[K12OSN] cable connection - direct to server

Les Mikesell lesmikesell at gmail.com
Wed Apr 7 16:38:39 UTC 2010

On 4/7/2010 10:29 AM, Barry Cisna wrote:
> Hello All,
> Thanks for all the suggestions. What I have tried:
> 1) Cloned MAC address of HFC/(cable mac) modem to server eth1, no luck.
> 2) Cloned MAC address of eth1 k12ltsp server to Linksys router router
> obtains ip address as expected from sb5120.
> 3) Made sure arp cache is cleared( This happens when eth1 is
> deactivated).
> One thing I noticed that is odd is,when the eth1 cat5 wire is plugged
> into modem the activity light is unlit. After activating the eth1 and
> goes through the trying to obtain IP address gyrations,and fails,the
> modem activity light stays lit. It appears at this point the SB5120
> modem is hanged.
> Of course I do not have a spare/different modem to try with. The
> connection is rock solid with the Linksys modem attached,though.
> As I stated before the server always throws different errors each time
> after trying to obtain an ip.
> This a 3 year old modem and design wise I'm guessing 6-7 years old.

If you are interested in debugging, you might try doing a wireshark 
capture of the DHCP request/response from the router and server to see 
what is different.  The easy way to do this would be to insert an old 
hub (that bridges all the ports) in the connection and use a different 
machine (so the interface is already active) to do the capture.  If you 
have thrown out all your hubs, you can do the same with a managed switch 
that lets one port monitor another.

   Les Mikesell
    lesmikesell at gmail.com

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