一实验目的
1、能够运用 wireshark 对 OpenFlow 协议数据交互过程进行抓包;
2、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。
二、实验环境
Ubuntu 20.04 Desktop amd64
三、实验要求
(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。
2.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。
HELLO(控制器6633端口 ---> 交换机48996端口)
1.HELLO(交换机6633端口(我最高能支持OpenFlow 1.0) ---> 控制器48996端口)
2.Features Request(控制器6633端口(我需要你的特征信息) ---> 交换机48982端口)![](/i/l/?n=22&i=blog/2980642/202210/2980642-20221005234000080-406641710.png)
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48982端口)![](/i/l/?n=22&i=blog/2980642/202210/2980642-20221005234026270-1423081005.png)
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48982端口(这是我的特征信息,请查收) ---> 控制器6633端口)
6.Packet_in
交换机48982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48996端口、交换机44214端口下发流表项,指导数据的转发处理
8.Packet_out控制器6633端口向交换机48982端口发送数据,并告知交换机输出到65531端口。
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
(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,了解OpenFlow主要消息类型对应的数据结构定义
OpenFlow主要消息类型
enum ofp_type { /* Immutable messages. */ OFPT_HELLO, /* Symmetric message */ OFPT_ERROR, /* Symmetric message */ OFPT_ECHO_REQUEST, /* Symmetric message */ OFPT_ECHO_REPLY, /* Symmetric message */ OFPT_VENDOR, /* Symmetric message */ /* Switch configuration messages. */ OFPT_FEATURES_REQUEST, /* Controller/switch message */ OFPT_FEATURES_REPLY, /* Controller/switch message */ OFPT_GET_CONFIG_REQUEST, /* Controller/switch message */ OFPT_GET_CONFIG_REPLY, /* Controller/switch message */ OFPT_SET_CONFIG, /* Controller/switch message */ /* Asynchronous messages. */ OFPT_PACKET_IN, /* Async message */ OFPT_FLOW_REMOVED, /* Async message */ OFPT_PORT_STATUS, /* Async message */ /* Controller command messages. */ OFPT_PACKET_OUT, /* Controller/switch message */ OFPT_FLOW_MOD, /* Controller/switch message */ OFPT_PORT_MOD, /* Controller/switch message */ /* Statistics messages. */ OFPT_STATS_REQUEST, /* Controller/switch message */ OFPT_STATS_REPLY, /* Controller/switch message */ /* Barrier messages. */ OFPT_BARRIER_REQUEST, /* Controller/switch message */ OFPT_BARRIER_REPLY, /* Controller/switch message */ /* Queue Configuration messages. */ OFPT_QUEUE_GET_CONFIG_REQUEST, /* Controller/switch message */ OFPT_QUEUE_GET_CONFIG_REPLY /* Controller/switch message */ };
Hello
/* 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源码参数格式与HELLO的一致
features reply
/* 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. */ };
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; };
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. */ };
packet_in
/* 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. */ }; OFP_ASSERT(sizeof(struct ofp_packet_in) == 20);
packet_out
/* 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);
flow_mod
/* 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. */ }; OFP_ASSERT(sizeof(struct ofp_flow_mod) == 72);
三、总结
本次实验与上次实验相比,一个是先pingall再抓包,另一个是先抓包再pingall,在熟悉上次实验的过程之后实验做起来会比较容易。
标签:OFPT,struct,OpenFlow,端口,实践,header,ofp,实验,message From: https://www.cnblogs.com/123456aabbssdd/p/16756861.html