[107043] in North American Network Operators' Group
Re: It's Ars Tech's turn to bang the IPv4 exhaustion drum
daemon@ATHENA.MIT.EDU (Iljitsch van Beijnum)
Thu Aug 21 04:10:40 2008
From: Iljitsch van Beijnum <iljitsch@muada.com>
To: Crist Clark <Crist.Clark@globalstar.com>
In-Reply-To: <48AC0F0D.8C45.0097.0@globalstar.com>
Date: Thu, 21 Aug 2008 10:09:58 +0200
Cc: nanog@nanog.org
Errors-To: nanog-bounces@nanog.org
On 20 aug 2008, at 21:33, Crist Clark wrote:
> No, that's my point. On a true point-to-point link, there is
> only one other address on the link. That's what point-to-point
> means.
> For example, on the IPv4 ends gif(4) tunnel in my previous message,
>
> gif0: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> metric 0 mtu 1280
> tunnel inet 24.6.175.101 --> 72.52.104.74
> inet6 fe80::200:24ff:feca:91b4%gif0 prefixlen 64 scopeid 0x7
> inet6 2001:470:1f04:2fc::2 --> 2001:470:1f04:2fc::1 prefixlen
> 128
Note that this interface doesn't _have_ any IPv4 addresses: the IPv4
addresses that you see are the tunnel endpoints.
However, the IPv6 addresses do what you say: there is a local one and
a remote one and they don't share a subnet. Obviously it's possible to
do this, but in my opinion, this is just an implementation variation,
not the natural state of point-to-point links. It makes much more
sense to have one set of behaviors that applies to all interfaces.
And what is a point-to-point link, anyway? In theory gigabit ethernet
is CSMA/CD, but I don't think anyone ever bothered to implement that,
in practice it's point-to-point on layer 1, but layer 2 is point-to-
multipoint...
