Why does boot2docker, and port forwarding to my docker instances, periodically hang?

I have run the following command to forward sinatra and redis ports to my docker instance running in virtualbox on OSX:

ports=( 4567 6379 )
for port in "${ports[@]}"
echo "Forwarding $port"
VBoxManage modifyvm "boot2docker-vm" --natpf1 "tcpport$port,tcp,,$port,,$port"

However, periodically (like every 60 seconds) requests to either of these docker instances over my machine’s public IP, originating from my machine, will hang for 40-60 seconds. However, my docker instance is healthy and I can connect directly via

Thus, why would a connection such as:

redis-cli -h PING

Periodically hang, but

redis-cli -h PING

Always work? Is there some kind of bug in VirtualBox or boot2docker?

Moreover, during the periods where these requests hang, I have noticed that calls to

boot2docker ip


boot2docker ssh

Themselves both hang. I am running boot2docker 1.6.2 and VirtualBox 4.3.28 on OSX 10.10.3.

Additional debugging reveals that inter-instance connectivity is now impaired as well. I have linked two containers, and periodically HTTP requests between them will hang. I went so far as to run telnet container_name 4567, then I typed


Which, of course, is the most basic way to test a webserver. From inside of container_name, I ran curl http://localhost:4567/. The telnet request hung, but the curl http://localhost:4567/ returned immediately.

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