一）基本要求
1.拓扑文件
2.wireshark抓包
Hello
控制器6633端口（我最高能支持OpenFlow 1.0） ---> 交换机33372端口(由于我当时将窗口关闭了，再次运行时交换机端口号发生变化，这张图是关闭窗口后的)
交换机33372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
·Features Request
控制器6633端口（我需要你的特征信息） ---> 交换机33372端口
·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33372端口
·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。
``
·Features Reply
交换机33372端口（这是我的特征信息，请查收） ---> 控制器6633端口
·Packet_in
交换机33372端口（有数据包进来，请指示）--- 控制器6633端口
·Flow_mod
分析抓取的flow_mod数据包，控制器通过6633端口向交换机33372端口下发流表项，指导数据的转发处理
·Packet_out
控制器6633端口（请按照我给你的action进行处理） ---> 交换机33372端口
3.交互图
（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。
·Hello
/* 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;
};
·Features Request
/* 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;
};
·Set Conig
/* 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. */
};
·Port Staus
/* 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
/* 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. */
};
·Packet_in
1.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. */
};
2.有匹配条目,对应的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. */
};
·Flow_mod
/* Fields to match against flows */
struct ofp_match {
uint32_t wildcards; /* Wildcard fields. */
uint16_t in_port; /* Input switch port. */
uint8_t dl_src[OFP_ETH_ALEN]; /* Ethernet source address. */
uint8_t dl_dst[OFP_ETH_ALEN]; /* Ethernet destination address. */
uint16_t dl_vlan; /* Input VLAN id. */
uint8_t dl_vlan_pcp; /* Input VLAN priority. */
uint8_t pad1[1]; /* Align to 64-bits */
uint16_t dl_type; /* Ethernet frame type. */
uint8_t nw_tos; /* IP ToS (actually DSCP field, 6 bits). */
uint8_t nw_proto; /* IP protocol or lower 8 bits of
* ARP opcode. */
uint8_t pad2[2]; /* Align to 64-bits */
uint32_t nw_src; /* IP source address. */
uint32_t nw_dst; /* IP destination address. */
uint16_t tp_src; /* TCP/UDP source port. */
uint16_t tp_dst; /* TCP/UDP destination port. */
};
/* 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. */
};
·Packet_out
/* Action header that is common to all actions. The length includes the
* header and any padding used to make the action 64-bit aligned.
* NB: The length of an action *must* always be a multiple of eight. */
struct ofp_action_header {
uint16_t type; /* One of OFPAT_*. */
uint16_t len; /* Length of action, including this
header. This is the length of action,
including any padding to make it
64-bit aligned. */
uint8_t pad[4];
};
OFP_ASSERT(sizeof(struct ofp_action_header) == 8);
/* 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.) */
};
个人总结
1.查看Hello数据包时要先抓包再建立拓扑
2.Flow_mod的数据包在pingall之后才会出现被wireshark工具捕捉到
3.发现找不到Features Request的源码，对比抓包信息后，发现和hello的格式一模一样,所以源码是一样的
4.了解了OpenFlow协议中交换机与控制器的消息交互过程，了解了wireshark 抓包后的信息大概表示什么内容
5.通过本次实验，学会了如何运用 wireshark 对 OpenFlow 协议数据交互过程进行抓包；以及借助包解析工具，分析与解释 OpenFlow协议的数据包交互过程与机制。总的来说实验难度不大，太多数据包交互，密密麻麻的看的头晕。