[support] About the Neighbor Unreachability Detection

[Arnaud Ebalard]

Hi,

Angel Bartomeu Bonillo <angelbartomeu at gmail.com> writes:

> How is the Neighbor Unreachability Detection implemented in the mip6daemon?
> Does the daemon relay on the upper protocols to detect the two-ways
> connection, does it uses Router Solicitation and Neighbor Solicitation or
> does it use both methods as specified in the RFC 2461?
>
> More specifically my question could be: If a router send Unsolicited Router
> Advertisement to a node running the mip6daemon but the router does not
> implement any method to respond to Router Solicitation by means of a
> Solicitated Router Advertisements, Does the node consider the router
> reachable? Is there any problem in this scenario?

I may be wrong (i.e. you'll have to test it to be sure) but I think what
will happen is the following:  

UMIP will configure an address based on advertised prefix. If the
router does not respond to solicited RS, this will obviously take some
time depending on the interval configured between unsolicited RA.

Then, because the neighbor cache is filled with the information on the
router with the NUD_PROBE flag set (see call to neigh_add() in
md_probe_router() in movement.c), UMIP will invalidate the router at
some point if it does not receive a NA. It may use it during that time.

May I ask what kind of router/scenario you are trying to support?

Cheers,

a+