Calico BIRD Route Reflector container

For many Calico deployments, the use of a Route Reflector is not required. However, for large scale deployments a full mesh of BGP peerings between each of your Calico nodes may become untenable. In this case, route reflectors allow you to remove the full mesh and scale up the size of the cluster.

This guide discusses the calico/routereflector image: a container image that packages up the BIRD BGP daemon along with the confd templating engine to provide a simple route reflector image which may be used for scaled-out Calico deployments.

The image is currently experimental due to some key limitations discussed below. However, it may provide a useful framework for future development.

These instructions are focused around container-based deployments that use the calico/node container image.

For an OpenStack deployment, read Configuring BIRD as a BGP Route Reflector.

Known limitations

  • The calico/routereflector instance will automatically peer with the Calico nodes, but it currently has no mechanism to configure peerings with non-Calico BGP speakers (e.g. edge routers)
  • There is no calicoctl integration or similar - it is necessary to configure data directly into the etcd datastore each time a new route reflector is added to the deployment.
  • Each Route Reflector will form a full mesh between all other Route Reflectors in the cluster. It is not possible to form multiple separate meshed groups of Route Reflectors using this image.

Using the Route Reflector image

Starting a Route Reflector instance

On your Route Reflector host, ensure you have Docker v1.6 or greater installed.

Run the following command to start the Route Reflector container image.

docker run --privileged --net=host -d                              \ 
           -e IP=<IPv4_RR>                                         \
           [-e IP6=<IPv6_RR>]                                      \
           -e ETCD_ENDPOINTS=<http://ETCD_IP:PORT>                 \
           calico/routereflector:master

Where:

  • [] indicates an optional parameter
  • <IPv4_RR> is the IPv4 address of the RR host (the BIRD instance binds to the hosts IPv4 address)
  • <IPv6_RR> is the optional IPv6 address of the RR host (the BIRD6 instance binds to the hosts IPv6 address)
  • <ETCD_IP:PORT> is the colon separated IPv4 address and port of an etcd node in the etcd cluster. A comma-separated list of endpoints may be specified.

Note: If you require TLS/SSL enabled etcd, see the section below for details on how to start the route reflector.

Configuring the Route Reflector

Each Route Reflector instance reads its configuration from etcd (necessarily the same etcdv2 cluster that Calico is using). At present, there is no calicoctl integration to allow you to configure the Route Reflector.
To configure Calico to use the Route Reflector it is necessary to explicitly add an entry into etcd. The etcd configuration serves two purposes: it tells the Route Reflector to participate in peering, and it provides sufficient information to allow all of the Route Reflector instances to automatically form a full BGP mesh.

The configuration for the Route Reflector is stored for IPv4 at:

/calico/bgp/v1/rr_v4/<RR IPv4 address>

and IPv6 at:

/calico/bgp/v1/rr_v6/<RR IPv6 address>

In all cases, the data is a JSON blob in the form:

    {
      "ip": "<IP address of Route Reflector>",
      "cluster_id": "<Cluster ID for this RR (see notes)>"
    }

To add this entry into etcd, you could use the following commands:

# IPv4 entries
curl -L http://<ETCD_IP:PORT>/v2/keys/calico/bgp/v1/rr_v4/<IPv4_RR> -XPUT -d value="{\"ip\":\"<IPv4_RR>\",\"cluster_id\":\"<CLUSTER_ID>\"}"

# IPv6 entries
curl -L http://<ETCD_IP:PORT>/v2/keys/calico/bgp/v1/rr_v6/<IPv6_RR> -XPUT -d value="{\"ip\":\"<IPv6_RR>\",\"cluster_id\":\"<CLUSTER_ID>\"}"

Replacing , , and as required. For example, for a Route Reflector with the values:

  • etcd running at http://192.0.2.10:2379
  • The Route Reflector IP address of 192.0.2.50
  • A Cluster ID of 1.0.0.1

the following command would be used to configure the Route Reflector.

curl -L http://192.0.2.10:2379/v2/keys/calico/bgp/v1/rr_v4/192.0.2.50 -XPUT -d value="{\"ip\":\"192.0.2.50\",\"cluster_id\":\"1.0.0.1\"}"

See below for details about large networks and the use and format of the cluster ID.

Repeat the above instructions for every Route Reflector in the cluster.

Route reflector cluster

When starting a cluster of route reflectors, the Calico BIRD Route Reflector takes care of creating a full mesh between all of the route reflectors in the cluster. When adding a new Route Reflector instance, add an entry into etcd. All Route Reflector instances watch for new Route Reflectors and update their peerings accordingly.

Route reflector peering with Calico Docker nodes

The Calico BIRD Route Reflector image hooks into the same etcd datastore used by the Calico Docker nodes to determine which nodes to peer with.

The peering between the Calico Docker nodes and each route reflector is configured using calicoctl by configuring each Route Reflector as a BGP peer of each node, the route reflector automatically sets up the reverse peering and requires no additional configuration.

Global Calico Docker configuration

Run through this section to set up the global Calico Docker configuration before configuring any nodes. This only needs to be done once.

  • Disable the full node-to-node BGP mesh
  • Configure the default node AS number for your network (this is used by the Route Reflector image when setting up the Route Reflector full mesh).

If you have a small cluster of Route Reflectors and you intend to have every Calico Docker node peer with every Route Reflector, set this up one time as global configuration.

Turn off the full node-to-node mesh

From any Calico Docker node, run the following:

calicoctl config set nodeToNodeMesh off

You may need to set the ETCD_ENDPOINTS environment variable to run the calicoctl commands.

Determine the AS number for your network

From any Calico Docker node, run the following:

calicoctl get nodes --output=wide

This returns table of all configured Calico node instances and includes the AS number for each node.

Peering with every Route Reflector (optional)

If you have a small cluster of Route Reflectors (e.g. a single RR or a pair of RRs for redundancy) and you intend to have every Calico Docker node peer with each of the Route Reflectors, you can set up the peerings as a one-time set of global configuration.

Use calicoctl to configure each route reflector as a global peer (i.e. it peers with every node in the deployment):

calicoctl bgp peer add <IP_RR> as <AS_NUM>
$ calicoctl create -f - << EOF
apiVersion: v1
kind: bgpPeer
metadata:
  peerIP: <IP_RR>
  scope: global
spec:
  asNumber: <AS_NUM>
EOF

Where:

  • <IP_RR> is the IPv4 or IPv6 address of the Route Reflector.
  • <AS_NUM> is the AS number to use for the network (set or determined above).

Setting up node-specific peering

If you are deploying a cluster of Route Reflectors, with each Calico node peering to a subset of Route Reflectors it will be necessary to set up the peerings on a node-by-node basis.

This would be the typical situation when scaling out to a very large size. For example, you may have:

  • a cluster of 100 route reflectors connected in a full mesh
  • a network of 100,000 Calico Docker nodes
  • each Calico Docker node is connected to two or three different Route Reflectors.

Configuring a node-specific Route Reflector peering

To configure a Route Reflector as a peer of a specific node, run the following from the node:

$ cat << EOF | calicoctl create -f -
apiVersion: v1
kind: bgpPeer
metadata:
  peerIP: <IP_RR>
  scope: node
  node: <NODENAME>
spec:
  asNumber: <AS_NUM>
EOF

Where:

  • <IP_RR> is the IPv4 or IPv6 address of the Route Reflector.
  • <AS_NUM> is the AS number to use for the network (set or determined above).
  • <NODENAME> is the name of the node.

Run this separately for each Route Reflector that you want to peer with the node.

Additional information

Example topology / multiple cluster IDs

When the topology includes a cluster of Route Reflectors, BGP uses the concept of a cluster ID to ensure there are no routing loops when distributing routes.

The Route Reflector image provided assumes that it has a fixed cluster ID for each Route Reflector rather than being configurable on a per peer basis. This simplifies the overall configuration of the network, but does place some limitations on the topology as described here.

The topology is based on the Top of Rack model where you would have a set of redundant route reflectors peering with all of the servers in the rack.

  • Each rack is assigned its own cluster ID (a unique number in IPv4 address format).
  • Each node (server in the rack) peers with a redundant set of route reflectors specific to that set rack.
  • All of the Route Reflectors across all racks form a full BGP mesh (this is handled automatically by the Calico BIRD Route Reflector image and does not require additional configuration).

Example scale topology

For example, to set up the topology described above, you would:

  • Spin up nodes N1 - N9
  • Spin up Route Reflectors RR1 - RR6
  • Add node specific peers, peering:
  • N1, N2 and N3 with RR1 and RR2
  • N4, N5 and N6 with RR3 and RR4
  • N7, N8 and N9 with RR5 and RR6
  • Add etcd config for the Route Reflectors:
  • RR1 and RR2 both using the cluster ID 1.0.0.1
  • RR2 and RR3 both using the cluster ID 1.0.0.2
  • RR4 and RR5 both using the cluster ID 1.0.0.3

Route Reflector with TLS/SSL Etcd

If you are running secure etcd, you will need to pass in additional options and set environment variables for the certificate and key files associated with your etcd instance.

When starting the Route Reflector container image, you need to mount the certificate files and environment variable filepaths for each file:

docker run -privileged -net=host -d                                \
           -e IP=<IPv4_RR>                                         \
           [-e IP6=<IPv6_RR>]                                      \
           -e ETCD_ENDPOINTS=<https://ETCD_IP:PORT>                \
           -v <FULL_PATH_TO_CERT_DIR>:<MOUNT_DIR>                  \
           -e ETCD_CA_CERT_FILE=<MOUNT_DIR>/<CA_FILE>              \
           -e ETCD_CERT_FILE=<MOUNT_DIR>/<CERT_FILE>               \
           -e ETCD_KEY_FILE=<MOUNT_DIR>/<KEY_FILE>                 \
           calico/routereflector:master

Where <FULL_PATH_TO_CERT_DIR> is a directory on the host that contains the certificate files (you can mount multiple directories with additional -v <DIR> parameters if they are in separate directories, but be sure to choose different <MOUNT_DIR> locations if this is the case).

You will also need to pass the certificate and key files as parameters in the curl statement when adding entries:

# IPv4 entries
curl --cacert <path_to_ca_cert> --cert <path_to_cert> --key <path_to_key> -L https://<ETCD_IP:PORT>:2379/v2/keys/calico/bgp/v1/rr_v4/<IPv4_RR> -XPUT -d value="{\"ip\":\"<IPv4_RR>\",\"cluster_id\":\"<CLUSTER_ID>\"}"
# IPv6 entries
curl --cacert <path_to_ca_cert> --cert <path_to_cert> --key <path_to_key> -L https://<ETCD_IP:PORT>:2379/v2/keys/calico/bgp/v1/rr_v6/<IPv6_RR> -XPUT -d value="{\"ip\":\"<IPv6_RR>\",\"cluster_id\":\"<CLUSTER_ID>\"}"