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| -rw-r--r-- | docs/release/userguide/docker-ipv6-simple-cluster-topology.rst | 118 | ||||
| -rw-r--r-- | docs/release/userguide/images/docker-ipv6-cluster-example.png | bin | 0 -> 32671 bytes | |||
| -rw-r--r-- | docs/release/userguide/images/routed-network-environment.png | bin | 0 -> 75374 bytes | |||
| -rw-r--r-- | docs/release/userguide/index.rst | 6 |
4 files changed, 122 insertions, 2 deletions
diff --git a/docs/release/userguide/docker-ipv6-simple-cluster-topology.rst b/docs/release/userguide/docker-ipv6-simple-cluster-topology.rst new file mode 100644 index 0000000..c462bc7 --- /dev/null +++ b/docs/release/userguide/docker-ipv6-simple-cluster-topology.rst @@ -0,0 +1,118 @@ +.. This work is licensed under a Creative Commons Attribution 4.0 International License. +.. http://creativecommons.org/licenses/by/4.0 +.. (c) Prakash Ramchandran + +=================================== +Docker IPv6 Simple Cluster Topology +=================================== + +Using external switches or routers allows you to enable IPv6 communication +between containers on different hosts. We have two physical hosts: Host1 & +Host2, and we will study here two scenarios: one with Switch and the other +one with router on the top of hierarchy connecting those 2 hosts. Both hosts +host a pair of containers in a cluster. The contents are borrowed from +article [1]_ below, which can be used on any Linux distro (CentOS, Ubuntu, +OpenSUSE etc) with latest kernel. A sample testing is pointed in the blog +article [2]_ as a variation using ESXi & older Ubuntu 14.04. + +---------------------------- +Switched Network Environment +---------------------------- + +Using routable IPv6 addresses allows you to realize communication between +containers on different hosts. Let’s have a look at a simple Docker IPv6 +cluster example: + +.. figure:: images/docker-ipv6-cluster-example.png + :name: docker-ipv6-cluster-figure1 + :width: 100% + + Figure 1: An Docker IPv6 Cluster Example + +The Docker hosts are in the ``2001:db8:0::/64`` subnet. Host1 is configured to +provide addresses from the ``2001:db8:1::/64`` subnet to its containers. It has +three routes configured: + +* Route all traffic to ``2001:db8:0::/64`` via eth0 +* Route all traffic to ``2001:db8:1::/64`` via docker0 +* Route all traffic to ``2001:db8:2::/64`` via Host2 with IP ``2001:db8:0::2`` + +Host1 also acts as a router on OSI layer 3. When one of the network clients +tries to contact a target that is specified in Host1’s routing table, Host1 +will forward the traffic accordingly. It acts as a router for all networks it +knows: ``2001:db8::/64``, ``2001:db8:1::/64``, and ``2001:db8:2::/64``. + +On Host2, we have nearly the same configuration. Host2’s containers will get +IPv6 addresses from ``2001:db8:2::/64``. Host2 has three routes configured: + +* Route all traffic to ``2001:db8:0::/64`` via eth0 +* Route all traffic to ``2001:db8:2::/64`` via docker0 +* Route all traffic to ``2001:db8:1::/64`` via Host1 with IP ``2001:db8:0::1`` + +The difference to Host1 is that the network ``2001:db8:2::/64`` is directly +attached to Host2 via its docker0 interface, whereas Host2 reaches +``2001:db8:1::/64`` via Host1’s IPv6 address ``2001:db8:0::1``. + +This way every container can contact every other container. The containers +Container1-* share the same subnet and contact each other directly. The traffic +between Container1-* and Container2-* will be routed via Host1 and Host2 +because those containers do not share the same subnet. + +In a switched environment every host must know all routes to every subnet. +You always must update the hosts’ routing tables once you add or remove a host +to the cluster. + +Every configuration in the diagram that is shown below the dashed line across +hosts is handled by Dockeri, such as the docker0 bridge IP address +configuration, the route to the Docker subnet on the host, the container IP +addresses and the routes on the containers. The configuration above the line +across hosts is up to the user and can be adapted to the individual environment. + +-------------------------- +Routed Network Environment +-------------------------- + +In a routed network environment, you replace the layer 2 switch with a layer 3 +router. Now the hosts just must know their default gateway (the router) and the +route to their own containers (managed by Docker). The router holds all routing +information about the Docker subnets. When you add or remove a host to this +environment, you just must update the routing table in the router instead of on +every host. + +.. figure:: images/routed-network-environment.png + :name: docker-ipv6-cluster-figure2 + :width: 100% + + Figure 2: A Routed Network Environment + +In this scenario, containers of the same host can communicate directly with +each other. The traffic between containers on different hosts will be routed +via their hosts and the router. For example, packet from Container1-1 to +Container2-1 will be routed through Host1, Router, and Host2 until it arrives +at Container2-1. + +To keep the IPv6 addresses short in this example a ``/48`` network is assigned +to every host. The hosts use a ``/64`` subnet of this for its own services and +one for Docker. When adding a third host, you would add a route for the subnet +``2001:db8:3::/48`` in the router and configure Docker on Host3 with +``--fixed-cidr-v6=2001:db8:3:1::/64``. + +Remember the subnet for Docker containers should at least have a size of +``/80``. This way an IPv6 address can end with the container’s MAC address and +you prevent NDP neighbor cache invalidation issues in the Docker layer. So if +you have a ``/64`` for your whole environment, use ``/76`` subnets for the +hosts and ``/80`` for the containers. This way you can use 4096 hosts with 16 +``/80`` subnets each. + +Every configuration in the diagram that is visualized below the dashed line +across hosts is handled by Docker, such as the docker0 bridge IP address +configuration, the route to the Docker subnet on the host, the container IP +addresses and the routes on the containers. The configuration above the line +across hosts is up to the user and can be adapted to the individual environment. + +---------- +References +---------- + +.. [1] https://docs.docker.com/v17.09/engine/userguide/networking/default_network/ipv6/#docker-ipv6-cluster +.. [2] http://www.debug-all.com/?p=128 diff --git a/docs/release/userguide/images/docker-ipv6-cluster-example.png b/docs/release/userguide/images/docker-ipv6-cluster-example.png Binary files differnew file mode 100644 index 0000000..f299d03 --- /dev/null +++ b/docs/release/userguide/images/docker-ipv6-cluster-example.png diff --git a/docs/release/userguide/images/routed-network-environment.png b/docs/release/userguide/images/routed-network-environment.png Binary files differnew file mode 100644 index 0000000..1d2ef36 --- /dev/null +++ b/docs/release/userguide/images/routed-network-environment.png diff --git a/docs/release/userguide/index.rst b/docs/release/userguide/index.rst index 604574e..f4012a7 100644 --- a/docs/release/userguide/index.rst +++ b/docs/release/userguide/index.rst @@ -26,8 +26,9 @@ some IPv6 related operations. The IPv6 Setup in Container Networking serves as feature specific user guides and references when as a user you may want to explore IPv6 in Docker container -environment. The use of NDP Proxying is also explored to connect IPv6-only -containers to external network. +environment. The use of NDP Proxying is explored to connect IPv6-only +containers to external network. The Docker IPv6 simple cluster topology is +studied with two Hosts, each with 2 Docker containers. For more information, please find `Neutron's IPv6 document for Queens Release <http://docs.openstack.org/neutron/queens/admin/config-ipv6.html>`_. @@ -40,3 +41,4 @@ For more information, please find `Neutron's IPv6 document for Queens Release ./gap-odl-oxygen.rst ./ipv6-in-container-networking.rst ./icmpv6-and-ndp-proxying-for-docker-containers.rst + ./docker-ipv6-simple-cluster-topology.rst |
