[CLUE-Tech] Cisco 678 Configuration

[Randy Arabie]

Hello fellow Linux enthusiasts.  I've been racking my brain over a Cisco 678 
DSL router configuration problelm for several days now.  This particular router 
worked fine on the Qwest network in Denver for 2+ years.

I thought setting it up here in Bellingham, WA would be a breeze.  I've got DSL 
with Qwest here, also. The network is DMT, just as it was in Denver.  

The router doesn't seem to be routing, sort of.  When I connect it to the phone 
line it trains and the wan0 port(s) link up with the upstream network.  
The "inside" eth0 is configured to the standard class C 192.168.1.1 with the 
internal DHCP server configured to dish out IP's.  And, NAT is enabled.  I've 
also enabled the telnet server so my ISP's techies could try and help me figure 
out why it won't work.

Using the serial management interface, from the cbos prompt I can ping and 
traceroute to public IP's out on the net.  And, the support folks at my ISP can 
telnet into the router from the outside.  IMO, this cofirms that there are no 
problems with the wan0 interface.

LAN hosts connected either directly to the router, or via a hub get assigned 
IP's with the appropriate gateway and DNS servers.  These hosts can ping the 
router's eth0 interface (192.168.1.1) and each other.  However, they cannot 
telnet to the router's eth0 interface.  And AFAICT, they can't ping anything 
past the router's eth0 interface.  Maybe the ping requests are getting out, but 
the replies aren't getting back.

Using the serial management interface, from the cbos prompt I cannot ping any 
of my LAN hosts.  I've run ethreal on my laptop and confirmed that no ping 
requests are comming from the router.  And, I've also captured the results of 
pinging the router from my laptop, along with other expriments.

Here's a link to the ethreal output file [tcpdump format]:
  
  http://www.arabie.org/pub/ethreal.out

The only questionable thing I've seen on the router is the arp table.  On a 
number of occaisions I've seen entries labeled as "invalid" and the MAC address 
for the entry doesn't match either my laptop or the router.  I've cleared the 
router's arp table, rebooted it, and tried again but the thing still won't 
work.  These entries appear when I try to telnet to hosts outside my LAN.  Or, 
when I try to telnet to the public IP assigned to the router's wan0-0 interface.

Here's a link to a transcript of my cbos session:

  http://www.arabie.org/pub/cisco678.txt

If you scan down to my "show nat" and "show arp" commands, those correspond to 
times when I've tried to telnet out from an internal host.

I'm dropping the router off with my ISP, and I think they are gonna have a 
loaner for me.  Their techie is going to have a look at it.  So far, they don't 
know what the problem is.

I'm stumped.  It has to be some sort of config problem.  I'm ready to flash the 
thing with a new cbos image.  It's running v2.4.3, and I think the current it 
2.4.6.  However, I'm not sure how to do that. Since I can't even connect via 
telnet, I doubt tftp would work.  How would I get the image onto it?

Maybe one of you networking guru's will have an idea...

-- 
Allons Rouler!

Randy
http://www.arabie.org/