Freebsd 5.1 <-> Win XP Networking problems

[Danny MacMillan]

On Wed, Jul 14, 2004 at 03:41:04AM -0600, Matthew Seaman wrote:
> On Tue, Jul 13, 2004 at 02:32:46PM -0700, Darren Pilgrim wrote:
> 
> > > 	ifconfig_ed0="inet 192.168.1.0/24  netmask 255.255.0.0"
> > > 	ifconfig_vr0="inet 192.168.0.0/24  netmask 255.255.0.0"
> > 
> > 192.168.1.0/24 and 192.168.0.0/24 are blocks of addresses in CIDR notation,
> > not the actual addresses to be fed to ifconfig.  You need to pick addresses
> > within the netblock to use for myserver and all the other machines on your
> > network.  Since myserver can reach the internet just fine, you should keep
> > the IP address for vr0 the same, just lengthen the netmask to allow the use
> > of 192.168.1.0/24 on the LAN.
> 
> ifconfig(8) understands CIDR notation just fine, although it's not
> usual to configure an interface using the '.0' /network/ address.  Look
> on it as a third alternate way of specifying the netmask, so that the
> following three examples are equivalent:
> 
> 	ifconfig fxp0 inet 192.168.123.74/29
>         ifconfig fxp0 inet 192.168.123.74 netmask 0xfffffff8
>         ifconfig fxp0 inet 192.168.123.74 netmask 255.255.255.248
> 
> Those correspond to the slightly contrived example of the /29 network
> starting with network address 192.168.123.72 and running up to the
> broadcast address 192.168.123.79
> 
> Note: you can give a broadcast address on the ifconfig command line,
> but usually it's not necessary as a standard value will be calculated
> from any ip number forming part of that network and from the netmask.
> However you can't in general use ip address + broadcast to do the
> converse, as there isn't necessarily a unique solution.

I apologize for asking this question here, but I've googled and read
arp(4) and arp(1) and nothing I can see gives a clear answer (at least
clear to me).  It is related to this thread.

Is it the subnet mask that lets my computer know that for an IP address
located external to my network it should send the packet to the router
(using the router's MAC address) instead of arp-ing for the MAC address
of the target node?  This is the only way I can see that this would
make sense, as arp -a doesn't seem to return the MAC addresses of boxes
on the other side of my router under any circumstances.  I read a
document online that suggested that a router would recursively ARP for
a non-local MAC address but this seems insane and highly improbable to
me.  More likely is that my computer, knowing that an IP address is
not local by examining the network address, would choose a route from
its routing table, arp for that router's MAC address, and send the
packet thither.  But is that what actually happens?

Pointers to documentation explaining this accepted with my thanks.

--
Danny MacMillan