create packet-generator interface pg0
create packet-generator interface pg1
set int ip address pg1 192.168.2.1/24
set ip arp pg1 192.168.2.2 6:5:4:3:2:1 static
create gre tunnel dst 192.168.2.2 src 192.168.2.1 teb

set int state pg0 up
set int state pg1 up
set int state gre0 up
set int l2 xconnect pg0 gre0
set int l2 xconnect gre0 pg0

packet-generator new {
  name tx
  limit -1
  node ethernet-input
  size 64-64
  interface pg0
  data {
    0x8881: 4:4:4:4:4:4 -> 5:5:5:5:5:5
    incrementing 100
  }
}

packet-generator new {
  name rx
  limit -1
  node ip4-input
  size 72-72
  interface pg1
  data {
    GRE: 192.168.2.2 -> 192.168.2.1
      teb
        0x8881: 4:4:4:4:4:4 -> 5:5:5:5:5:5
        incrementing 100
  }
}

packet-generator enable