Re: [Plug] ppp and ethernet with SuSE

["LeRoy D. Cressy" <ldc@netaxs.com>]

Hi All,

In all of the discussion I don't remember anyone posting the results of
running ifconfig to see what both eth0 and ppp0 are doing.

for instance:

 ifconfig 
eth0      Link encap:Ethernet  HWaddr 00:20:18:2C:90:8E  
          inet addr:192.168.1.1  Bcast:192.168.1.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:22 errors:0 dropped:0 overruns:0 frame:0
          TX packets:9 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:100 
          Interrupt:5 Base address:0xfce0 

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          UP LOOPBACK RUNNING  MTU:3924  Metric:1
          RX packets:414 errors:0 dropped:0 overruns:0 frame:0
          TX packets:414 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 

ppp0      Link encap:Point-to-Point Protocol  
          inet addr:207.106.60.15  P-t-P:207.106.60.1 
Mask:255.255.255.255
          UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1500  Metric:1
          RX packets:2005 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1929 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:10 

Also looking at the kernel routing table can be a help:

207.106.60.1    *               255.255.255.255 UH    0      0        0
ppp0
localnet        *               255.255.255.0   U     0      0        0
eth0
default         207.106.60.1    0.0.0.0         UG    0      0        0
ppp0

And finally, look at your /etc/ppp/options file to see if your pppd is
breaking your ethernet connection.  Now when you connect to the
internet, your isp connection should become the gateway for the box
connected to the internet.  Also, the boxes on the ethernet that are
connected to the box that has the modem should be set up with the
gateway being the box with the modem.  I hope that this makes sense :-)

It would be a tremendous help for you to read the documentation on pppd
and all of the networking stuff.  I have had problems in the past with
various distribution ppp connection schemes.  So I wrote my own scripts
to make the system behave like I wanted it to.  And if you are running a
home network with a Linux box connected to the internet like me, I have
found tremendous knowledge to be gleaned from the HOWTO docs and the
individual package documentation.  Not the most interesting read, but
very informative.

Suggested Reading:

/usr/doc/ppp/*
/usr/doc/HOWTO/PPP-HOWTO.gz
/usr/doc/HOWTO/Networking-Overview-HOWTO.gz
/usr/doc/HOWTO/NET-3-HOWTO.gz
/usr/doc/HOWTO/Modem-HOWTO.gz
/usr/doc/HOWTO/ISP-Hookup-HOWTO.gz

Though this is not a simple answer to the specific question about pppd
breaking eth0, I think that looking at the routing table, netstat and
taking a close look at the networking configuration files would help 
resolv the problem.


Hugh Brock wrote:
> 
> Martin DiViaio wrote:
> >
> > What happens when you bring up eth0 after connecting with ppp?
> 
> Good question -- hadn't thought of that. I just tried it, and bringing
> up eth0 seems to disable the ppp connection although it doesn't actually
> knock me offline. Also eth0 does not work when I bring it up that way --
> it will show up and configured, but I can't telnet out to anything,
> which I can when I bring it up without ppp.
> 
> This is getting wierder and wierder; at first I thought it was just a
> network config issue, but now I'm beginning to think it really is a
> driver problem with this combo modem... works fine under NT, of course,
> but then there's a company driver for that... sigh...
> 
> Another thing I've noticed, and this may be germane: When I connect with
> ppp, /proc/interrupts shows a serial device on irq5. When I bring eth0
> up, it also shows irq5 and ioport 0x300. There's no indication of what
> io port the serial device is using, except that pcnet_cs has 2f8 to 2ff
> and (on a separate line) 300 to 31f. I believe the card also uses the
> same interrupt for both functions under NT, although I couldn't swear to
> it. But I wonder if that isn't part of the problem...
> 
> Any inspiration?
> 
> Thanks,
> --Hugh
> 
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LeRoy D. Cressy     	 /\_/\		ldc@netaxs.com
Computer Consulting 	( o.o )		Phone (215) 535-4037
		 	 > ^ <		Fax   (215) 535-4285



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