1. 利用Mininet仿真平台构建如下图所示的网络拓扑，配置主机h1和h2的IP地址（h1:10.0.0.1，h2:10.0.0.2），测试两台主机之间的网络连通性
输入pingall：
2. 利用Wireshark工具，捕获拓扑中交换机与控制器之间的通信数据，对OpenFlow协议类型的各类报文进行分析，对照wireshark截图写出你的分析内容。
只支持OpenFlow1.0版本
Hello报文
控制器6633端口，对应交换机51646端口
交换机51646端口，对应6633端口控制器
双方建立连接，并使用OpenFlow1.0
Features_Request报文
控制器6633端口，需要交换机51646端口的特征信息
Set_Config报文
控制器6633端口按照给定的flag和max bytes of packet进行配置交换机的51646端口
Features_Reply报文
交换机51646端口发出自身的特征信息，请控制器6633端口查收
Features 消息包括 OpenFlow Header 和 Features Reply Message
对照Features Reply Message结构：
struct ofp_switch_features{
struct ofp_header header;
uint64_t datapath_id; /*唯一标识 id 号*/
uint32_t n_buffers; /*交缓冲区可以缓存的最大数据包个数*/
uint8_t n_tables; /*流表数量*/
uint8_t pad[3]; /*align to 64 bits*/
uint32_t capabilities; /*支持的特殊功能，具体见 ofp_capabilities*/
uint32_t actions; /*支持的动作，具体见 ofp_actions_type*/
struct ofp_phy_port ports[0]; /*物理端口描述列表，具体见 ofp_phy_port*/
};
对应到抓取到的报文，逐项查看报文内容
Packet_in报文
交换机51646端口（有数据包进来，请指示）--- 控制器6633端口
结合Packet_in的结构：
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*/
uint16_t total_len; /*data字段的长度*/
uint16_t in_port; /*数据包进入交换机时的端口号*/
uint8_t reason; /*发送Packet-in消息的原因，具体见 ofp_packet_in_reason*/
uint8_t pad;
uint8_t data[0]; /*携带的数据包*/
};
分析抓取的数据包，可以发现是因为交换机发现此时自己并没有匹配的流表（Reason: No matching flow (table-miss flow entry) (0)），所以要问控制器如何处理：
OpenFlow 1.0
.000 0001 = Version: 1.0 (0x01)
Type: OFPT_PACKET_IN (10)
Length: 108
Transaction ID: 0
Buffer Id: 0x00000100
Total length: 90
In port: 1
Reason: No matching flow (table-miss flow entry) (0)
Pad: 00
Ethernet II, Src: 96:3f:21:4c:f5:0e (96:3f:21:4c:f5:0e), Dst: IPv6mcast_16 (33:33:00:00:00:16)
Destination: IPv6mcast_16 (33:33:00:00:00:16)
Address: IPv6mcast_16 (33:33:00:00:00:16)
.... ..1. .... .... .... .... = LG bit: Locally administered address (this is NOT the factory default)
.... ...1 .... .... .... .... = IG bit: Group address (multicast/broadcast)
Source: 96:3f:21:4c:f5:0e (96:3f:21:4c:f5:0e)
Address: 96:3f:21:4c:f5:0e (96:3f:21:4c:f5:0e)
.... ..1. .... .... .... .... = LG bit: Locally administered address (this is NOT the factory default)
.... ...0 .... .... .... .... = IG bit: Individual address (unicast)
Type: IPv6 (0x86dd)
Internet Protocol Version 6, Src: ::, Dst: ff02::16
0110 .... = Version: 6
.... 0000 0000 .... .... .... .... .... = Traffic Class: 0x00 (DSCP: CS0, ECN: Not-ECT)
.... 0000 00.. .... .... .... .... .... = Differentiated Services Codepoint: Default (0)
.... .... ..00 .... .... .... .... .... = Explicit Congestion Notification: Not ECN-Capable Transport (0)
.... .... .... 0000 0000 0000 0000 0000 = Flow Label: 0x00000
Payload Length: 36
Next Header: IPv6 Hop-by-Hop Option (0)
Hop Limit: 1
Source: ::
Destination: ff02::16
IPv6 Hop-by-Hop Option
Next Header: ICMPv6 (58)
Length: 0
[Length: 8 bytes]
Router Alert
Type: Router Alert (0x05)
00.. .... = Action: Skip and continue (0)
..0. .... = May Change: No
...0 0101 = Low-Order Bits: 0x05
Length: 2
Router Alert: MLD (0)
PadN
Type: PadN (0x01)
00.. .... = Action: Skip and continue (0)
..0. .... = May Change: No
...0 0001 = Low-Order Bits: 0x01
Length: 0
PadN: <none>
Internet Control Message Protocol v6
Type: Multicast Listener Report Message v2 (143)
Code: 0
Checksum: 0x7a2f [correct]
[Checksum Status: Good]
Reserved: 0000
Number of Multicast Address Records: 1
Multicast Address Record Changed to exclude: ff02::1:ff4c:f50e
Record Type: Changed to exclude (4)
Aux Data Len: 0
Number of Sources: 0
Multicast Address: ff02::1:ff4c:f50e
Packet_out报文
控制器6633端口（请按照我给你的action进行处理） ---> 交换机51646端口
结合Packet_out的结构：
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*/
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*/
uint16_t actions_len; /*action列表的长度，可以用来区分actions和data段*/
struct ofp_action_header actions[0]; /*动作列表*/
uint8_t data[0]; /*数据缓存区，可以存储一个以太网帧，可选*/
}
告诉输出到交换机的51646端口：
OpenFlow 1.0
.000 0001 = Version: 1.0 (0x01)
Type: OFPT_PACKET_OUT (13)
Length: 24
Transaction ID: 0
Buffer Id: 0x00000100
In port: 1
Actions length: 8
Actions type: Output to switch port (0)
Action length: 8
Output port: 65531
Max length: 0
h1 ping h2
Packet_out
flow_mod
结合flow_mod结构:
struct ofp_flow_mod {
struct ofp_header header;
struct ofp_match match; /*流表的匹配域*/
uint64_t cookie; /*流表项标识符*/
uint16_t command; /*可以是ADD,DELETE,DELETE-STRICT,MODIFY,MODIFY-STRICT*/
uint16_t idle_timeout; /*空闲超时时间*/
uint16_t hard_timeout; /*最大生存时间*/
uint16_t priority; /*优先级，优先级高的流表项优先匹配*/
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*/
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*/
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。*/
struct ofp_action_header actions[0]; /*action列表*/
};
分析抓取的flow_mod数据包，控制器通过6633端口向交换机55端口、交换机51646端口下发流表项，指导数据的转发处理：
