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Many cable modems have an LED labeled Cable or Data. Often, this LED flashes or blinks even when your PC is idle or turned off. Legitimate network data (most often DHCP and ARP traffic) is generated by Comcast, causing this behavior. This traffic should not be cause for worry, and should not affect your bandwidth.

To add, any given make / model number of a modem's particular firmware load can and could be coded to make that indicator light blink continuously regardless of the presence of or the absence of any traffic.

thanks to oldTDNickell5 See Profile

Definitions of terms: DHCP & ARP

DHCP: Dynamic Host Configuration Protocol. A protocol for assigning dynamic IP addresses to devices on a network.

ARP: Address Resolution Protocol. Its a protocol that allows the OS to associate an ip address (layer 3) with an ethernet MAC address (layer 2).

*This FAQ is based on user knowledge from a volunteer core of BroadbandReports' members. This FAQ in no way constitutes official information from Comcast or any of its affiliates.

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by Big_D See Profile edited by EG See Profile
last modified: 2013-04-18 14:17:38