no connectivity to some hosts behind tinc for the first few seconds

[Tomasz Chmielewski]

I have the following tinc setup:

client -- tinc DC1 -- tinc DC2 -- 10.1.2.0/24 subnet


It generally works well, however, there is one issue I'm not able to 
solve: *sometimes*, connectivity to *some* destinations does not work 
for the first few seconds.


To demonstrate:

$ mongo mongo.example.com:27017
MongoDB shell version: 3.2.12
connecting to: mongo.example.com:27017/test
2017-02-21T03:29:30.243+0000 W NETWORK  [thread1] Failed to connect to 
10.1.2.3:27017 after 5000ms milliseconds, giving up.
2017-02-21T03:29:30.243+0000 E QUERY    [thread1] Error: couldn't 
connect to server mongo.example.com:27017, connection attempt failed :
connect at src/mongo/shell/mongo.js:231:14
@(connect):1:6

exception: connect failed


Then connect again immediately after - connection works, once it's 
established, no packet losses:

$ mongo mongo.example.com:27017
MongoDB shell version: 3.2.12
connecting to: mongo.example.com:27017/test
tab:SECONDARY> ^C


Any clues what might be causing this issue? Looks like ARP resolution 
somewhere, but I've not sure how to debug this.

Or not ARP resolution - as it can sometimes be that the first connection 
is successful, and the next one is not, i.e.:

$ echo exit | mongo mongo.example.com:27017
MongoDB shell version: 3.2.12
connecting to: mongo.example.com:27017/test
bye


Some 10-20 secs later (ARP should live longer than that):

echo exit
+ mongo mongo.example.com:27017
MongoDB shell version: 3.2.12
connecting to: mongo.example.com:27017/test
2017-02-21T03:34:55.754+0000 W NETWORK  [thread1] Failed to connect to 
10.1.2.3:27017 after 5000ms milliseconds, giving up.
2017-02-21T03:34:55.754+0000 E QUERY    [thread1] Error: couldn't 
connect to server mongo.example.com:27017, connection attempt failed :
connect at src/mongo/shell/mongo.js:231:14
@(connect):1:6

exception: connect failed




Tomasz Chmielewski
https://lxadm.com