User guide

OpenFlow Agent Overview Web Services, CLI Scripting and OpenFlow
page 11-28 OmniSwitch AOS Release 7 Switch Management Guide March 2015
OpenFlow Agent Overview
OpenFlow is a communications interface defined between the control and forwarding layers that is used in
a Software Defined Network (SDN). OpenFlow essentially separates the control plane and the data plane
in the switch. Traditionally, switches and routers have made decisions on where packets should travel
based on rules local to the device. With OpenFlow, only the data plane exists on the switch itself, and all
control decisions are communicated to the switch from a central Controller. If the device receives a packet
for which it has no flow information, it sends the packet to the Controller for inspection, and the Control-
ler determines where that packet should be sent based on QoS-type rules configured by the user (drop the
packets to create a firewall, pass the packets to a specific port to perform load balancing, prioritize pack-
ets, etc).
The OmniSwitch can operate in AOS or OpenFlow mode, including a modified OpenFlow mode known as
Hybrid mode. AOS will designate the ports managed/controlled by AOS or by OpenFlow on a per-port
basis. By default, ports are managed/controlled by AOS.
The following are the key components available on an OmniSwitch for OpenFlow support.
OpenFlow Logical
An OpenFlow logical switch consists of a portion of the switch's resources that are managed by an Open-
Flow Controller (or set of Controllers) via the OpenFlow Agent. Logical switches can be configured on an
OmniSwitch, with each logical switch supporting separate controllers. A logical switch has a VLAN,
physical ports, and/or link aggregate ports assigned to it. All packets received on these ports are forwarded
directly to the Openflow agent. Spanning tree and source learning do not operate on OpenFlow assigned
ports.
OpenFlow Normal Mode
In Normal mode, the logical switch operates as per the OpenFlow standards.
OpenFlow Hybrid (API) Mode
In Hybrid mode, the logical switch acts as an interface through which the Controller may insert flows.
These flows are treated as QoS policy entries and offer the same functionality. A Hybrid logical switch
operates on all ports, link aggregates, and VLANs not assigned to other OpenFlow logical switches.
Support OpenFlow Parameters
In following OpenFlow tables, match fields, groups and actions are supported.
Flow Definitions:
• Exact Match
• Wildcard
• MAC Table
Match Fields:
• Ingress Port
• Ethernet Destination Address