (which always happens during startup), 1 more connection was created:
$ sudo netstat -aunp | grep java
udp6 0 0 192.168.0.180:51413 :::* 25775/java
udp6 0 0 :::5353 :::* 25775/java
udp6 0 0 :::1900 :::* 25775/java
udp6 0 0 192.168.0.180:33478 :::* 25775/java
So that's 4 UDP connections vs 7 before restart. We can assume at this point there is only 1 for KNX. My KNX IP interface has 4 tunnels, so 3 extra tunnels would mean all tunnels are occupied and any extra (e.g. ETS) cannot be established.
In the OpenHAB knx logging I sporadically see disconnects and reconnects. However sometimes it tries to reconnect multiple times in the same 100ms:
2019-11-06 10:02:00.549 [WARN ] [nx.internal.connection.KNXConnection] - KNX link has been lost (reason: server request on object tunneling link link (closed) 192.168.0.187:3671 TP1 medium, device 0.0.0, hopcount 6)
2019-11-06 10:02:00.553 [INFO ] [nx.internal.connection.KNXConnection] - KNX link will be retried in 30 seconds
2019-11-06 10:02:00.598 [WARN ] [nx.internal.connection.KNXConnection] - KNX link has been lost (reason: server request on object tunneling link link (closed) 192.168.0.187:3671 TP1 medium, device 0.0.0, hopcount 6)
2019-11-06 10:02:00.603 [INFO ] [nx.internal.connection.KNXConnection] - KNX link will be retried in 30 seconds
...
2019-11-06 10:02:30.562 [INFO ] [nx.internal.connection.KNXConnection] - Trying to (re-)connect to KNX...
2019-11-06 10:02:30.615 [INFO ] [nx.internal.connection.KNXConnection] - Established connection to KNX bus on 192.168.0.187:3671 in mode TUNNEL.
2019-11-06 10:02:30.608 [INFO ] [nx.internal.connection.KNXConnection] - Trying to (re-)connect to KNX...
2019-11-06 10:02:30.646 [INFO ] [nx.internal.connection.KNXConnection] - Connected to KNX
2019-11-06 10:02:30.680 [INFO ] [nx.internal.connection.KNXConnection] - Established connection to KNX bus on 192.168.0.187:3671 in mode TUNNEL.
2019-11-06 10:02:30.697 [INFO ] [nx.internal.connection.KNXConnection] - Connected to KNX
Could this be the cause? Or are the old tunnels somehow not released?
Your Environment
OpenHab 2.4.0 Release
binding-knx1 - 1.13.0
Running on Raspberry Pi 3
KNX IP interface: MDT SCN-IP100.02
knx.conf:
ip=192.168.0.187
ignorelocalevents=true
type=TUNNEL
localIp=192.168.0.180
autoReconnectPeriod=30