Re: Out of work Rocket Scientist..

Bill Woodland (
Thu, 02 Apr 1998 14:13:58 -0600

Once again, the anser to this is that CU-SeeME will NOT work thru a proxy
server, nor will it work with NAT (see below) like this.

I'm not an expert at proxies or NAT, so this may not be TOTALLY accurate,
but you should get the picture:

What you have here is probably what's referred to as Network Address
Translation (NAT), and CU just won't work with this, because the IP address
of the machine you're using is imbedded into the data packets so that the
reflector knows what address to send the data back to (how do you say this
without a dangling participle?).

The IP address from your email message is, which is probably
your ISP's router. Your ISP has given you a fake IP address, and when you
send data thru your Ascend, it goes into their system and the IP address in
the HEADER of the packets is replaced with the address of their router.
This way MOST TCP applications will know where to return the data (to their
router), after which their router will do the reverse address translation
and return the data back to your Ascend. The problem is that REFLECTORS
use the IP address imbedded inside the data, and are trying to send video
back to, which doesn't actually exist.

Your machine needs to have a REAL IP address of its own, not a pretend IP
address like You need your ISP to give you what's called
a subnet of 4-16 IP addresses, assign one to the Ascend, and one to each
machine connected to it.

At 06:19 PM 4/2/98 -0500, Monte Freeman wrote:
>Ok, so I'm neither out of work nor a rocket scientist... :)
>But, CU-SeeMe shouldn't be rocket science either so I've got to be missing
>something simple.
>Here's how my system setup looks:
>Pentium clone machine w/64 megs of ram running Win 95.
>3-Com PCI Ethernet card
>Ascend Pipeline 50 connected to an ISDN line
>Internet service in Atlanta Georgia through
>They do NAT (Network Address Translation) for their ISDN customers. I get a
>DHCP-assigned IP address each time I connect to them.
>The ip address of my PC is The ip address of the Ascend is
>I *CAN* telnet, ftp, ping, web surf through this connection. Works great
>other than being a little slow somtimes.
>I *CAN NOT* get CU-SeeMe wo work through the ISDN connection. I have two
>different versions of the free Cornell version, and I have the White Pine
>one. None of them will connect to a server through the ISDN connection,
>however all three versions will connect to the reflector I set up on a Sun
>Sparc 2 on the other side of the room connected to the same ethernet hub.

In THIS case, the IP addresses are all on the same side of your Ascend, so
there's no address translation being done at all. You could setup a
network of 250 computers and send from any one of them to any other, as
long as the data doesn't go thru your Ascend.

>No matter what server from the list in the White Pine (version 3.1 build 25 )
>implementation I pick, I get the message " No response from <server name>
>[ECU ID#:8293]". The free Cornell versions just say 'No response from
>Anyone see anything I listed here that might be causing these problems? I'm
>most happy to provide any other information needed, I'd just like to get
>this working. The tech support people at have been worthless
>in trying to figure this out. Cu-SeeMe is not a "Supported Application", but
>they "see no reason it shouldn't be working" whatever that means..
> Regards,
> Monte Freeman
> Atlanta, Georgia

Bill Woodland (Squeek ) PC questions only, please.
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