Understanding ISP Bandwidth Charges and Physical Impact on Network Cabling

When ISP bandwidth charges come into play, it can lead to questions about the physical changes occurring in the network cabling to your home. This article explores how these charges work and what, if any, physical changes happen at the customer end. We will cover the differences between fiber and cable networks, and the specific upgrades needed for VDSL and DOCSIS 3.x users.

Optical Fiber vs. Cable-Modem Internet

For optical fiber, the cable itself remains unchanged regardless of the speed you are paying for. A 100Gbps connection today will use the same fiber as a 1Gbps connection. The speed limitations are set by the ISP at the end of the network, not at the fiber itself. This is because the fiber can support much higher speeds but the ISP must manage and allocate these resources.

For cable-modem Internet, the picture is slightly different. All speeds up to 1Gbps use the same end gear. For 10Gbps, the same end gear is used. To achieve speeds of 100Gbps, multiple 10Gbps end gear pieces can be combined into a single 100Gbps stream of data. This capability is currently technologically feasible.

Cable-Modem Internet Upgrades

For cable-modem Internet, upgrades may not require any physical changes to the underlying network infrastructure, such as head-ends, distribution hubs, or cable modems. However, there are cases where upgrades are necessary. When a fiber node serving a group of potentially hundreds of cable modems reaches a certain utilization threshold, the cable operator may need to allocate new ports on a cable modem termination system (CMTS) line card to handle the additional traffic.

DOCSIS 3.x is a specific case where the speed upgrade relies on using multiple bonded channels. For example, the bonding profile may change from 8 downstream channels and 4 upstream channels to 16 downstream channels and 4 upstream channels. In the head-end, the signals are sent into various timeslots and are reconstituted at the modem. Depending on the existing coaxial cabling, a new drop from the mainline tap may be required if RF ingress prevents achieving the necessary signal-to-noise ratio.

VDSL Speed Increases

VDSL (Very High Speed Digital Subscriber Line) upgrades require bonding multiple copper pairs, which may necessitate a technician accessing a remote terminal pedestal to manually combine and bond these pairs. This is necessary to achieve higher downstream and upstream speeds, as VDSL allows for bonding but in a different way than DOCSIS.

No Physical Changes to Home Cabling

It is important to note that there are no physical changes made to the cabling leading to your house when you pay for a higher bandwidth plan. The ISP simply reduces the amount of throttling that has been applied to your connection. This throttling can be managed and controlled within a network, either through a managed switch or a router, or by the ISP adjusting the settings on your modem.

When you upgrade your service, the ISP increases the allowable speeds that your modem can receive from their switches. This is done through hardware and software adjustments rather than physical changes to the cabling.