The router must use its loopback or OOB management interface address as the source address when originating NTP traffic.
Using a loopback address as the source address offers a multitude of uses for security, access, management, and scalability of routers. It is easier to construct appropriate ingress filters for router management plane traffic destined to the network management subnet since the source addresses will be from the range used for loopback interfaces instead of a larger range of addresses used for physical interfaces. Log information recorded by authentication and syslog servers will record the router’s loopback address instead of the numerous physical interface addresses. NTP messages sent to management servers should use the loopback address as the source address.
Configure the device to use its loopback or OOB management interface address as the source address when originating NTP traffic.
Review the configuration and verify the loopback interface address is used as the source address when originating NTP traffic. If the device is managed from an OOB management network, the OOB interface must be used instead. The configuration should look similar as shown in the following example: interface loopback 0 ip address 10.10.2.1 255.255.255.255 … ntp server 18.104.22.168 ntp server 22.214.171.124 ntp source Loopback0 Note: IOS allows multiple loopback interfaces to be defined.
Information Assurance Officer