Every cable modem works off multiple channels. Each channel is able to download at 38 Mbps. Thus a 4channel modem is able to do 152Mbps max, 8ch 304Mbps 16ch at 608 Mbps and so on.

This is actually how Comcast is able to separate the private WiFi and the "xfinitywifi" from one another with out interrupting the other. Remember those threads where Comcast turned on the XfinityWifi signal with out the owner's knowledge. And we all talked about security, and bandwidth being an issue and what not. Well the gateways that Comcast rents out are using the first 8 channels for the consumers private wifi, then the next 8 for the public xfinitywifi. Technically the gateway has the ability to do 24 channels, but it's on the Comcast end it's only putting out 16 channels... for now at least. In some markets they are at 24 and testing Gb speeds.

[Link: en.wikipedia.org]

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