300-730 · Question #162
Which command must be configured on the tunnel interface of a FlexVPN spoke to receive a dynamic IP address from the hub?
The correct answer is A. ip address negotiated. On a FlexVPN spoke tunnel interface, ip address negotiated triggers IKEv2 Config Payload to request a virtual IP from the hub, enabling dynamic address assignment over the tunnel.
Question
Options
- Aip address negotiated
- Bip unnumbered
- Cip address dhcp
- Dip address pool
How the community answered
(36 responses)- A89% (32)
- B8% (3)
- C3% (1)
Why each option
On a FlexVPN spoke tunnel interface, ip address negotiated triggers IKEv2 Config Payload to request a virtual IP from the hub, enabling dynamic address assignment over the tunnel.
The ip address negotiated command tells the IOS tunnel interface to use the IKEv2 Configuration Payload (CFG_REQUEST/CFG_REPLY) mechanism to request a virtual IP address from the FlexVPN hub. This is the only command that integrates with IKEv2's built-in address assignment feature. Without it, the spoke cannot dynamically obtain a tunnel overlay address from the hub's IP local pool.
ip unnumbered borrows an IP from another local interface and does not request an address from the hub.
ip address dhcp requests an address via DHCP, which is not the FlexVPN/IKEv2 address assignment mechanism.
ip address pool is not a valid Cisco IOS tunnel interface command.
Concept tested: FlexVPN IKEv2 dynamic address assignment via Config Payload
Source: https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/sec_conn_ikevpn/configuration/xe-16/sec-flex-vpn-xe-16-book/sec-flex-vpn-spoke-spoke.html
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