Hello everybody,
First of all I hope I'm on a right forum to ask this question. I had my 1st cable connection today, before I've always had dsl. Everything works fine but I realized that the "cable activity" diod of the THG540 modem blinks like crazy even if do nothing on the net. I had a look at the network with tcpdump and I can see a LOT of ARP request of my ISP (Kabel Deutschland). Is this normal in the cable technology ? Since the APR packets are not routable, does it mean that I'm on a LAN of my ISP with other clients ?
Btw, I get an IP address by DHCP from the ISP and this IP is public and accessible from the net.
Thanks for your help.
Regards,
Tex
Totally normal. Your modem is ultimately connected to a cable blade that will have 1 or more subnets configured on it. There may be a thousand people or more using services off that blade, but typically the number is 250 to 500. The arps are from the head end router looking for you or other subscribers. The connection attempts are usually from remote systems attempting to portscan, etc - same stuff as you'd see on DSL. The arps are on the broadcast which everyone sees. However, the application traffic between subscribers and the head end is unicast, so you shouldn't see any of that -- just the normal flow of broadcast traffic.
yep I see only the broadcasted arp requests, no answers cos there are unicated.
ok thanks for the explanation.
regards,
Tex.