Protocol Independent IPv4 Routing GRE Tunnels


How GRE Keepalives Work

How to configure a GRE tunnel

Why Can’t I Browse the Internet when Using a GRE Tunnel?

GRE Tunnel Interface States and What Impacts Them


  • デオフォルトのUp/Down 判定は宛先に到達性があること
R1(config)#interface Tunnel1
R1(config-if)# ip address
R1(config-if)# tunnel source FastEthernet1/0
R1(config-if)# tunnel destination


  • keepalive を使うと、宛先に到達性があっても、keepaliveを元にUp/Downを判定できる
  • 送信間隔とリトライを指定できる
R1(config-if)#keepalive ?
  <0-32767>  Keepalive period (default 10 seconds)

R1(config-if)#keepalive 1 ?
  <1-255>  Keepalive retries