On Thu, Jan 02, 2014 at 04:13:40PM +0800, chenweilong wrote:

Can you give more explanation about this please?

If you look at the routing table for local addresses (ip -6 route list table
local), you see that every address which is RTF_LOCAL (and thus passes up the
packets via ip6_input) has as its device the loopback device.

In case you shutdown loopback you clear all those routes, thus incoming
packets won't find the corresponding rt6_info which directs the packets to
passed up the stack.

I guess it was done to satisfy the scoped architecture of IPv6.

Does this help you?