• 2019 SDN上机第7次作业


    1.根据P4教程,将basic和basic_tunnel两个案例程序补充完整,成功运行。

    任务是实现基础的交换机转发数据包功能
    补充后代码如下:

    /* -*- P4_16 -*- */
    #include <core.p4>
    #include <v1model.p4>
    
    const bit<16> TYPE_IPV4 = 0x800;
    
    /*************************************************************************
    *********************** H E A D E R S  ***********************************
    *************************************************************************/
    
    typedef bit<9>  egressSpec_t;
    typedef bit<48> macAddr_t;
    typedef bit<32> ip4Addr_t;
    
    header ethernet_t {
        macAddr_t dstAddr;
        macAddr_t srcAddr;
        bit<16>   etherType;
    }
    
    header ipv4_t {
        bit<4>    version;
        bit<4>    ihl;
        bit<8>    diffserv;
        bit<16>   totalLen;
        bit<16>   identification;
        bit<3>    flags;
        bit<13>   fragOffset;
        bit<8>    ttl;
        bit<8>    protocol;
        bit<16>   hdrChecksum;
        ip4Addr_t srcAddr;
        ip4Addr_t dstAddr;
    }
    
    struct metadata {
        /* empty */
    }
    
    struct headers {
        ethernet_t   ethernet;
        ipv4_t       ipv4;
    }
    
    /*************************************************************************
    *********************** P A R S E R  ***********************************
    *************************************************************************/
    
    parser MyParser(packet_in packet,
                    out headers hdr,
                    inout metadata meta,
                    inout standard_metadata_t standard_metadata) {
    
        state start {
            /* TODO: add parser logic */
    	transition parse_ethernet;
        }
        state parse_ethernet
        {   
        packet.extract(hdr.ethernet);   /*根据定义的数据结构提取以太包头*/
            transition select(hdr.ethernet.etherType) {  /*根据协议类型选择下一个状态*/
                0x0800: parse_ipv4;   /*设置为0x0800,parse_ipv4状态*/
            default: accept;      /*默认设置为接受*/
            }
        }
        state parse_ipv4
        {        
        packet.extract(hdr.ipv4); /*提取ip包的头部*/
            transition accept;
        }
    }
    
    
    /*************************************************************************
    ************   C H E C K S U M    V E R I F I C A T I O N   *************
    *************************************************************************/
    
    control MyVerifyChecksum(inout headers hdr, inout metadata meta) {   
        apply {  }
    }
    
    
    /*************************************************************************
    **************  I N G R E S S   P R O C E S S I N G   *******************
    *************************************************************************/
    
    control MyIngress(inout headers hdr,
                      inout metadata meta,
                      inout standard_metadata_t standard_metadata) {
        action drop() {
            mark_to_drop(standard_metadata);
        }
        
        action ipv4_forward(macAddr_t dstAddr, egressSpec_t port) {
            /* TODO: fill out code in action body */
            hdr.ethernet.srcAddr = hdr.ethernet.dstAddr;   /*原数据包的源地址改为目的地址*/
            hdr.ethernet.dstAddr = dstAddr;
        standard_metadata.egress_spec = port; /*从参数中获取要输出的端口*/
        hdr.ipv4.ttl = hdr.ipv4.ttl - 1;
        }
        
        table ipv4_lpm {
            key = {                                 
                hdr.ipv4.dstAddr: lpm;
            }
            actions = {
                ipv4_forward;
                drop;
                NoAction;
            }
            size = 1024;
            default_action = NoAction();
        }
        
        apply {
            /* TODO: fix ingress control logic
             *  - ipv4_lpm should be applied only when IPv4 header is valid
             */
    	if(hdr.ipv4.isValid())
    	{
    	        ipv4_lpm.apply();
    	}
        }
    }
    
    /*************************************************************************
    ****************  E G R E S S   P R O C E S S I N G   *******************
    *************************************************************************/
    
    control MyEgress(inout headers hdr,
                     inout metadata meta,
                     inout standard_metadata_t standard_metadata) {
        apply {  }
    }
    
    /*************************************************************************
    *************   C H E C K S U M    C O M P U T A T I O N   **************
    *************************************************************************/
    
    control MyComputeChecksum(inout headers hdr, inout metadata meta) {
         apply {
    	update_checksum(
    	    hdr.ipv4.isValid(),
                { hdr.ipv4.version,
    	      hdr.ipv4.ihl,
                  hdr.ipv4.diffserv,
                  hdr.ipv4.totalLen,
                  hdr.ipv4.identification,
                  hdr.ipv4.flags,
                  hdr.ipv4.fragOffset,
                  hdr.ipv4.ttl,
                  hdr.ipv4.protocol,
                  hdr.ipv4.srcAddr,
                  hdr.ipv4.dstAddr },
                hdr.ipv4.hdrChecksum,
                HashAlgorithm.csum16);
        }
    }
    
    
    /*************************************************************************
    ***********************  D E P A R S E R  *******************************
    *************************************************************************/
    
    control MyDeparser(packet_out packet, in headers hdr) {
        apply {
            /* TODO: add deparser logic */
    	packet.emit(hdr.ethernet);
            packet.emit(hdr.ipv4);
        }
    }
    
    /*************************************************************************
    ***********************  S W I T C H  *******************************
    *************************************************************************/
    
    V1Switch(
    MyParser(),
    MyVerifyChecksum(),
    MyIngress(),
    MyEgress(),
    MyComputeChecksum(),
    MyDeparser()
    ) main;
    

    接着打开终端,进入basic文件夹,输入make run编译运行
    (或许会用到的语句:)

    make stop
    make clean
    make run
    



    在mininet界面进行ping通测试,先是将数据包从h1发送到h2
    再就是进行全部主机之间的连通测试
    如果都连通,证明代码补充成功

    2.说明案例程序的编译执行流程。

    任务是定义新的头部类型并修改交换机部分的代码,从而将消息封装进IP数据包并让目标端口使用新的头部类型
    补充后代码如下:

    /* -*- P4_16 -*- */
    #include <core.p4>
    #include <v1model.p4>
    
    // NOTE: new type added here
    const bit<16> TYPE_MYTUNNEL = 0x1212;
    const bit<16> TYPE_IPV4 = 0x800;
    
    /*************************************************************************
    *********************** H E A D E R S  ***********************************
    *************************************************************************/
    
    typedef bit<9>  egressSpec_t;
    typedef bit<48> macAddr_t;
    typedef bit<32> ip4Addr_t;
    
    header ethernet_t {
        macAddr_t dstAddr;
        macAddr_t srcAddr;
        bit<16>   etherType;
    }
    
    // NOTE: added new header type
    header myTunnel_t {
        bit<16> proto_id;
        bit<16> dst_id;
    }
    
    header ipv4_t {
        bit<4>    version;
        bit<4>    ihl;
        bit<8>    diffserv;
        bit<16>   totalLen;
        bit<16>   identification;
        bit<3>    flags;
        bit<13>   fragOffset;
        bit<8>    ttl;
        bit<8>    protocol;
        bit<16>   hdrChecksum;
        ip4Addr_t srcAddr;
        ip4Addr_t dstAddr;
    }
    
    struct metadata {
        /* empty */
    }
    
    // NOTE: Added new header type to headers struct
    struct headers {
        ethernet_t   ethernet;
        myTunnel_t   myTunnel;
        ipv4_t       ipv4;
    }
    
    /*************************************************************************
    *********************** P A R S E R  ***********************************
    *************************************************************************/
    
    // TODO: Update the parser to parse the myTunnel header as well
    parser MyParser(packet_in packet,
                    out headers hdr,
                    inout metadata meta,
                    inout standard_metadata_t standard_metadata) {
    
        state start {
            transition parse_ethernet;
        }
    
        state parse_ethernet {
            packet.extract(hdr.ethernet);
            transition select(hdr.ethernet.etherType) {
                TYPE_IPV4 : parse_ipv4;
                default : accept;
            }
        }
        state parse_myTunnel /*要求更新解析器,解析mytunnel头部,那么添加mytunnel头类型。其中类型字段为16位的proto_id*/
        {
            packet.extract(hdr.myTunnel);
            transition select(hdr.myTunnel.proto_id) 
        {
                TYPE_IPV4: parse_ipv4;
                default: accept;
            }
        }
    
        state parse_ipv4 {
            packet.extract(hdr.ipv4);
            transition accept;
        }
    
    }
    
    /*************************************************************************
    ************   C H E C K S U M    V E R I F I C A T I O N   *************
    *************************************************************************/
    
    control MyVerifyChecksum(inout headers hdr, inout metadata meta) {   
        apply {  }
    }
    
    
    /*************************************************************************
    **************  I N G R E S S   P R O C E S S I N G   *******************
    *************************************************************************/
    
    control MyIngress(inout headers hdr,
                      inout metadata meta,
                      inout standard_metadata_t standard_metadata) {
        action drop() {
            mark_to_drop(standard_metadata);
        }
        
        action ipv4_forward(macAddr_t dstAddr, egressSpec_t port) {
            standard_metadata.egress_spec = port;
            hdr.ethernet.srcAddr = hdr.ethernet.dstAddr;
            hdr.ethernet.dstAddr = dstAddr;
            hdr.ipv4.ttl = hdr.ipv4.ttl - 1;
        }
        
        table ipv4_lpm {
            key = {
                hdr.ipv4.dstAddr: lpm;
            }
            actions = {
                ipv4_forward;
                drop;
                NoAction;
            }
            size = 1024;
            default_action = drop();
        }
    
        // TODO: declare a new action: myTunnel_forward(egressSpec_t port)
    	action myTunnel_forward(egressSpec_t port) {
            standard_metadata.egress_spec = port;
        }
    
        // TODO: declare a new table: myTunnel_exact
        // TODO: also remember to add table entries!
        table myTunnel_exact {   
            key = {
                hdr.myTunnel.dst_id: exact;
            }
            actions = {
                myTunnel_forward;
                drop;
            }
            size = 1024;
            default_action = drop();
        }
    
        apply {
            // TODO: Update control flow
    
            if (hdr.ipv4.isValid()&&!hdr.myTunnel.isValid()) {
                ipv4_lpm.apply();
            }
        	if (hdr.myTunnel.isValid()) {
                myTunnel_exact.apply();
            }
        }
    }
    
    /*************************************************************************
    ****************  E G R E S S   P R O C E S S I N G   *******************
    *************************************************************************/
    
    control MyEgress(inout headers hdr,
                     inout metadata meta,
                     inout standard_metadata_t standard_metadata) {
        apply {  }
    }
    
    /*************************************************************************
    *************   C H E C K S U M    C O M P U T A T I O N   **************
    *************************************************************************/
    
    control MyComputeChecksum(inout headers  hdr, inout metadata meta) {
         apply {
    	update_checksum(
    	    hdr.ipv4.isValid(),
                { hdr.ipv4.version,
    	      hdr.ipv4.ihl,
                  hdr.ipv4.diffserv,
                  hdr.ipv4.totalLen,
                  hdr.ipv4.identification,
                  hdr.ipv4.flags,
                  hdr.ipv4.fragOffset,
                  hdr.ipv4.ttl,
                  hdr.ipv4.protocol,
                  hdr.ipv4.srcAddr,
                  hdr.ipv4.dstAddr },
                hdr.ipv4.hdrChecksum,
                HashAlgorithm.csum16);
        }
    }
    
    /*************************************************************************
    ***********************  D E P A R S E R  *******************************
    *************************************************************************/
    
    control MyDeparser(packet_out packet, in headers hdr) {
        apply {
            packet.emit(hdr.ethernet);
            // TODO: emit myTunnel header as well
    		packet.emit(hdr.myTunnel);
            packet.emit(hdr.ipv4);
        }
    }
    
    /*************************************************************************
    ***********************  S W I T C H  *******************************
    *************************************************************************/
    
    V1Switch(
    MyParser(),
    MyVerifyChecksum(),
    MyIngress(),
    MyEgress(),
    MyComputeChecksum(),
    MyDeparser()
    ) main;
    
    

    接着打开终端,进入basic_tunnel文件夹,输入make run编译运行


    在mininet命令提示符界面输入xterm h1 h2来模拟两个终端

    先在主机2的xterm界面输入

    ./receive.py
    

    启动服务器

    接着在主机1的xterm界面输入如下,发送消息

    ./send.py 10.0.2.2 "p4 is cool"
    

    检查主机2的xterm界面,可以看到已经接收到了信息,内容包括以太头部,IP头部,TCP头部以及发送的信息

    再发一个"p34 is cool"
    一起截个图

    接着在主机1的xterm界面修改IP地址,再一次发送信息

    ./send.py 10.0.3.3 "P4 is cool" --dst_id 2
    


    检查主机2的xterm界面,可以看到已经接收到了信息,IP地址变更为了主机3的地址,这是因为交换机不再使用IP头部数据来定位,而是用数据包中的隧道头部数据来定位

    3.提交你对P4的认识和体会。

    SDN是网络的未来,P4是SDN的未来,基于openflow的传统SDN专注于可编程的控制平面,可以自定义芯片对于数据包的处理方式,添加自己的新功能,新协议,或者对原有协议栈进行优化,更合理的分配片上资源。openflow利用匹配域可抽象整个TCP/IP协议栈的绝大部分功能,而P4可以完整描述openflow的功能。

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  • 原文地址:https://www.cnblogs.com/0717fei/p/12026068.html
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