P4语言练习

练习一：Basic

本练习的目的是编写一个P4程序 实现了基本的转发。 为了简单起见，我们只要实现IPv4转发。
对于IPv4转发，交换机必须完成以下操作

1. 更新源MAC地址和目的MAC地址
2. 减少IP报头中的生存时间(time-to-live, TTL)
3. 将数据包发送到适当的端口

你的开关将有一个单表，控制平面将用静态规则填充。 每个规则将一个IP地址映射到下一跳的MAC地址和输出端口。 我们已经定义了控制平面的规则，所以只需要实现数据平面
P4程序的逻辑。

查看控制平面的代码

{
  "target": "bmv2",
  "p4info": "build/basic.p4info",
  "bmv2_json": "build/basic.json",
  "table_entries": [
    {
      "table": "MyIngress.ipv4_lpm",
      "default_action": true,
      "action_name": "MyIngress.drop",
      "action_params": { }
    },
    {
      "table": "MyIngress.ipv4_lpm",
      "match": {
        "hdr.ipv4.dstAddr": ["10.0.1.1", 32]
      },
      "action_name": "MyIngress.ipv4_forward",
      "action_params": {
        "dstAddr": "00:00:00:00:01:01",
        "port": 1
      }
    },
    {
      "table": "MyIngress.ipv4_lpm",
      "match": {
        "hdr.ipv4.dstAddr": ["10.0.2.2", 32]
      },
      "action_name": "MyIngress.ipv4_forward",
      "action_params": {
        "dstAddr": "00:00:00:02:02:00",
        "port": 2
      }
    },
    {
      "table": "MyIngress.ipv4_lpm",
      "match": {
        "hdr.ipv4.dstAddr": ["10.0.3.3", 32]
      },
      "action_name": "MyIngress.ipv4_forward",
      "action_params": {
        "dstAddr": "00:00:00:03:03:00",
        "port": 3
      }
    }
  ]
}