On Mon, 21 Jul 2008, Hemant Singh (shemant) wrote:
The traffic direction of the Loopback interface in the generic router sense is that the Loopback interface does not face any traffic direction. However, the Loopback interface for the CPE Router can initiate IPv6 address acquisition via the WAN interface to the SP. The architecture, I am referring to is Integrated Routing and Bridging (IRB) - google it. Such routing can send the RA to other virtual interfaces of a router.
For me, a loopback interface is a virtual interface, as per your first part. "interface loopback 0" in cisco routers.
If the IP address is in IRB, then it's no longer a loopback interface, it's a bridge- or vlan-interface.
-- Mikael Abrahamsson email: swmike@swm.pp.se