实验3:OpenFlow协议分析实践

1)hello
控制器6633端口(最高支持OpenFlow 1.0)-->交换机50822端口

交换机50822端口(最高支持OpenFlow 1.5)-->控制器6633端口

2)Feature Request
控制器6633端口(需要你的特征信息)-->交换机50836端口

3)set conig
控制器52298端口(请按照我给你的flag和max bytes of packet进行配置)-->控制器52298端口

3)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
4)Features Reply

5)Packet_in
有两种情况:
·交换机查找流表,发现没有匹配条目时
·有匹配条目但是对应的action口是OUTPUT=CONTROLLER时
交换机50882端口(有数据包进来,请指示)-->控制器6633端口

6)Flow_mod
分析抓取的flow_mod数据包,控制器通过6633端口向交换机50822端口,交换机50836端口下发流表项,指导数据的转发处理


7)Packet_out
控制器6633端口(请按照我给你的action进行处理)-->交换机552298duankou

·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

答:是TCP协议

3.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。
1)Hello

点击查看代码
/* Header on all OpenFlow packets. */
struct ofp_header {
    uint8_t version;    /* OFP_VERSION. */
    uint8_t type;       /* One of the OFPT_ constants. */
    uint16_t length;    /* Length including this ofp_header. */
    uint32_t xid;       /* Transaction id associated with this packet.
                           Replies use the same id as was in the request
                           to facilitate pairing. */
};
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;
};


2)Features Request

点击查看代码
/* Header on all OpenFlow packets. */
struct ofp_header {
    uint8_t version;    /* OFP_VERSION. */
    uint8_t type;       /* One of the OFPT_ constants. */
    uint16_t length;    /* Length including this ofp_header. */
    uint32_t xid;       /* Transaction id associated with this packet.
                           Replies use the same id as was in the request
                           to facilitate pairing. */
};
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;
};

3)Set Conig

点击查看代码
/* 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. */
};

4)Port Staus

点击查看代码
/* 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);

5)Features Reply
点击查看代码
/* Description of a physical port */
struct ofp_phy_port {
    uint16_t port_no;
    uint8_t hw_addr[OFP_ETH_ALEN];
    char name[OFP_MAX_PORT_NAME_LEN]; /* Null-terminated */

    uint32_t config;        /* Bitmap of OFPPC_* flags. */
    uint32_t state;         /* Bitmap of OFPPS_* flags. */

    /* Bitmaps of OFPPF_* that describe features.  All bits zeroed if
     * unsupported or unavailable. */
    uint32_t curr;          /* Current features. */
    uint32_t advertised;    /* Features being advertised by the port. */
    uint32_t supported;     /* Features supported by the port. */
    uint32_t peer;          /* Features advertised by peer. */
};
OFP_ASSERT(sizeof(struct ofp_phy_port) == 48);

/* 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. */
};

6)Packet_in

点击查看代码
·交换机查找流表,没有匹配条目
/* 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. */
};
·交换机查找流表,有匹配条目,对应action是OUTPUT=CONTROLLER,固定收到向控制器发送包
/* 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. */
};

7)Flow_mod
点击查看代码
/* 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. */
};

8)Packet_out
点击查看代码
/* 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);

个人总结:本次实验的难易程度适中,主要是运用抓包软件Wireshark来进一步增强对构建拓扑以及控制器之间是怎么交互运行的,对 OpenFlow 协议数据交互过程进行抓包和wireshark的一些基础功能的运用,通过本次实验对SDN学习的内容的方向有了一定的了解,和SDN对交换机的优化和实现有了基础的认识。通过本次实验,我对抓包软件Wireshark更加的了解以及可以熟练掌握,对openflow协议数据交互过程有了进一步的了解和认识,对SDN也有了一些了解,同时也可以借助工具对OpenFlow协议数据交互过程进行分析,同时需要注意的店的点是,需要先打开抓包软件Wireshark,再进行建立拓扑

posted @ 2022-10-03 17:17  212002125王昊  阅读(8)  评论(0编辑  收藏  举报