- 拓扑文件
- 抓包流程图
1、hello
55394向6633发送hello包，并且使用openflow1.0
6633向55394发送hello包，并且使用openflow1.0
2、features_request
控制器6633端口（我需要你的特征信息） ---> 交换机55394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55394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55394端口（这是我的特征信息，请查收） ---> 控制器6633端口
6、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是OUTPUT=CONTROLLER时，交换机35534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34286端口、交换机34286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（请按照我给你的action进行处理） ---> 交换机55394端口
9、交互图
- 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？
答：交换机和控制器建立通信时是使用TCP协议 - 进阶作业
1、Hello
struct ofp_header {
uint8_t version; /* 版本号OFP_VERSION. */
uint8_t type; /* 消息类型One of the OFPT_ constants. */
uint16_t length; /* 长度Length including this ofp_header. */
uint32_t xid; /* ID 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
struct ofp_header {
uint8_t version; /* 版本号OFP_VERSION. */
uint8_t type; /* 消息类型One of the OFPT_ constants. */
uint16_t length; /* 长度Length including this ofp_header. */
uint32_t xid; /* ID Transaction id associated with this packet.
Replies use the same id as was in the request
to facilitate pairing. */
};
3、Set Config
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
};//不同flag代表不同的处理方式
/* Switch configuration. */
struct ofp_switch_config {
struct ofp_header header;
uint16_t flags; /*用来指示交换机如何处理 IP 分片数据包 OFPC_* flags. */
uint16_t miss_send_len; /* 用来指示当一个交换机无法处理的数据包到达时，将数据包发给控制器的最大字节数。Max bytes of new flow that datapath should
send to the controller. */
};
OFP_ASSERT(sizeof(struct ofp_switch_config) == 12);
4、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;
};
OFP_ASSERT(sizeof(struct ofp_port_status) == 64);
//这个是当交换机端口发生变化时，告知控制器相应的端口状态,发生变化包括增加、删除、修改物理端口，则需发送port status来告知
5、Features Reply
/* Switch features. */
struct ofp_switch_features {
struct ofp_header header;
uint64_t datapath_id; /* 唯一标识ID号Datapath unique ID. The lower 48-bits are for
a MAC address, while the upper 16-bits are
implementer-defined. */
uint32_t n_buffers; /*缓冲区可缓存的最大数据包个数 Max packets buffered at once. */
uint8_t n_tables; /* 流表数量Number of tables supported by datapath. */
uint8_t pad[3]; /* Align to 64-bits. */
/* Features. */
uint32_t capabilities; /*支持的特殊功能Bitmap of support "ofp_capabilities". */
uint32_t actions; /* 支持的动作 Bitmap of supported "ofp_action_type"s. */
/* Port info.*/
struct ofp_phy_port ports[0]; /*物理端口描述列表 Port definitions. The number of ports
is inferred from the length field in
the header. */
};
OFP_ASSERT(sizeof(struct ofp_switch_features) == 32);
6、Packet_in
/* Packet received on port (datapath -> controller). */
struct ofp_packet_in {
struct ofp_header header;
uint32_t buffer_id; /*Packet-in消息所携带的数据包在交换机缓存区中的ID ID assigned by datapath. */
uint16_t total_len; /* data字段的长度Full length of frame. */
uint16_t in_port; /* 数据包进入交换机时的端口号Port on which frame was received. */
uint8_t reason; /*发送Packet-in消息的原因 Reason packet is being sent (one of OFPR_*) */
uint8_t pad;
uint8_t data[0]; /*携带的数据包 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);
7、Flow_mod
/* Flow setup and teardown (controller -> datapath). */
struct ofp_flow_mod {
struct ofp_header header;
struct ofp_match match; /* 流表的匹配域 Fields to match */
uint64_t cookie; /*流表项标识符 Opaque controller-issued identifier. */
/* Flow actions. */
uint16_t command; /* 可以是ADD,DELETE,DELETE-STRICT,MODIFY,MODIFY-STRICTOne of OFPFC_*. */
uint16_t idle_timeout; /*空闲超时时间 Idle time before discarding (seconds). */
uint16_t hard_timeout; /* 最大生存时间 Max time before discarding (seconds). */
uint16_t priority; /*优先级，优先级高的流表项优先匹配 Priority level of flow entry. */
uint32_t buffer_id; /*缓存区ID ,用于指定缓存区中的一个数据包按这个消息的action列表处理 Buffered packet to apply to (or -1).
Not meaningful for OFPFC_DELETE*. */
uint16_t out_port; /*如果这条消息是用于删除流表则需要提供额外的匹配参数 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; /*标志位，可以用来指示流表删除后是否发送flow‐removed消息，添加流表时是否检查流表重复项，添加的流表项是否为应急流表项。 One of OFPFF_*. */
struct ofp_action_header actions[0]; /* action列表The action length is inferred
from the length field in the
header. */
};
OFP_ASSERT(sizeof(struct ofp_flow_mod) == 72);
8、Packet_out
/* Send packet (controller -> datapath). */
struct ofp_packet_out {
struct ofp_header header;
uint32_t buffer_id; /*交换机缓存区id，如果为-1则指定的为packet-out消息携带的data字段 ID assigned by datapath (-1 if none). */
uint16_t in_port; /* 如果buffer_id为‐1，并且action列表中指定了Output=TABLE的动作,in_port将作为data段数据包的额外匹配信息进行流表查询Packet's
input port (OFPP_NONE if none). */
uint16_t actions_len; /*action列表的长度，可以用来区分actions和data段 Size of action array in bytes. */
struct ofp_action_header actions[0]; /*动作列表 Actions. */
/* uint8_t data[0]; */ /*数据缓存区，可以存储一个以太网帧，可选 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
本次实验主要是学会了能够运用 wireshark 对 OpenFlow 协议数据交互过程进行抓包，用抓包软件获取控制器与交换机之间的通信数据包。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。进阶实验主要是对源代码进行分析，这个花费了较多时间去了解，在实验过程中遇到的问题，通过询问同学以及查找资料也学习到了很多知识，并且本次实验让我对wireshark抓包的使用更加的熟练。