Docker Networking across a swarm

General
1

Hello Guys,

Before I go into this yes I have searched this and I do not understand unfortunately. I am not a real networking guy per se.

I was wondering how I would go about sharing a network segment across all 5 nodes of my swarm I am creating it this way right now:
docker network create -d macvlan -o parent=eth0 --subnet 192.168.10.0/24 --gateway 192.168.10.1 --ip-range 192.168.10.192/27 CFSNET but I am having to do that on every node. Then I got to thinking that the range would allow IPs to be duplicated because they would be independent of each node there for on host1 you could have a .32 and on host3 you could have a .32. I hope this is clear. I just need to understand which driver I use to spread the ip range across all 5 nodes collectively and not get duplicate ips on my containers?

I see this when I type docker network ls
network-overlay-ingress

I am suspecting I will have to do something similar

Thanks for your help,
Michael

2

If you create an overlay network on any mater, the network will be created for you on each node that has a container/task connected to it.

Never tried it with macvlan though, not sure if it behaves the same like overlay networks.
Though, I actualy never needed macvlan… not even in the more complex setups I did so far…

3

I am pretty sure it doesn’t and won’t let you do that, after reading some more I believe I would have to create a bridge and do my ip range in that fashion. I am just not a network guy so this is going to be a challenge for me.

Thanks for your response,
Michael

4

I think I just found my own answer and since I had to search for this for a couple of hours, I figured I would share it here with everyone. Apparently overlays don’t allow more than 256 IP addresses there for you have to split them into subnets with /25 or what ever it is you want to use. So, the way I am planning it, is to use one /25 and 2 - /26s This should get me where I need to be of course this is the format it has to be in:

docker network create -d overlay \
  --subnet=192.168.1.0/25 \
  --subnet=192.170.2.0/25 \
  --gateway=192.168.1.100 \
  --gateway=192.170.2.100 \
  --aux-address="my-router=192.168.1.5" --aux-address="my-switch=192.168.1.6" \
  --aux-address="my-printer=192.170.1.5" --aux-address="my-nas=192.170.1.6" \
  my-multihost-network

source: Docker Documentation

Like I said I am not a network guy, I will have to experiment to get this right. I am thinking this would have to be the way it needs to be defined, something of this sort anyway. I hope this helps someone else as well.

Thanks,
Michael