1. Switch Components

交换机类型：

OpenFlow-only： 只支持OpenFlow操作

OpenFlow-hybrid： 支持OpenFlow操作和传统以太网交换操作（传统2层以太网包交换，VLAN隔离， 3层IPv4和IPv6路由, ACL, QoS)

OpenFlow Ports

ingress port: 收包

egress port： 发包

Standard ports: 物理端口，逻辑端口或局部保留端口

流表

• match fields: to match against packets. These consist of the ingress port and packet headers, and optionally other pipeline fields such as metadata specified by a previous table.

• priority: matching precedence of the flow entry.

• counters: updated when packets are matched.

• instructions: to modify the action set or pipeline processing.

• timeouts: maximum amount of time or idle time before flow is expired by the switch.

• cookie: opaque data value chosen by the controller. May be used by the controller to filter flow entries affected by flow statistics, flow modification and flow deletion requests. Not used when processing packets.

• flags: flags alter the way flow entries are managed, for example the flag OFPFF_SEND_FLOW_REM triggers flow removed messages for that flow entry.

2. Packet Flow