Description
Hi,
we are now evaluating the impact of docker 1.13 over our application
Our application is composed of several nodejs microservices and mongodb in replicaset mode.
For this evaluation we are executing some load tests, simulating 1400 concurrent users.
Everything worked fine until we enabled the encryption of the overlay network :(
it seems that services are not able to reach each other anymore!

To make it easier to debug for you, we have found a simple way to reproduce the issue

Steps to reproduce the issue:

1. create 2 networks overlay ; one with encryption enabled and the second one without the encryption:

docker network create --driver overlay  --subnet 192.168.1.0/24 --attachable --opt encrypted encrypted_network
docker network create --driver overlay  --subnet 192.168.1.0/24 --attachable clear_network

2. create a image using the following docker file:

FROM ubuntu:14.04
RUN apt-get update
RUN apt-get -y install wget

3. Deploy the image on 2 different hosts using the not encrypted network with the command :
   docker run --network clear_network -t -i <IMAGE_NAME> /bin/bash

4. start a netcat server listening on port 12345 in one of the containers :
   nc -l 12345

5. Send text using netcat from the second container using the command :
   echo "some text"| nc 192.168.1.3 12345
   The IP is the one of the first container

6. The text is sent from the second to the first container.
   If you repeat these steps using the encrypted overlay network it will not work :(