The ability to configure Ethernet Unnumbered interfaces has been added to support some service types for IPv4. The unnumbered interface capability has been available for other interface types on SR OS. Unnumbered Ethernet allows point-to-point interfaces to borrow the address from other interfaces such as system or loopback interfaces.
This feature enables unnumbered interfaces for some routing protocols (IS-IS and OSPF). Support for routing is dependent on the respective routing protocol and service. This feature also adds support for both dynamic and static ARP for unnumbered Ethernet interfaces to allow interworking with unnumbered interfaces that may not support dynamic ARP.
The use of unnumbered interface has no effect on IPv6 routes but the unnumbered command must only be used in cases where IPv4 is active (IPv4 only and mixed IPv4/IPv6 environments). When using an unnumbered interface for IPv4, the loopback address used for the unnumbered interface must have IPv4 address. Also, interface type for the unnumbered interface is automatically point-to-point.