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OpenBSD IPv6 problem
On Wed, 7 Mar 2001, Robert Elz wrote:
> | the problem we see in "A B 127" (or 64) is ambiguity.
> Actually, in that one particular case (127), there should be none. With
> a shorter subnet mask there would be for sure (for anyone who doesn't
> see this, imagine 3ffe:9000::8/125 - configured with
> 3ffe:9000::9 -> 3ffe:9000::A
> and then ask yourself what you do with a packet addressed to 3ffe:9000::B)
> But where the mask is 127, there are only two possible addresses, mine
> and his - I'm not sending packets out at all if the address is mine
> (unless I like to implement that as a connectivity test and loop
> them through the peer) - in the other case, the address is his, and
> sending it to him (the peer) is clearly correct, whatever reasoning
> gets you to send it that way.
> Given that people want to be able to configure things this way
> (it suits their sense of aesthetics) and that it should do no
> real harm, I'd probably allow it - and then just treat it internally
> as if the prefixlen were 128 (but keep the /127 to return when
> requested so people don't get confused).
Well, it's that way we used to work for IPv4. For reasons of management,
we alway use 'numbered' interfaces.
For that, we have a a number of 'class C's, we divide into 64 '/30'
subnets, and each link is assign one of these pairs. Router loopbacks get
So, as I considered the prefixlen the IPv6 equivalent of the IPv4
'netmasks' (I hope I am correct about this), this translates into a single
'network' (3ffe:80b0:1001:ff::/64) I can divide into a -very very large-
number of /127 subnets I assign to the interfaces (in this case, a
Somebody any idea if this should be done differently in IPv6?
OK. There are some other options:
- Use the 'link-private' IP-address.
- Set up an IP-address on the loopback; and set up static routes for these
'lookbacks' on the routers.
(Or actually run OSPF or RIP between the routers).
(Hmm. Sounds like a good idea!).
Any more ideas or comments?
Cheerio! Kr. Bonne.
KB905-RIPE Belgacom IP networking
(c=be,a=rtt,p=belgacomgroup,s=Bonne,g=Kristoff) Internet, IP and IP/VPN
[email protected] Faxbox : +32 2 2435122