ICMP: Time-to-live (TTL) expiry with source address

You can configure your device to use an IPv4 address as the source address for ICMP time-to-live (TTL) expiry error messages. This means you can configure the loopback address as the source address in response to ICMP error packets. Doing this is useful when you cannot use the device address for traceroute purposes because you have duplicate IPv4 addresses in your network. Specify the address using the ttl-expired-source-address source-address option at the [edit system icmp] hierarchy level. The source address must be an IPv4 address. This configuration applies only to ICMP TTL expiry messages. Other ICMP error reply messages continue to use the address of the ingress interface as the source address.