To enable IPv6 Shortcuts on the BEBs and to advertise the local BEB to other IS-IS nodes, you must configure a circuitless IPv6 address (loopback address) and specify this address as the IS-IS source address. This source address is automatically advertised into IS-IS using TLV 236.
IPv6 Shortcuts support Circuitless IPv6 (CLIPv6), which ensures uninterrupted connectivity to the switch as long as there is an actual path to reach it. This route always exists and the circuit is always up because there is no physical attachment.