cvs commit: src/sys/netinet ip_carp.c

[Robert Watson]

On Wed, 26 Oct 2005, Yar Tikhiy wrote:

>  Since carp(4) interfaces presently are kinda fake yet possess
>  IP addresses, mark them with LOOPBACK so that routing daemons
>  take them easy for link-state routing protocols.
>
>  Reviewed by:    glebius

Be aware that several network protocols, including IPv4 and IPv6, have 
special-case handling for interfaces tagged as IFF_LOOPBACK.  I don't know 
whether this is a problem or not, but it's something you might want to 
investigate.  I've previously run into problems with if_disc because it's 
marked as IFF_LOOPBACK and IPv6 has tried to use it for things that are 
not appropriate with if_disc -- unfortunately, I don't remember the 
details.  I think we may actually be in need of either a new flag, 
IFF_OKSODONTTREATTHISQUITELIKEANINTERFACE, or maybe a more reliable way 
for protocols to ask if an interface is a loopback interface or not.

Robert N M Watson