On Sun, Aug 17, 2003 at 06:31:38AM +0800, John Summerfield wrote:

| On Sat, 16 Aug 2003, Phil Howard wrote:
|
| > I'm running Linux/390 (2.4.17) under Hercules (2.17.1) under Linux (2.4.21)
| > on x86, and noticed that the encapsulation between host and guest systems
| > for the CTC via TUN interface is different:
| >
| > On the host side:
| >
| > tun0      Link encap:Point-to-Point Protocol
| >           inet addr:192.168.10.1  P-t-P:192.168.10.2  Mask:255.255.255.255
| >           UP POINTOPOINT RUNNING  MTU:1500  Metric:1
| >           RX packets:45 errors:0 dropped:0 overruns:0 frame:0
| >           TX packets:55 errors:0 dropped:0 overruns:0 carrier:0
| >           collisions:0 txqueuelen:10
| >           RX bytes:6067 (5.9 Kb)  TX bytes:5780 (5.6 Kb)
| >
| > On the guest side (note the P-t-P address, too):
| >
| > ctc0      Link encap:Serial Line IP
| >           inet addr:192.168.10.2  P-t-P:192.168.10.2  Mask:255.255.255.252
| >           UP POINTOPOINT RUNNING NOARP  MTU:1500  Metric:1
| >           RX packets:49 errors:0 dropped:0 overruns:0 frame:0
| >           TX packets:40 errors:0 dropped:0 overruns:0 carrier:0
| >           collisions:0 txqueuelen:100
| >           RX bytes:5460 (5.3 KiB)  TX bytes:5471 (5.3 KiB)
| >
| > How is that supposed to work?
|
| With those IP addresses, does it?

Yes, it is working fine.  The ifconfig output was obtained via an ssh
session to the Linux/390 system running under Hercules right then.


| I IPLed my system to take a look and for once tun0 didn't come up
| cleanly so I had to configure it cleanly.
|
| Now I have different encapsulation _and_ different multicast and
| different MTU.

I'm thinking the PPP code might have a default capability that if it does
not receive any negotiations, it falls back to a "raw" IP tranfer mode,
which is basically SLIP.

--
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| Phil Howard KA9WGN       | http://linuxhomepage.com/      http://ham.org/ |
| (first name) at ipal.net | http://phil.ipal.org/   http://ka9wgn.ham.org/ |
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