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last-resort-circuit

vpn 0 interface tunnel-interface last-resort-circuit—Use the tunnel interface as the circuit of last resort (on vEdge routers). By default, this feature is disabled, and the tunnel interface is not considered to be the circuit of last resort.

There is a delay of 7 seconds before switching back to the primary tunnel interface from a circuit of last resort. This delay is to ensure that the primary interface is once again fully operational and is not still flapping.

When you configure a tunnel interface to be a last-resort circuit, the cellular modem becomes dormant and no traffic is sent over the circuit. However, the cellular modem is kept in online mode so that the modem radio can be monitored at all times and to allow for faster switchover in the case the tunnel interface needs to be used as the last resort.

To minimize the amount of extraneous data plane traffic on a cellular interface that is a circuit of last resort, increase the BFD Hello packet interval and disable PMTU discover.

vManage Feature Template

For vEdge routers only:

Configuration ► Templates ► VPN Interface Ethernet

Command Hierarchy

vpn 0
  interface interface-name
    tunnel-interface
      [no] last-resort-circuit

Options

None

Example

Configure the cellular0 interface to be the circuit of last resort for the vEdge router:

vEdge# show running-config vpn 0 interface cellular0
vpn 0
 interface cellular0
  ip dhcp-client
  tunnel-interface
   encapsulation ipsec
   color lte
   last-resort-circuit
   no allow-service bgp
   allow-service dhcp
   allow-service dns
   allow-service icmp
   no allow-service sshd
   no allow-service netconf
   no allow-service ntp
   no allow-service ospf
   no allow-service stun
  !
  clear-dont-fragment
  mtu                 1428
  profile             1
  no shutdown
 !
!
vEdge# show running-config bfd
bfd color lte
 hello-interval 300000
 no pmtu-discovery
!

Release Information

Command introduced in Viptela Software Release 16.2.

Additional Information

See the Configuring Interfaces article for your software release.
bfd color hello-interval
bfd color pmtu-discovery

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