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。
控制器6633端口（我最高能支持OpenFlow 1.0） ---> 交换机58076端口
交换机58076端口（我最高能支持OpenFlow 1.3） ---> 控制器6633端口
控制器6633端口（我需要你的特征信息） ---> 交换机58076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58076端口
交换机58076端口（这是我的特征信息，请查收） ---> 控制器6633端口
- 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58076端口（有数据包进来，请指示）--- 控制器6633端口
分析抓取的flow_mod数据包，控制器通过6633端口向交换机58076端口、交换机58076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35534端口
交互图
进阶要求
1.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. */
};
2.Features Request与hello代码段一致
3.OFPT_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. */
};
4.FEATURES_REPLAY
python ```
/* 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. */
};
/* 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. */
};
### 5.PACKET_IN
``` python
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. */
};
6.PACKET_OUT
··· python
/* 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.) */
};
### 7.FLOW_MOD
``` python
/* 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. */
};
个人总结
关于难度
- 本次实验难度简单。基本以阅读为主，没有什么操作，属于认知性实验。通过这次实验了解并掌握了OpenFlow通讯过程中数据包的流动过程，了解了Openflow通讯过程中都存在哪些包，及其作用。
实验中遇到的问题：
- 开wireshark后创建拓扑，过滤Openflow数据包，并没有发现Flow_Mod数据包，通过了解这个包是指导数据的转发处理，通过命令行pingall就出现了这个包
- 问题2：开始在过滤后发现找不到58076给6633端口的hello报文 解决方案：取消过滤后找到了，我认为是以为他是open flow vesion 1.5导致的，使得我在openflow_v1找不到
实验收获：
- 这次实验学会用过滤器输入“OpenFlow_v1和Openflow_v6”等进行数据包过滤，运用 wireshark 对 OpenFlow 协议数据交互过程进行抓包；
- 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，将抓包结果对照OpenFlow源码，了解到OpenFlow主要消息类型对应的数据结构定义。