ICMP Extensions for Unnumbered Interfaces
This memo defines extensions to ICMP that permit identification of unnumbered interfaces. The interface the triggering IPv4 or IPv6 packet was received upon can be identified by appending an ifIndex and/or a string describing the interface. These extensions are defined to facilitate troubleshooting in network with unnumbered interfaces. Additionally, to facilitate debugging of numbered interfaces, an IPv4 or IPv6 address of the interface the triggering IPv4 or IPv6 packet was received upon can be identified by appending an IPv4 or IPv6 address.