spanneti

Spanneti

Spans networks, creating a spaghetti of connections.

Description

Spanneti listens for specially-tagged containers, and builds container networks based on those tags. It was specifically designed to set up VNF chains, so it currently supports point-to-point L2 links (on a single host, or between multiple hosts), and OLT setup (s-tag/c-tag interfaces for the currently-limited tag-forwarding of ONOS).

Environment Setup

You will likely want a functioning container management system. For now, k8s is used as the reference implementation. Documentation for this is available elsewhere, try kubeadm or kubernetes-the-hard-way In addition, you will need:

• A pre-defined fabric interface on each host, which spanneti will use when creating networks.
• A DNS entry which spanneti can use for peer discovery. In the k8s.yml, this is done for you, by creating a Service.

Install

Apply Spanneti to K8s Cluster

Type kubectl apply -f k8s.yml on master node to deploy spanneti. (You may want to pin the version)

After deploy, you can use following commands to check status of spanneti.

Check Spanneti Service

kubectl get services

The result should look like:

NAME         CLUSTER-IP   EXTERNAL-IP   PORT(S)    AGE
kubernetes   10.96.0.1    <none>        443/TCP    9d
spanneti     None         <none>        8080/TCP   9d

Check Spanneti Pods

kubectl get pods

The result should look something like: (with one entry per node in the cluster)

NAME                        READY     STATUS    RESTARTS   AGE
spanneti-b6bc3              1/1       Running   4          9d
spanneti-zz0rz              1/1       Running   5          9d

The status of each spanneti pods should be Running.

TODO: Deploy in a swarm cluster using a docker-compose.yml file.

Usage

As mentioned above, spanneti builds container networks based on tags.
In order to network containers, metadata will need to be added by specifying:

• a container label com.opencord.network.graph={tag-format}, or
• an environment variable OPENCORD_NETWORK_GRAPH={tag-format}

Tag Format

{"olt": {
    "<ethName>": {
        "s-tag":<sTag>,
        "c-tag":<cTag>
    },
    ...
  },
  "links": {
    "<ethName2>":"<link_ID>",
    ...
}}

(olt section is implemented by the olt plugin, links section is implemented by the link plugin)

Basic Example

In this example, we will run two containers, and spanneti will setup a point-to-point (L2) link between those two containers.

This example was created from this demo video.

Watch spanneti log

Type kubtctl log -f spanneti-xxxx to follow a spanneti instance's logs.

Create containers

Run following commands on any nodes which run a spanneti Pod. docker run --name=e1 -d --restart=always --label=com.opencord.network.graph=\{\"links\":\{\"iface0\":\"UUID-1\"\}\} --net=none hwchiu/netutils sleep 100000
docker run --name=e2 -d --restart=always --label=com.opencord.network.graph=\{\"links\":\{\"iface0\":\"UUID-1\"\}\} --net=none hwchiu/netutils sleep 100000
Now. spanneti will connect that two containers (e1,e2) together because they has the same tag (UUID-1)

Testing

You can use following command to verify point-to-point network.

docker exec -it e1 ping 8.8.8.8 -I iface0, the container e1 will send packets via its iface interface.
docker exec -it e2 tcpdump -i iface0 and you will see ARP request issued from container e1.

Note that the ping will not get replies, as there is no DHCP service running in these containers.

Configuration

Environment variables can be changed in the k8s deployment file.

• DNS_NAME - name of the dns entry to lookup for peer discovery
• HOST_INTERFACE_NAME - name of the interface on which to setup networking