IPv6 autoconfiguration on a multihomed site

[Juan Rodriguez Hervella]

On Monday 29 September 2003 19:22, JINMEI Tatuya / 神明達哉 wrote:
> >>>>> On Mon, 29 Sep 2003 18:59:08 +0200,
> >>>>> Juan Rodriguez Hervella <jrh at it.uc3m.es> said:
> >
> > I've got two routers sending RAs on the same link, so the
> > host is configured with two IPv6 prefix on the same NIC.
> >
> > Watching the routing table I only see one default IPv6 route.
> >
> > When I try to ping the global IPv6 address of one router, if
> > I'm lucky and the router is the same router which I've got
> > installed on the default route, it will answer.
> >
> > The problem is that the host doesn't seem to realize that
> > it is on two links at the same time, so it always sends packets to the
> > default router....
> >
> > For example, if there's only one RA, the autoconfiguration process
> > ends up with a link-route like this:
> >
> > 2001:720:410:1001::/64            link#2                        UC       
> > fxp0
> >
> > On the other hand, when there are 2 RAs on the same link, this
> > route doesn't exist !
>
> I don't quite understand the situation...could you depict the network
> configuration with concrete prefixes/addresses, and describe the
> concrete problem (if it's a problem) with exact output of some
> commands (such as netstat, ifconfig, etc)?
>

Well, attached I depict the topology plus "ifconfig" and
"netstat -rn" outputs.

[ time to see the topology ]

After seeing the topology (uh Im a bit asleep)...
the situation is quite simple, 2 routers (site exit routers),
giving access to the internet using different ISPs. There is
only 1 link, so the host only have 1 NIC. 

The problem is that I can ping one of the routers, though
both the host and the router belong to the same network.
I guess the packets are always forwarded to the default
router, and I think that's not the expected behaviour, right ?

Cheers.

PS: I really love FreeBSD :)
-- 
JFRH
-------------- next part --------------
(Im really keen on ASCI art)
(of course, Im kidding)



                  Host
                    X 
                    X 
       XXXXXXXXXXXXXXXXXXXXXXX <-- wired link 
                  X
                  X
		Switch 3Com
                 X       X
		 X       X
		X         X
               X           X
          Router1         Router2
            X		    X
	    X		    X
	    X		    X
	   ISP1		   ISP2	


ISP1 delegated prefix: 2001:720:410:1000::/60
ISP2 delegated prefix: 2001:800:40:2470::/60

RA of Router1: 2001:720:410:100b::/64
RA of Router2: 2001:800:40:2471::/64


=>>>>> Output of "ifconfig"

jrh at pepitogrillo:~$ ifconfig
rl0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
        inet 163.117.140.44 netmask 0xffffff00 broadcast 163.117.140.255
        inet6 fe80::2c0:26ff:fea3:5df6%rl0 prefixlen 64 scopeid 0x1
        ether 00:c0:26:a3:5d:f6
        media: Ethernet autoselect (100baseTX <full-duplex>)
        status: active
rl1: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
        inet6 fe80::2c0:26ff:fea3:7d19%rl1 prefixlen 64 scopeid 0x2
        inet6 2001:800:40:2471:2c0:26ff:fea3:7d19 prefixlen 64 autoconf
        inet6 2001:720:410:100b:2c0:26ff:fea3:7d19 prefixlen 64 autoconf
        ether 00:c0:26:a3:7d:19
        media: Ethernet autoselect (100baseTX)
        status: active
[snipped]

The NIC I'm talking about is rl1, I use rl0 (IPv4) for
configuration purposes but I plan to remove IPv4 on the
short term.

=>>>>> Output of "netstat -rn":

jrh at pepitogrillo:~$ netstat -rn
Routing tables

Internet:
Destination        Gateway            Flags    Refs      Use  Netif Expire
default            163.117.140.2      UGSc        1        2    rl0
127.0.0.1          127.0.0.1          UH          0      220    lo0
163.117.140/24     link#1             UC          2        0    rl0
163.117.140.2      00:02:1b:f4:01:13  UHLW        2        0    rl0   1200
163.117.140.166    00:90:27:86:09:3d  UHLW        0      377    rl0   1060

Internet6:
Destination                       Gateway                       Flags      Netif Expire
default                           fe80::20b:5fff:fe77:dcc0%rl1  UGc         rl1
::1                               ::1                           UH          lo0
2001:720:410:100b:2c0:26ff:fea3:7d19 00:c0:26:a3:7d:19             UHL         lo0
2001:800:40:2471:2c0:26ff:fea3:7d19 00:c0:26:a3:7d:19             UHL         lo0
fe80::%rl0/64                     link#1                        UC          rl0
fe80::2c0:26ff:fea3:5df6%rl0      00:c0:26:a3:5d:f6             UHL         lo0
fe80::%rl1/64                     link#2                        UC          rl1
fe80::20b:5fff:fe77:dcc0%rl1      00:0b:5f:77:dc:c0             UHLW        rl1
fe80::20b:5fff:fe77:de61%rl1      00:0b:5f:77:de:61             UHLW        rl1
fe80::2c0:26ff:fea3:7d19%rl1      00:c0:26:a3:7d:19             UHL         lo0
fe80::%lo0/64                     fe80::1%lo0                   Uc          lo0
fe80::1%lo0                       link#8                        UHL         lo0
ff01::%rl0/32                     link#1                        UC          rl0
ff01::%rl1/32                     link#2                        UC          rl1
ff01::%lo0/32                     ::1                           UC          lo0
ff02::%rl0/32                     link#1                        UC          rl0
ff02::%rl1/32                     link#2                        UC          rl1
ff02::%lo0/32                     ::1                           UC          lo0
jrh at pepitogrillo:~$