Connectivity Guide

OpenFlow use cases
OS10 OpenFlow protocol support allows the exibility of using vendor-neutral applications and to use applications that you create. For
example, the OS10 OpenFlow implementation supports L2 applications similar to the ones found in the following websites:
• https://github.com/osrg/ryu/tree/master/ryu/app (only L2 applications are supported)
• https://github.com/osrg/ryu/tree/master/ryu/app
NOTE: OS10 supports applications based on OpenFlow versions 1.0 and 1.3.
• Switching loop removal
Consider the case of a single broadcast domain where switching loops are common. This issue occurs because of redundant paths in an
L2 network.
Switching loops create broadcast storms with broadcasts and multicasts being forwarded out of every switch port. Every switch in the
network repeatedly re-broadcasts the messages and oods the entire network.
To solve broadcast storms in an OpenFlow network, a centralized controller makes all the control plane decisions and manages the
switches. The controller has the complete view of the topology. MAC address learning is centralized. OpenFlow identies the correct
path and forwards the packets to the relevant switch thereby avoiding switching loops.
• Reactive ow installation
Consider the case of dynamic learning of ows for bidirectional trac. Flows are learnt as and when a packet arrives.
With dynamic learning in an OpenFlow network, the OpenFlow switch receives a packet that does not match the ow table entries and
sends the packet to the SDN controller to process it. The controller identies the path the packet has to traverse and updates the ow
table with a new entry. The controller also decides the caching time of the ow table entries.
Congure OpenFlow
Ensure IP connectivity between the switch and the controller. When you convert the switch from Normal mode to OpenFlow mode, the
switch retains the management, interface, and AAA settings.
The following example lists the minimum conguration needed to establish the connection between the OpenFlow controller and a logical
switch instance.
1 Enter the OPENFLOW conguration mode.
OS10# configure terminal
OS10 (config)# openflow
OS10 (config-openflow)#
2 Enable the OpenFlow-only mode.
OS10 (config-openflow)# mode openflow-only
The system prompts you to reload the switch. Enter yes to enable OpenFlow-only mode.
NOTE
: When the switch starts up in OpenFlow mode, it disables all L2 and 3 protocols. Many CLI commands are not
available when the switch is in OpenFlow-only mode. For a list of commands that are available in OpenFlow-only mode,
see CLI commands available in the OpenFlow-only mode.
3 Congure a logical switch instance.
a Option 1; for OOB management:
1 Congure an IP address for the management port. Ensure that there is IP connectivity between the switch and the
controller.
OS10# configure terminal
OS10 (config)# interface management 1/1/1
OS10 (conf-if-ma-1/1/1)# ip address 11.1.1.1/24
OS10 (conf-if-ma-1/1/1)# no shutdown
OS10 (conf-if-ma-1/1/1)# exit
678
OpenFlow