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MAC address didn't change



 
 
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  #1  
Old July 18th 03, 03:20 AM
news
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Default MAC address didn't change

I swapped out my old RCA cable modem for the new Terayon cable modem with
Comcast today. The MAC address seen from my Linksys router's status page
still displays the old MAC address. I turned off the router when connecting
the new modem. Everything is working but I expected to see a different
address. How does Comcast assign the address? There is a sticker attached
to the device with a MAC address. I thought the MAC address is built into
the firmware of the device. Is there a way to force the router to refresh
the MAC address of the modem sitting in the WAN port?

--
kd


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  #2  
Old July 18th 03, 05:09 AM
$Bill
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user wrote:

Warren wrote:

The WAN MAC shown on the status page of your Linksys router is that of
the router, not the modem.




No, I see two MAC addresses on the Status page. One listed with the LAN
section and one listed with the WAN section.


Duh, a router has two MAC addresses so it can talk to the Lan side and
WAN side.

  #3  
Old July 18th 03, 05:27 AM
news
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"$Bill" wrote in message
...
user wrote:

Warren wrote:

The WAN MAC shown on the status page of your Linksys router is that of
the router, not the modem.




No, I see two MAC addresses on the Status page. One listed with the LAN
section and one listed with the WAN section.


Duh, a router has two MAC addresses so it can talk to the Lan side and
WAN side.


Is the WANs IP address which is assigned by the ISP stored in the cable
modem's firmware or the router's firmware. When I ping that address, am I
pinging the modem or the router?


  #4  
Old July 18th 03, 05:43 AM
$Bill
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news wrote:

"$Bill" wrote in message
...

user wrote:


Warren wrote:


The WAN MAC shown on the status page of your Linksys router is that of
the router, not the modem.




No, I see two MAC addresses on the Status page. One listed with the LAN
section and one listed with the WAN section.


Duh, a router has two MAC addresses so it can talk to the Lan side and
WAN side.



Is the WANs IP address which is assigned by the ISP stored in the cable
modem's firmware or the router's firmware. When I ping that address, am I
pinging the modem or the router?


I'm no expert on the workings of a cable modem, but the IP address
assigned by the ISP would basically get you to both the modem and
the router. It would become the router's IP address since the modem
really doesn't care about IP addresses TTBOMK. You'd be pinging
the router (through the modem).

  #5  
Old July 18th 03, 06:57 AM
news
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Default

[snip]

I'm no expert on the workings of a cable modem, but the IP address
assigned by the ISP would basically get you to both the modem and
the router. It would become the router's IP address since the modem
really doesn't care about IP addresses TTBOMK. You'd be pinging
the router (through the modem).


OK, its starting to make some sense. I was looking at the output of
ipconfig /all on one of my PCs. In the output is the MAC address of the NIC
on the machine. If connected the cable modem directly to the PC instead of
the router this wouldn't change the MAC address. And as you mentioned, a
ping of the assigned IP address would go through the modem to the NIC on the
PC because its the PCs NIC that contains the TCP/IP settings for the IP.


  #6  
Old July 31st 03, 02:34 AM
Mike Pockrus
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Are we talking MAC or IP??

The IP is actually assigned to the computer (or router in this case) not the
modem. You can have a static IP address for your computer through your
provider, swap the modem and still continue to use that original IP. As for
how long you'll have an IP.... with us it is refreshed every three hours or so,
but frequently is allowed to keep the same address for days or weeks.

Mike- Adelphia Field Technician
  #7  
Old July 31st 03, 03:40 AM
redhat_devel
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Default



Mike Pockrus wrote:
Are we talking MAC or IP??

The IP is actually assigned to the computer (or router in this case) not the
modem.


The modem obtains a private 10.x.x.x for managability. It gets its IP
from the CNR or NetID box at the aggregation sites.

The CPE(computer/router) gets a public routable IP.

You can have a static IP address for your computer through your
provider, swap the modem and still continue to use that original IP. As for
how long you'll have an IP.... with us it is refreshed every three hours or so,
but frequently is allowed to keep the same address for days or weeks.


On the Adelphia network, it can be longer, since the IP utilization from
CNR and/or NetID comes out on the 80%. Then the DCC requests more IP's
to be placed on the DHCP server(s). As long as the DHCP pool does not
fill up and more IP's are placed within the 80% mark, you can basically
"own" that DHCP address persay.


Mike- Adelphia Field Technician


--



"Windows: In a world without fences, who needs gates?"


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  #8  
Old July 31st 03, 04:05 AM
Warren
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"redhat_devel" wrote in message
...




Who knows what he wrote. There's an attachment to this message that has
a txt extension, but I'm not going to bother to check to make sure that
it is nothing but text before I open it.

--
Warren H.

==========
Disclaimer: My views reflect those of myself, and not my
employer, my friends, nor (as she often tells me) my wife.
Any resemblance to the views of anybody living or dead is
coincidental. No animals were hurt in the writing of this
response -- unless you count my dog who desperately wants
to go outside now.
Blatant Plug:
Support me at: http://www.holzemville.com/mall/




  #9  
Old July 31st 03, 11:47 AM
James Knott
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Default

Mike Pockrus wrote:

The IP is actually assigned to the computer (or router in this case) not
the modem.


Actually, it's assigned to the interface.

You can have a static IP address for your computer through your
provider, swap the modem and still continue to use that original IP. As

for
how long you'll have an IP.... with us it is refreshed every three hours

or so,
but frequently is allowed to keep the same address for days or weeks.


My dhcp lease is for 7 days, but I keep the same IP for months, until
something causes a change. i.e. network reconfiguration

--

Fundamentalism is fundamentally wrong.

To reply to this message, replace everything to the left of "@" with
james.knott.
 




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