How to verify if the GRE Tunnel is Operational

Now that we have configured GRE Tunnel, let us see how to check whether it is operational or not.

R1#sh ip int brief
Interface    IP-Address   OK? Method Status      Protocol
Tunnel0       172.16.1.1   YES manual up        up

R2#sh ip int brief
Interface    IP-Address   OK? Method Status     Protocol
Tunnel0      172.16.1.2   YES manual up         up

R1#sh int tun 0
Tunnel0 is up, line protocol is up
  Hardware is Tunnel
  Internet address is 172.16.1.1/24
  MTU 1514 bytes, BW 9 Kbit, DLY 500000 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation TUNNEL, loopback not set
  Keepalive not set
  Tunnel source 10.1.1.1, destination 10.1.1.2
  Tunnel protocol/transport GRE/IP
    Key disabled, sequencing disabled
    Checksumming of packets disabled
  Tunnel TTL 255
  Fast tunneling enabled
  Tunnel transmit bandwidth 8000 (kbps)
  Tunnel...