seeing only ARP traffic ...

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this question relates more to networking than to the Linux OS, but I may be able to troubleshoot (or somehow probe) these issues using Linux.
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One day I noticed that I only saw ARP traffic from my modem. My ISP (leasing lines from Verizon) keeps telling me that they don't know what I am talking about that if I run tcpdump/wireshark right on the modem, I should see all traffic in the network, not just ARP traffic and the traffic from/to my address.
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Why would that be?
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Thank you
lbrtchx

lbrt wrote:
> this question relates more to networking than to the Linux OS, but I
> may be able to troubleshoot (or somehow probe) these issues using Linux.

> One day I noticed that I only saw ARP traffic from my modem. My ISP
> (leasing lines from Verizon) keeps telling me that they don't know what
> I am talking about that if I run tcpdump/wireshark right on the modem,
> I should see all traffic in the network, not just ARP traffic and the
> traffic from/to my address.

> Why would that be?

1. Is your modem the endpoint for your PPP connection? Or is it just a
device for translating between ethernet and cable, with the PPP connection
being terminated on your local Linux/Windows box?

Put it another way, do you run a PPP client on your Linux/Windows box?

2. When you ran tcpdump/wireshark on your modem, were you watching an
active interface?

Chris

On May 31, 5:17*am, lbrt chx _ gemale kom wrote:

> *this question relates more to networking than to the Linux OS, but I may be able to troubleshoot (or somehow probe) these issues using Linux.

> *One day I noticed that I only saw ARP traffic from my modem. My ISP (leasing lines from Verizon) keeps telling me that they don't know what I am talking about that if I run tcpdump/wireshark right on the modem, I should see all traffic in the network, not just ARP traffic and the traffic from/to my address.

> *Why would that be?

Likely you were looking at a switch port, so you saw only broadcast
traffic or traffic whose destination was unknown to the switch. Many
devices often described as "modems" or "routers" actually contain much
more functionality than their name would suggest and they may also
contain switches.

DS