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From: nigel@znet.net.au (Nigel Gorry)
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: Two devices with same IP
Date: Sun, 24 Nov 1996 13:59:45
Organization: Zed.Net Internet Services
Lines: 26
Message-ID: <nigel.26.000DFF56@znet.net.au>
References: <56ltqk$nhv@csugrad.cs.vt.edu> <56lvvc$62f$1@gail.ripco.com> <577usn$15g@anorak.coverform.lan>
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In article <577usn$15g@anorak.coverform.lan> brian@anorak.coverform.lan (Brian Somers) writes:
>>>If the above machine sends a packet to 203.61.202.{16-19,21-22} (assuming
>>>that 203.61.202.16 is your net address and 203.61.202.23 is your *real*
>>>broadcast address, how does your kernel know which of ed0 and tun0 to send
>>>the packet ?
>:
>: because tun0 is a Point-to-Point link, so it will only send packets over tun0
>: that are destined for the remote end.
>:
>: Therefore my routing table is such:
>:
>: 203.61.202.16/28 --> ed0
>: 203.61.202.1 --> tun0
>: default --> 203.61.202.1 (via tun0)
>Ah, well that's my original point. Your tun0 device (IMO) should have
>a netmask of 0xffffffff. A looser netmask says that I can reach
>additional machines directly down that interface - which doesn't
>really make sense down a point-to-point type interface.
I think the netmask is irrelevant on a Point-to-Point link. I used to use
0xffffffff, but when I reconfigured I got lazy and just left it at the default
0xffffff00, and it seemed to make absolutely no difference to the routing
table. I know that it should make a difference, and on dedicated routers it
does, but not in FreeBSD.