Users 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
When you convert the switch from Normal mode to OpenFlow mode, the switch retains the management, interface, and AAA settings.
NOTE
: Ensure IP connectivity between the switch and the controller.
The following lists the minimum conguration you need to establish a 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
Reload the switch. Enter yes to enable OpenFlow-only mode.
NOTE
: When the switch starts up in OpenFlow mode, it disables all Layer 2 (L2) and Layer 3 (L3) protocols. Many CLI
commands are not available in OpenFlow-only mode. For a list of available commands in OpenFlow-only mode, see
OpenFlow-only mode commands.
3 Congure a logical switch instance.
a Option 1; for Out of Band (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
1020
OpenFlow