[6bone] Re: link local for tunnel endpoints

[Petr Baudis]

Dear diary, on Sun, Oct 26, 2003 at 01:49:56PM CET, I got a letter,
where Dan Reeder <dan@reeder.name> told me, that...
> Hey guys
> in light of the recent spirited discussions regarding ptp subnets, I was
> wondering whether anyone has used or is using the link local addressing for
> the endpoints. (I'm not too sure whether it is still called link local in
> this case, as it is quite different from typical MAC-based addressing)
> 
> here's an example of my tunnel:
> 
> ip tunnel add sixbone mode sit remote 203.149.69.35 local 202.173.147.67
> ip link set sixbone up
> ip tunnel change sixbone ttl 255
> ip link set mtu 1472 dev sixbone
> route add -A inet6 ::/0 gw fe80::cb95:4523 dev sixbone
> 
> fe80::cb95:4523 is just the remote ip converted to hex and set with a link
> local prefix.
> 
> Now because my local router and the remote router also have valid 2001::
> global addressing (on mine for the /64 on another interface, on the remote
> for other purposes), so traceroutes back and forth are going through just
> fine. I realise that every device needs a globally reachable ip set on it
> somewhere, even on a loopback interface, to be reachable.
> But are there any operational down sides or gotchas that would prove this
> type of addressing to be unsafe or impractical for use?

FYI, this is exactly what we at XS26 do (sorry for such a late reply),
except for BGP peerings. All user tunnels are tunneled over link-local.

It's as simple as:

iptunnel add $TUNLIF mode sit local $MYIPv4 remote $XSIPv4 ttl 64
ifconfig $TUNLIF up
route -A inet6 add 2000::/3 dev $TUNLIF

Kind regards,

-- 
 
				Petr "Pasky" Baudis
.
To get something done, a committee should consist of no more than three
persons, two of them absent.
.
Stuff: http://pasky.ji.cz/