Understanding multiple IPv6 interfaces under 8.0 (fwd)

[Dennis Glatting]

Thanks. Responses in-line.



On Mon, 14 Dec 2009, JASSAL Aman wrote:

> Hello Mr.Glatting,
>
> Not that I'm an IPv6 genius, but at first sight your problem seems to be a
> route-related. I've put comments in-line.
>
>
> Le Dim 13 d?cembre 2009 22:58, Dennis Glatting a ?crit :
>>
>>
>> Elmer# netstat -rn
>> Routing tables
>>
>>
>> Internet6:
>> Destination                       Gateway                       Flags
>> Netif Expire
>> ::/96                             ::1                           UGRS
>> lo0  => default                           fd7c:3f2b:e791:1::1
>> UGS        bce0
>> ::1                               ::1                           UH
>> lo0 ::ffff:0.0.0.0/96                 ::1                           UGRS
>> lo0 fd7c:3f2b:e791:1::/64             link#1                        U
>> bce0 fd7c:3f2b:e791:1::ac13:a0a        link#1                        UHS
>> lo0 fd7c:3f2b:e791:1:0:1:ac13:a0a     link#2                        UHS
>> lo0 fe80::/10                         ::1                           UGRS
>> lo0 fe80::%bce0/64                    link#1                        U
>> bce0 fe80::213:72ff:fe60:ac52%bce0     link#1                        UHS
>> lo0 fe80::%bce1/64                    link#2                        U
>> bce1 fe80::213:72ff:fe60:ac50%bce1     link#2                        UHS
>> lo0 fe80::%lo0/64                     link#3                        U
>> lo0 fe80::1%lo0                       link#3                        UHS
>> lo0 ff01:1::/32                       fe80::213:72ff:fe60:ac52%bce0 U
>> bce0 ff01:2::/32                       fd7c:3f2b:e791:1:0:1:ac13:a0a U
>> bce1 ff01:3::/32                       ::1                           U
>> lo0 ff02::/16                         ::1                           UGRS
>> lo0 ff02::%bce0/32                    fe80::213:72ff:fe60:ac52%bce0 U
>> bce0 ff02::%bce1/32                    fd7c:3f2b:e791:1:0:1:ac13:a0a U
>> bce1 ff02::%lo0/32                     ::1                           U
>> lo0
>>
>
> Hmm, the entry for fd7c:3f2b:e791:1:0:1:ac13:a0a looks suspect. I was 
> expecting bce1 rather than lo0, I suppose you were as well :) If I'm not 
> mistaken, the packets emanating from bce1 go to the loopback interface, 
> thus not really going out. You can try specifying the route manually 
> with "route add *your parameters*" or even set it in /etc/rc.conf so 
> that it's loaded at boot-time. There's no reason why among 2 physical 
> interfaces sharing the same fabric, one can ship packets out and the 
> other can't.
>

I was wondering about the route however I haven't figured out the trick to 
get what I want. For example:

Elmer# route delete -inet6 fd7c:3f2b:e791:1:0:1:ac13:a0a
delete host fd7c:3f2b:e791:1:0:1:ac13:a0a

Elmer# route add 
-inet6 fd7c:3f2b:e791:1:0:1:ac13:a0a/64 -iface bce1
route: writing to routing socket: File exists
add net fd7c:3f2b:e791:1:0:1:ac13:a0a/64: gateway bce1: route already in table

I did delete the lo0 route before I exected the above command. Also, I 
haven't been able to specify a higher metric (e.g., -metric 2). That is 
rejected too. However, I can say:

Elmer# route delete -inet6 fd7c:3f2b:e791:1:0:1:ac13:a0a
delete host fd7c:3f2b:e791:1:0:1:ac13:a0a

Elmer# route add -inet6 fd7c:3f2b:e791:1:0:1:ac13:a0a -iface bce1
add host fd7c:3f2b:e791:1:0:1:ac13:a0a: gateway bce1

Elmer# netstat -rn
(snip)
fd7c:3f2b:e791:1:0:1:ac13:a0a     00:13:72:60:ac:50             UHS        bce1

I don't think that is what I want. WHat I think I just said is "host X" is 
out that door, rather than route net. If, however, I say Docs is out that 
door, I get:

Elmer# route add -inet6 docs.dco.penx.com -iface bce1
add host docs.dco.penx.com: gateway bce1

Elmer# ping6 
docs.penx.com
PING6(56=40+8+8 bytes) fd7c:3f2b:e791:1:0:1:ac13:a0a --> fd7c:3f2b:e791:1::ac13:a15
ping6: sendmsg: Operation not permitted
ping6: wrote docs.dco.penx.com 16 chars, ret=-1


>>
>> Elmer's rc.config:
>>
>>
>> ipv6_enable="YES" ipv6_network_interfaces="bce0 bce1"
>> ipv6_ifconfig_bce0="FD7C:3F2B:E791:0001::0:172.19.10.10 prefixlen 64"
>> ipv6_ifconfig_bce1="FD7C:3F2B:E791:0001::1:172.19.10.10 prefixlen 64 mtu
>> 8192"
>> ipv6_defaultrouter="FD7C:3F2B:E791:0001::1"
>>
>
> Erm... You're using IPv4 addresses encapsulated in IPv6 ? I've never used
> this myself so I can't really comment, and I can't say if there aren't any
> sort of "interferences" with what you're trying to do.
>

I hope what I am specifying is to use the 32 bit IPv4 address as the last 
32 bits of the IPv6 address, at least that is how it works out 
numerically. My numbering scheme for fixed assets is the last 32 bits of 
the 128 bit IPv6 address is the same as its IPv4 address.


>>
>>
>> The router (cisco):
>>
>>
>> interface GigabitEthernet0/0 ipv6 address FD7C:3F2B:E791:1::1/64 ipv6
>> enable ipv6 nd prefix FD7C:3F2B:E791:1::/64 (etc)
>>
>
> Just a side-note, I'm not sure if it will be really useful to you, but you
> could give it a try if you want to. Have you tried using your Cisco router
> as a Router Advertisement Daemon ? That way, addresses would be built
> automatically and you could see how both interfaces react to such
> advertisements.
>
> I hope this helps.
>
> ------------
> Aman Jassal
>
> Wisdom comes from experience.
> Experience comes from a lack of wisdom.
>
>