1.基础要求只需要提交导入到/home/用户名/学号/lab3/目录下的拓扑文件，wireshark抓包的结果截图和对应的文字说明；
a)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
控制器6633端口（我最高能支持OpenFlow 1.0） ---> 交换机39928端口
交换机39928端口（我最高能支持OpenFlow 1.5） ---> 控制器6633端口
于是双方建立连接，并使用OpenFlow 1.0
控制器6633端口（我需要你的特征信息） ---> 交换机39928端口
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39928端口
交换机39928端口（这是我的特征信息，请查收） ---> 控制器6633端口
交换机39928端口（有数据包进来，请指示）--- 控制器6633端口
控制器通过6633端口向交换机39928端口下发流表项，指导数据的转发处理
控制器6633端口（请按照我给你的action进行处理） ---> 交换机39928端口
b)画出相关交互图或流程图。
c)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？
交换机与控制器建立通信时是使用TCP协议
2.进阶要求为选做，有完成的同学请提交相关截图对应的OpenFlow代码，加以注释说明，有完成比未完成的上机分数更高。
HELLO包：
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struct ofp_header {
uint8_t version; /* OFP_VERSION. */--协议版本号
uint8_t type; /* One of the OFPT_ constants. */--包类型
uint16_t length; /* Length including this ofp_header. */--报文长度
uint32_t xid; /* Transaction id associated with this packet.
Replies use the same id as was in the request
to facilitate pairing. */--与此包关联的事务id
};
</details>
OFP_ASSERT(sizeof(struct ofp_header) == 8);
/* 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：
点击查看代码
struct ofp_header {
uint8_t version; /* OFP_VERSION. */--协议版本号
uint8_t type; /* One of the OFPT_ constants. */--包类型
uint16_t length; /* Length including this ofp_header. */--报文长度
uint32_t xid; /* Transaction id associated with this packet.
Replies use the same id as was in the request
to facilitate pairing. */--与此包关联的事务id
};
</details>
OFP_ASSERT(sizeof(struct ofp_header) == 8);
/* 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;
};
Set Conig:
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enum ofp_config_flags {
/* Handling of IP fragments. */
OFPC_FRAG_NORMAL = 0, /* No special handling for fragments. */
OFPC_FRAG_DROP = 1, /* Drop fragments. */
OFPC_FRAG_REASM = 2, /* Reassemble (only if OFPC_IP_REASM set). */
OFPC_FRAG_MASK = 3
};
/* Switch configuration. */
struct ofp_switch_config {
struct ofp_header header;
uint16_t flags; /* OFPC_* flags. */--flag：指示交换机如何处理 IP分片数据包，不同flags值处理方式不同
uint16_t miss_send_len; /* Max bytes of new flow that datapath should
send to the controller. */--数据路径应该发送给控制器的新流的最大字节数
};
OFP_ASSERT(sizeof(struct ofp_switch_config) == 12);
Port_Status：
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/* What changed about the physical port */
enum ofp_port_reason {
OFPPR_ADD, /* The port was added. */
OFPPR_DELETE, /* The port was removed. */
OFPPR_MODIFY /* Some attribute of the port has changed. */
};
/* 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;
};
OFP_ASSERT(sizeof(struct ofp_port_status) == 64);
Features Reply：
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/* 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. */--标识id
uint32_t n_buffers; /* Max packets buffered at once. */--一次缓冲的最大数据包数。
uint8_t n_tables; /* Number of tables supported by datapath. */--数据路径支持的表数。
uint8_t pad[3]; /* Align to 64-bits. */
/* Features. */
uint32_t capabilities; /* Bitmap of support "ofp_capabilities". */--支持的特殊功能
uint32_t actions; /* Bitmap of supported "ofp_action_type"s. */--支持的动作
/* Port info.*/
struct ofp_phy_port ports[0]; /* Port definitions. The number of ports
is inferred from the length field in
the header. */
};
OFP_ASSERT(sizeof(struct ofp_switch_features) == 32);
Packet_in：
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/* Why is this packet being sent to the controller? */
enum ofp_packet_in_reason {
OFPR_NO_MATCH, /* No matching flow. */
OFPR_ACTION /* Action explicitly output to controller. */
};
/* 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);
Flow_mod：
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enum ofp_flow_mod_flags {
OFPFF_SEND_FLOW_REM = 1 << 0, /* Send flow removed message when flow
* expires or is deleted. */
OFPFF_CHECK_OVERLAP = 1 << 1, /* Check for overlapping entries first. */
OFPFF_EMERG = 1 << 2 /* Remark this is for emergency. */
};
/* 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);
Packet_out：
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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);