Understanding Fabric Status Updates, vPorts and Keepalives

Instead of transactions, which are reserved for create, delete, modify, add or remove commands, NetVisor OS uses status update messages to distribute information across the fabric.

Unlike transactions, NetVisor OS does not strictly guarantee the status update data to be synchronized across the fabric. 

NetVisor OS sends the following states from the local node to the other nodes in the fabric:

  • Node State
  • Port State
  • VLAN State
  • Owned vPort State
  • Layer 3 Entry State

NetVisor OS uses vPort (or virtual port) as Layer 2 entries managed by the software and associated to ports where a node performs MAC address learning. vPorts contain information such as the MAC and IP address of a host, the VLAN and the connected port, the state, and other parameters.

In a fabric a node only sends status updates for vPorts that “is part of the fabric, which means that it sends updates only for the states of the hosts directly connected to that node. NetVisor OS uses the term 'owned vPorts' to represent directly connected hosts.

You can display this information about directly connected hosts using the command, vport-show

For example:

CLI (network-admin@switch) > vport-show

mac                        vlan        ip                ports        state        migrate

-----------------        ----        --------        -----        -----        ------

00:00:4c:06:91:f8        514        61        active          9


In addition, NetVisor OS sends status updates whenever a state changes on the fabric. For example, if a port goes down, or you create a new VLAN, the node with the port or VLAN sends a status update about the specific change.

If sending the update message fails, NetVisor OS attempts to resend it every 250ms.

With multiple nodes configured in the same fabric instance, switches send out special messages, called fabric keepalives, typically every 10 seconds to allow fabric peers to keep track of the online state of other nodes in the same fabric instance.

If a fabric keep-alive message is not received from a specific node for a period of time (30 s) equal to 3 times the transmission interval (10 s), the suddenly-gone-silent node’s state is marked as offline by its neighbors. This inter-device connectivity/status check is performed with every other node within the same fabric instance.