[X-Unix] How to determine which network component is failing

Sun Jul 23 07:44:30 PDT 2006

On Jul 23, 2006, at 8:54 AM, Dennis Fazio wrote:

>
> On Jul 23, 2006, at 8:03 AM, Charles Howse wrote:
>
>> This morning, I was offline, and just by accident decided to try  
>> and release and renew the ip address using the web interface of  
>> the router.
>> BINGO!  Online again!
>>
>> Is this an indication that the router is not noticing that the  
>> lease has expired on my dhcp assigned ip address from the modem?   
>> Or is it an indication that the modem is not renewing it's ip  
>> address?  Or is it something else?
>>
>> Can I tell the router to release / renew the ip address from a  
>> shell script?
>
> I'm not familiar enough with things to say what your problem might  
> be from your description.
>
> But, you can verify if you got a good IP address in the network  
> preferences panel. There is a button there to also renew your DHCP  
> lease. Often turning airport off and on or disonnecting and  
> reconnecting the ethernet cable triggers things also. When the  
> connection is working, do a traceroute to get the IP of the cable  
> modem and the next upstream hop. Then you can progressively ping  
> through the path to see where things are failing (LAN or cable  
> modem/upstream path).

Hmmm...
[charles at larry:~]$ traceroute -P ICMP charter.net
traceroute to charter.net (64.192.190.12), 64 hops max, 60 byte packets
1  10.162.0.1 (10.162.0.1)  9.527 ms  6.892 ms  9.817 ms
2  24-159-70-1.dhcp.jcsn.tn.charter.com (24.159.70.1)  8.235 ms   
5.684 ms  6.037 ms
3  172.21.28.102 (172.21.28.102)  7.518 ms  9.843 ms  6.499 ms
4  24-159-64-2.static.jcsn.tn.charter.com (24.159.64.2)  7.095 ms   
5.891 ms  5.571 ms
5  24-159-64-194.static.jcsn.tn.charter.com (24.159.64.194)  18.533  
ms  15.586 ms  14.195 ms
6  24-159-64-41.static.jcsn.tn.charter.com (24.159.64.41)  13.611 ms   
14.333 ms  13.454 ms
7  nsvltn1wcx010-pos-4-0-wcg.net (64.200.71.13)  13.760 ms  15.220  
ms  13.982 ms
8  cncnoh1wcx010-pos9-0-wcg.net (64.200.240.238)  19.386 ms  19.584  
ms  20.741 ms
9  bflony1wcx010-pos-9-0-wcg.net (64.200.249.81)  41.534 ms  44.325  
ms  41.017 ms
10  albyny1wcx010-pos-5-0-wcg.net (64.200.68.221)  40.459 ms  36.872  
ms  37.777 ms
11  albyny1wcx010-pos6-0-wcg.net (64.200.87.229)  46.237 ms  45.016  
ms  43.975 ms
12  nycmny2wcx1-pos6-0.wcg.net (64.200.68.53)  42.453 ms  42.129 ms   
41.600 ms
13  nycmny2wcx1-charter-12-1.wcg.net (64.200.81.218)  54.802 ms   
53.621 ms  51.565 ms
14  64-192-190-12.wcg.net (64.192.190.12)  51.627 ms  51.018 ms   
51.482 ms

The ip address of the modem, as shown on the status page of the  
router, doesn't show up above.

I have been working with curl to get the ip address, but it returns a  
real mess:
[charles at larry:~]$ curl -s http://192.168.254.254/Status_Router.htm
<HTML><HEAD><TITLE>Setup</TITLE><META http-equiv=Content-Language  
content=en-us><META http-equiv=Content-Type content='text/html;  
charset=iso-8859-1'><style fprolloverstyle>A:hover {color: #00FFFF} 
BODY{FONT: 10pt Arial,Helvetica,sans-serif; COLOR: black}TH {FONT:  
bold 10pt Arial,Helvetica,sans-serif; COLOR: white;}TABLE {FONT: 10pt  
Arial,Helvetica,sans-serif; COLOR: black; BORDER: Medium White None;  
border-collapse: collapse}TD{font-size: 8pt; font-family: Arial,  
Helvetica, sans-serif}.num{FONT: 8pt Courier,serif;}.bar{background- 
color:white;}A{text-decoration: none;}A:link{color: #ffffff;}A:visited 
{color: #ffffff;}A:hover {color: #00FFFF;}.small A:link{color:  
#B5B5E6;}.small A:visited{color: #B5B5E6;}.small A:hover {color:  
#00FFFF;}</style><SCRIPT language=JavaScript>function pppoeAction(F,I) 
{   F.pppoeAct.value = I;   F.submit();}function DHCPAct(F,I) 
{      F.dhcpAction.value = I; F.submit();}function showAlert(){alert 
('');}</SCRIPT>...
[snip a ton of html garbage]

It's in there, but pulling it out in a shell script will be very  
problematic.

>
> You can also just assign static addresses to your computers if you  
> think DHCP is being problematic. That will isolate whether the  
> problem is connectivity/routing or address assignment. I find  
> BwanaDik is a good tool for determining if you have good internal  
> and external addresses set.

I use static addresses on all the lan computers.  The dhcp server on  
the router is turned off.
One issue might be that the modem's lan address is 192.168.100.1, and  
the default address for the router is 192.168.1.1.  I have changed  
that to 192.168.254.254, and set the computers to 192.168.254.*/ 
255.255.255.0.
Do you think it would help anything to set the router to  
192.168.100.254, and the computers to 192.168.100.*/255.255.255.0?
Then everything would be on the same subnet.
That will be easy to do, I will change it while I wait for a reply  
from the list, and see what happens.

I have the iStat nano widget, which shows my internal/external ip  
addresses.

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