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-   -   DHCP & Cable Modem (https://www.linuxquestions.org/questions/linux-networking-3/dhcp-and-cable-modem-79523/)

raypen 08-06-2003 10:28 AM

DHCP & Cable Modem
 
Having become thoroughly acquainted (and thus confused) by
my cable modem/network setup, I have a nagging question.

My dhcpcd-eth0.info file contains a reference:

DHCPSHADDR=00:0B:5F:EE:86:A8

which is of course a MAC address for some part of cable
head end setup. Unfortunately, this doesn't match the MAC
address of my assigned gateway (the public address of the
cable head end). I can only use ARP to find the MAC of
the public address; there are no ARP entries associated
with the private address even though I know what it is from
traceroute.

Can anyone tell me which piece of hardware this address
is supposed to represent? Is it the MAC address of the
DHCP server (DHCPSID)?

TIA

Looking_Lost 08-06-2003 03:53 PM

Whats the mac address of your network card?

raypen 08-06-2003 04:50 PM

I'll show mine if you'll show me yours!

jkcunningham 08-06-2003 05:21 PM

Try doing 'ifconfig eth0'. My bet is its the same MAC address.

raypen 08-06-2003 09:16 PM

Actually, it is not. It is a MAC address of some part or counterpart
of the cable head end or ISP-side cable network.

Oddly enough, it differs from the MAC address of the gateway
(or public address of the UBR) only by the last hex digit twosome.

In other words, it looks like this:

DHCPSHADDR=00:0B:5F:EE:86:A8
Gateway IP=00:0B:5F:EE:86:D9

I've looked everywhere for a description of DHCPSHADDR, but
cannot find anything definitive.

It's not that important since everything works just fine, but
I hate to leave these little questions unanswered.

A good reference for cable network's and how they
are set up is:

http://homepage.ntlworld.com/robin.d...ips/index.html


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