mesh portal discovery

[John Watlington]

On Jan 9, 2008, at 2:40 PM, David Woodhouse wrote:

>
> On Wed, 2008-01-09 at 14:33 -0500, John Watlington wrote:
>> Unsolicited RAs for IPv6 mean that IPv6 isn't the panacea to this
>> problem. It's easy to discover the shortest way out of the mesh
>> (nearest mesh portal), but setting up the larger mesh networkl
>> infrastucture means you also need to provide a way to route packets
>> back INTO the mesh through the MPP nearest the destination laptop.
>>
>> I have yet to see a good description of how to make IPv6 work  
>> right on
>> a mesh with multiple portals.    One would be welcome!
>
> I talked to cscott and Michail about this briefly when I was in Boston
> in December. I suspect we should turn off the automatic response to RA
> in the kernel, and handle it in userspace. We need some special  
> handling
> in userspace anyway, to pick up DNS server details from RA. We can  
> also
> check the mesh path length to the origin of each RA we see, and choose
> the best one.

Sounds like a plan.  Sometime next week we should start outlining the
work that needs to happen.

>> I have such a method for IPv4 defined, but due to an error in
>> modifying the DHCP client, it doesn't handle laptops moving around in
>> the mesh once they've chosen an MPP.   (BTW, the error was mine)
>
> Is there a hack which would work around that -- like reducing the  
> lease
> time?

Heh. JG wants to increase the lease time --- I want to reduce it.    
It doesn't
really make a difference, as once the lease time is expired the dhclient
first tries to request the existing lease from the previous DHCP server.
As long as it can communicate with it by hopping through the mesh, it  
will
renew the existing lease and never discover a closer MPP/DHCP server
This was the problem that prompted my original message on this thread.

wad