一实验目的
1、能够运用 wireshark 对 OpenFlow 协议数据交互过程进行抓包；
2、能够借助包解析工具，分析与解释 OpenFlow协议的数据包交互过程与机制。
二、实验环境
Ubuntu 20.04 Desktop amd64
三、实验要求
（一）基本要求
1、搭建下图所示拓扑，完成相关 IP配置，并实现主机与主机之间的 IP 通信。用抓包软件获取控制器与交换机之间的通信数据。 
2.查看抓包结果，分析OpenFlow协议中交换机与控制器的消息交互过程，画出相关交互图或流程图。
HELLO（控制器6633端口 ---> 交换机48996端口）
1.HELLO（交换机6633端口（我最高能支持OpenFlow 1.0） ---> 控制器48996端口）
2.Features Request（控制器6633端口（我需要你的特征信息） ---> 交换机48982端口）
3.Set Conig（控制器6633端口（请按照我给你的flag和max bytes of packet进行配置） ---> 交换机48982端口）
4.Port_Status（当交换机端口发生变化时，告知控制器相应的端口状态)
5.Features Reply(交换机48982端口（这是我的特征信息，请查收） ---> 控制器6633端口)
6.Packet_in
交换机48982端口（有数据包进来，请指示）--- 控制器6633端口
.
7.Flow_mod控制器通过6633端口向交换机48996端口、交换机44214端口下发流表项，指导数据的转发处理
8.Packet_out控制器6633端口向交换机48982端口发送数据，并告知交换机输出到65531端口。
查看抓包结果，分析OpenFlow协议中交换机与控制器的消息交互过程，画出相关交互图或流程图
回答问题：交换机与控制器建立通信时是使用TCP协议还是UDP协议？
TCP
(二）进阶要求
将抓包基础要求第2步的抓包结果对照OpenFlow源码，了解OpenFlow主要消息类型对应的数据结构定义
OpenFlow主要消息类型
enum ofp_type {
/* Immutable messages. */
OFPT_HELLO, /* Symmetric message */
OFPT_ERROR, /* Symmetric message */
OFPT_ECHO_REQUEST, /* Symmetric message */
OFPT_ECHO_REPLY, /* Symmetric message */
OFPT_VENDOR, /* Symmetric message */
/* Switch configuration messages. */
OFPT_FEATURES_REQUEST, /* Controller/switch message */
OFPT_FEATURES_REPLY, /* Controller/switch message */
OFPT_GET_CONFIG_REQUEST, /* Controller/switch message */
OFPT_GET_CONFIG_REPLY, /* Controller/switch message */
OFPT_SET_CONFIG, /* Controller/switch message */
/* Asynchronous messages. */
OFPT_PACKET_IN, /* Async message */
OFPT_FLOW_REMOVED, /* Async message */
OFPT_PORT_STATUS, /* Async message */
/* Controller command messages. */
OFPT_PACKET_OUT, /* Controller/switch message */
OFPT_FLOW_MOD, /* Controller/switch message */
OFPT_PORT_MOD, /* Controller/switch message */
/* Statistics messages. */
OFPT_STATS_REQUEST, /* Controller/switch message */
OFPT_STATS_REPLY, /* Controller/switch message */
/* Barrier messages. */
OFPT_BARRIER_REQUEST, /* Controller/switch message */
OFPT_BARRIER_REPLY, /* Controller/switch message */
/* Queue Configuration messages. */
OFPT_QUEUE_GET_CONFIG_REQUEST, /* Controller/switch message */
OFPT_QUEUE_GET_CONFIG_REPLY /* Controller/switch message */
};
Hello
/* OFPT_HELLO. This message has an empty body, but implementations must
* ignore any data included in the body, to allow for future extensions. */
struct ofp_hello {
struct ofp_header header;
};
features request源码参数格式与HELLO的一致
features reply
/* Switch features. */
struct ofp_switch_features {
struct ofp_header header;
uint64_t datapath_id; /* Datapath unique ID. The lower 48-bits are for
a MAC address, while the upper 16-bits are
implementer-defined. */
uint32_t n_buffers; /* Max packets buffered at once. */
uint8_t n_tables; /* Number of tables supported by datapath. */
uint8_t pad[3]; /* Align to 64-bits. */
/* Features. */
uint32_t capabilities; /* Bitmap of support "ofp_capabilities". */
uint32_t actions; /* Bitmap of supported "ofp_action_type"s. */
/* Port info.*/
struct ofp_phy_port ports[0]; /* Port definitions. The number of ports
is inferred from the length field in
the header. */
};
port_status
/* A physical port has changed in the datapath */
struct ofp_port_status {
struct ofp_header header;
uint8_t reason; /* One of OFPPR_*. */
uint8_t pad[7]; /* Align to 64-bits. */
struct ofp_phy_port desc;
};
set_config
/* Switch configuration. */
struct ofp_switch_config {
struct ofp_header header;
uint16_t flags; /* OFPC_* flags. */
uint16_t miss_send_len; /* Max bytes of new flow that datapath should
send to the controller. */
};
packet_in
/* Packet received on port (datapath -> controller). */
struct ofp_packet_in {
struct ofp_header header;
uint32_t buffer_id; /* ID assigned by datapath. */
uint16_t total_len; /* Full length of frame. */
uint16_t in_port; /* Port on which frame was received. */
uint8_t reason; /* Reason packet is being sent (one of OFPR_*) */
uint8_t pad;
uint8_t data[0]; /* Ethernet frame, halfway through 32-bit word,
so the IP header is 32-bit aligned. The
amount of data is inferred from the length
field in the header. Because of padding,
offsetof(struct ofp_packet_in, data) ==
sizeof(struct ofp_packet_in) - 2. */
};
OFP_ASSERT(sizeof(struct ofp_packet_in) == 20);
packet_out
/* Send packet (controller -> datapath). */
struct ofp_packet_out {
struct ofp_header header;
uint32_t buffer_id; /* ID assigned by datapath (-1 if none). */
uint16_t in_port; /* Packet's input port (OFPP_NONE if none). */
uint16_t actions_len; /* Size of action array in bytes. */
struct ofp_action_header actions[0]; /* Actions. */
/* uint8_t data[0]; */ /* Packet data. The length is inferred
from the length field in the header.
(Only meaningful if buffer_id == -1.) */
};
OFP_ASSERT(sizeof(struct ofp_packet_out) == 16);
flow_mod
/* Flow setup and teardown (controller -> datapath). */
struct ofp_flow_mod {
struct ofp_header header;
struct ofp_match match; /* Fields to match */
uint64_t cookie; /* Opaque controller-issued identifier. */
/* Flow actions. */
uint16_t command; /* One of OFPFC_*. */
uint16_t idle_timeout; /* Idle time before discarding (seconds). */
uint16_t hard_timeout; /* Max time before discarding (seconds). */
uint16_t priority; /* Priority level of flow entry. */
uint32_t buffer_id; /* Buffered packet to apply to (or -1).
Not meaningful for OFPFC_DELETE*. */
uint16_t out_port; /* For OFPFC_DELETE* commands, require
matching entries to include this as an
output port. A value of OFPP_NONE
indicates no restriction. */
uint16_t flags; /* One of OFPFF_*. */
struct ofp_action_header actions[0]; /* The action length is inferred
from the length field in the
header. */
};
OFP_ASSERT(sizeof(struct ofp_flow_mod) == 72);
三、总结
本次实验与上次实验相比，一个是先pingall再抓包，另一个是先抓包再pingall，在熟悉上次实验的过程之后实验做起来会比较容易。
标签：OFPT,struct,OpenFlow,端口,实践,header,ofp,实验,message From： https://www.cnblogs.com/123456aabbssdd/p/16756861.html