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Components and Ports of OpenFlow Protocol
OpenFlow Switch Components.
An OpenFlow consists of:
§ Flow table(s)
§ Groups Table
§ OpenFlow Secure channel.
A flow table in an OpenFlow switch consists of a sets of flow table entries which contain multiple information such as match fields, counters and a sets of instructions to be applied for matching packets.
There might be multiple flow tables existing in an OpenFlow switch and the flow tables will be handled through pipeline processing. For example, when a packet is forwarded and matched with the flow entry in the first flow table, the corresponding instruction will be associated with pipeline processing instruction which allows packets to be sent to subsequent tables for further processing.
The table pipeline processing stops if the instructions associated with a matching flow entry does not specify the following flow table.
The group table contain a list of group entries and each group entry is associated with
action buckets or action groups; Packets defined in group and matched with the group
entries will be matched with one or more action buckets.
The secure channel is the component used to connect to external controller and
establishes communication channel through OpenFlow protocol.
OpenFlow Ports
§ An OpenFlow switch must be able to support 3 types of OpenFlow standards:
Ø OpenFlow ports are used to connect an OpenFlow switch to another OpenFlow switch and also connect to external network.
ØOpenFlow switch connect to each other logically via OpenFlow ports. OpenFlow packets are received from the ingress port and the packet be processed and matched through pipeline processing and may be forwarded out to an Output port.
ØThe OpenFlow reserved ports are also considered as OpenFlow specification defined ports, used to specify forwarding actions once a flow entry is matched.
The compulsory required reserved ports are listed below:
ALL: Represents every port on switch can be used to forward packet and work as
output ports.
CONTROLLER: Represents the port used for communication channel between
switch and controller; it can work as a ingress or output port.
TABLE: Represents the start of the OpenFlow pipeline processing, to submit the
received packets to the first flow table for pipeline processing; it can work as a
output port.
IN_PORT: Represents the packet ingress port and work as output port to forward
packets out from the ingress port where it receives the packet.
ANY: A special port where no handling action will be done; it can neither be an
ingress or output port.
Click Here The History of Architecture of OpenFlow Protocol to the BACKWARD post
Click Here Description and Matching of the OpenFlow Table to the NEXT post <COMING SOON>
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