VOIP with a linksys PAP2

[Kevin J. Cummings]

THUFIR HAWAT wrote:
> On 6/13/05, Kevin J. Cummings <cummings at kjchome.homeip.net> wrote:
> ...
> 
>>eth1 is neither UP, nor has any IP address information  (no IPADDR, no
>>NETMASK, no BROADCAST) so TCP/IP will not work over it.  Furthermore,
>>regardless of what may be attached to the network it is plugged into,
>>none of your routing referes to it (probably a side effect of not being
>>configured!  B^)
>>
> 
> 
> what's meant by "configured"?  I ask because I've used eth1 to connect
> to the internet.  after physically installing eth1 and rebooting I was
> presented with a menu and selected, IIRC, DHCP.

"Configured" is the actual assignment of the necessary configuration 
information necessary to make the device function in the desired 
environment.  (obscur enough for you?  B^)  In this case it would refer 
to the assignment of an IP address, a Netmask, and a Broadcast mask, and 
the appropriate changes made to the kernel routing table in order to 
accommodate the network interface into your working network.  *HOW* 
these attributes come to be assigned to the network interface may be 
because you selected DHCP, or because you entered them directly into a 
network configuration program.  Ultimately, it doesn't matter which, the 
end result is that they must be assigned.  In what you showed us with 
the output of the "ifconfig eth1" command, your eth1 interface is *NOT* 
configured at the time you ran the command.  It *must* ultimately be 
configured in order for it to work.  Period.

Furthermore, you need to keep your network interfaces straight.  In your 
original email, you mentioned that your internet interface was through 
eth0.  Above you say you've used eth1 to connect to the internet.  You 
can't start waffling the device names when you start presenting actual 
command output if you want to get the correct advice from the people 
helping you out!  Please!

> 
>>>thank you all so much for the help here :)
>>
>>If you have no devices on the eth1 network which will be DHCP servers,
>>you'll either have to run one on your Linux computer for it, or you'll
>>have to configure the TCP/IP staticly (ie, pick a private subnet network
>>address for it, and configure the network interface at boot time, and
>>configure all devices on that network so that they all have different
>>address in the same subnet.  Basic TCP/IP administration, this is what
>>we used to do before there was a DHCP standard!)
>>
>>I'm pretty sure that if you run system-config-network (as root) you'll
>>see that the eth1 interface is *NOT* active.  However, don't despair,
>>its the right tool to configure that interface for you!
>>
> 
> 
> 
> right, and "menu-->system tools-->network device control" also seems
> to bring this up.  isn't DHCP preferable because it's less fragile?
> 
> I don't understand "If you have no devices on the eth1 network which
> will be DHCP servers..." when on the eth1 network will be a hub and
> the VOIP PAP2.  is the PAP2 or the hub a DHCP server?  I'd think not,
> but don't know.

Read your owner's manual and be sure.  If it isn't, it probably is 
expecting to exist in an environment where a DHCP server is available to 
it.  If that is the case, you'll have to run one on your Linux computer 
which will serve addresses out to clients on the eth1 network so that 
they can work, and your Linux computer can forward their TCP stuff off 
to your internet service when necessary.  That means at least turning on 
IP forwarding in your Linux kernel, and possibly doing either NAT on 
your computer, or turning it from a router into some kind of a bridge so 
that the eth1 devices can communicate on the internet [my personal 
opinion is that a seperate routed network is easier to configure and 
administer, but, I could be wrong, and often am!]

 From my experience, I originally set my own Linux computer up as the 
firewall/router/NAT for my home network which includes 4 M$-Windows 
machines for the wife and kids.  The Cable modem is connected to one of 
my ethernet cards, the home network was connected to the second, and my 
machine performed IP forwarding and NATing for the internal network.  I 
know how it works, and I've been doing it for almost 10 years now (OK, I 
started with a SL/IP dial-up line before I got the cable modem).  Just a 
couple of months ago I inserted a Linksys 802.11g router after the cable 
modem, and added my computer to the internal network.  That means the 
Linksys router is now doing DHCP for the house network instead of my 
Linux computer.  The end result is that the *rest* of the computers on 
my home network didn't really see any difference in their network 
configuration!  The Linksys does everything for them that my computer 
used to do.  (OK, I'm still the SAMBA master, but that's another story).

> thanks,

You're very welcome!  Good Luck!

-- 
Kevin J. Cummings
kjchome at rcn.com
cummings at kjchome.homeip.net
cummings at kjc386.framingham.ma.us