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Re: More complicated ipv6 routing with radvd



Hi. Thanks for the reply.

I think I got confused by radvd having the box advertise a default route. I think it'd be lots easier if I moved the wireless subnet to the firewall, though. I'll do that this weekend, and it's probably time to learn some more about routing too.

Thanks for your help, all.

 .....Ron

On Dec 26, 2008, at 4:15, Bernhard Schmidt <berni@birkenwald.de> wrote:

Ron Murray <rjmx@rjmx.net> wrote:

Hello Ron,

I have a slightly more complicated network topology than normal:


                  Debian box as
(Internet) <-----> firewall/router <-------- Ethernet LAN --------- > etc
                       (1)                      |
                                                |
                                            Debian box
                                            as router (2)
                                                |
                                                |
                                            Wireless LAN
                                                |
                                                |
                                               etc

(I decided long ago that I felt much safer if I had the wireless net on
a separate subnet: I can use box (2) to protect my Ethernet net).

I set up ipv6 on the network for internal use (to gain experience with it) last year some time, and ran radvd on box (2) to do its usual stuff, including routing information. It set itself up as a default router, but that didn't matter at the time since I wasn't planning on going to the
Internet on ipv6.

I've now set up a tunnel with Hurricane Electric and got it working on box (1). The next step is to set up routing so that I can use IPv6 from
other machines on the network, and here's where I ran into problems.

I presume box (1) is the right place to run radvd advertising itself as
a default route. That part works. radvd will, I suppose, also need to
run on box (2) to work with machines on the wireless subnet. That part works too, but how do I set up radvd on that box to advertise the route
to the wireless subnet on the Ethernet subnet? I can only get it to
advertise itself as a default route, which is clearly wrong.

No. Router advertisements are designed to configure end-hosts only (give
them a static route and a prefix to perform stateless autoconfig in).
They do not exchange routing information between routers, in fact Linux
kernels with forwarding enabled ignore incoming router advertisements
completely.

Which means you have to add a static route on (1) to (2) for your
wireless subnet and a static default route on (2) towards (1). Or use
one of the real routing daemons (e.g. OSPFv3 or RIPng in the Quagga
package).

Bernhard


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