2019 SDN上机第7次作业

1.补充并运行basic

/* -*- 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 {
    transition parse_ethernet;
}

state parse_ethernet {
    packet.extract(hdr.ethernet);
    transition select(hdr.ethernet.etherType) {
        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();
}

apply {
    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 {
    packet.emit(hdr.ethernet);
    packet.emit(hdr.ipv4);
}
}

/*************************************************************************
***********************  S W I T C H  *******************************
*************************************************************************/

V1Switch(
MyParser(),
MyVerifyChecksum(),
MyIngress(),
MyEgress(),
MyComputeChecksum(),
MyDeparser()
) main;

• 进入basic所在文件夹，命令make run编译运行
  
  
• 命令pingall测试连通性
  

2.补充并运行basic_tunnel

  #include <core.p4>
  #include <v1model.p4>
  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;
  bit<16>   etherType;
  }
  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 */
  }
  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 {
    transition parse_ethernet;
  }
  state parse_ethernet {
    packet.extract(hdr.ethernet);
    transition select(hdr.ethernet.etherType) {
        TYPE_MYTUNNEL: parse_myTunnel;
        TYPE_IPV4: parse_ipv4;
        default: accept;
    }
  }
  state parse_myTunnel {
    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();
  }
  action myTunnel_forward(egressSpec_t port) {
    standard_metadata.egress_spec = port;
  }

  table myTunnel_exact {
    key = {
        hdr.myTunnel.dst_id: exact;
    }
    actions = {
        myTunnel_forward;
        drop;
    }
    size = 1024;
    default_action = drop();
  }

  apply {
    if (hdr.ipv4.isValid() && !hdr.myTunnel.isValid()) {
        // Process only non-tunneled IPv4 packets
        ipv4_lpm.apply();
    }

    if (hdr.myTunnel.isValid()) {
        // process tunneled packets
        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);
    packet.emit(hdr.myTunnel);
    packet.emit(hdr.ipv4);
  }
  }
  /*************************************************************************
  ***********************  S W I T C H  *******************************
  *************************************************************************/

  V1Switch(
  MyParser(),
  MyVerifyChecksum(),
  MyIngress(),
  MyEgress(),
  MyComputeChecksum(),
  MyDeparser()
  ) main;

• 进入basic_tunnel所在文件夹，命令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

接着在主机1的xterm界面输入./send.py 10.0.2.2 "I am linbei"

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

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 "I am linbei" --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

原因：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

P4是一门主要用于数据平面的编程语言，主要用于编程程序以下达指令给数据转发平面的设备(如交换机、网卡、防火墙、过滤器等)如何处理数据包，P4试图在从根本上改变我们设计网络系统的方式。但由于P4编程语言更新较快，对于语法等的掌握还不够全面，在之后将继续加强学习。