Autonomous System Number (ASN)¶
In the routing fabric of a data centre, a MOSK cluster with OpenSDN enabled can be represented either by a separate Autonomous System (AS) or as part of a bigger autonomous system. In either case, OpenSDN needs to participate in the BGP peering, exchanging routes with external devices and within the cloud.
The OpenSDN Kubernetes Controller acts as an internal (iBGP) route reflector
for the cloud AS by populating /32 routes pointing to VMs across all
compute nodes as well as the cloud’s edge gateway devices in case they belong
to the same AS. Apart from being an iBGP router reflector for the cloud AS, the
OpenSDN Kubernetes Controller can act as a BGP peer for autonomous systems
external to the cloud, for example, for the AS configured across the
leaf-spine fabric of the data center.
The Autonomous System Number (ASN) setting contains the unique identifier of the autonomous system that the MOSK cluster with OpenSDN belongs to. The ASN number does not affect the internal iBGP communication between vRouters running on the compute nodes. Such communication will work regardless of the ASN number settings. However, any network appliance that is not managed by the OpenSDN control plane will have BGP configured manually. Therefore, the ASN settings should be configured accordingly on both sides. Otherwise, it would result in the inability to establish BPG sessions, regardless of whether the external device peers with OpenSDN over iBGP or eBGP.
Configuring ASNs¶
The TFOperator custom resource enables you to define ASN settings for
your OpenSDN cluster.
Important
The TFOperator custom resource must be the only place to configure
the cluster ASN. Performing these configurations through the OpenSDN
web UI, CLI, or API does not provide the configuration persistency,
and the settings defined this way may get reset to defaults during
the cluster services restart or update.
Note
Defining the default values for ASN parameters in the TFOperator custom resource is unnecessary.
Parameter |
Default value |
Description |
|---|---|---|
|
|
Defines ASN of the control node. |
|
|
Enables the 4-byte ASN format. |
Example configuration:
features:
config:
bgpAsn: 64515
enable4ByteAS: true