Virgin Media's Evolving Network

What is DOCSIS?

DOCSIS is a set of telecommunications standards that allow internet data to be transmitted over existing cable TV lines, particularly coaxial cables. Virgin Media uses this system to deliver broadband through its HFC network, which combines fibre-optic cables for most of the journey and switches to coaxial cables for the last stretch into homes.

Virgin Media has upgraded its network to DOCSIS 3.1, which supports download speeds up to 10 Gbps and upload speeds of 1 Gbps. This technology has enabled Virgin to offer ultra-fast broadband packages like Gig1, providing download speeds of up to 1130 Mbps. However, while DOCSIS 3.1 can handle impressive speeds, it introduces some limitations in terms of latency and upload capacity, especially for demanding applications like online gaming or content creation.

The Limitations of DOCSIS

Despite its high download speeds, DOCSIS technology struggles with latency and reliability compared to full fibre networks:

Latency: DOCSIS introduces some delay due to the way signals are encoded and decoded over the cable. This delay can add up to 3.5 milliseconds (ms) of extra latency, which might not affect general browsing but can be noticeable in online gaming or video conferencing.

Congestion: The HFC network shares bandwidth across users, and during peak times, this can lead to congestion, slowing down speeds and increasing latency.

Ageing Infrastructure: In some areas, the coaxial cables laid in the 1980s are ageing, and issues such as signal degradation or overheating amplifiers can cause outages or inconsistent performance, especially during the summer months.

Virgin’s Roll out of Full Fibre (FTTP) Broadband

Full Fibre to the Premises (FTTP), also known as Fibre to the Home (FTTH), is widely regarded as the superior technology for delivering broadband. In FTTP, fibre-optic cables run directly into homes, eliminating the need for coaxial cables. This means faster, more reliable internet with symmetrical upload and download speeds, which is ideal for today’s data-heavy applications.

Virgin Media is currently rolling out FTTP via two approaches:

1. RFoG (Radio Frequency over Glass): This system still relies on DOCSIS technology but replaces the coaxial cables outside the home with fibre. While it eliminates some issues related to older coaxial lines, it still uses DOCSIS for in-home connections, meaning the same latency and congestion issues persist.

2. XGS-PON (10 Gigabit Symmetrical Passive Optical Network): This is a true full-fibre solution, where fibre runs directly into the home, supporting symmetrical speeds of up to 10 Gbps for both downloads and uploads. Virgin’s Gig2 package, offering 2 Gbps download speeds, is exclusive to areas where XGS-PON is available.

Why Full Fibre is Better

Lower Latency: FTTP reduces latency significantly, which is crucial for gaming, live streaming, and real-time communications. Gamers on full fibre connections typically experience ping times as low as 2-5 ms, compared to 15-25 ms on DOCSIS networks.

Symmetrical Speeds: FTTP offers symmetrical upload and download speeds, which are becoming increasingly important as more people work from home, upload content, or participate in video calls.

Future Proofing: With FTTP, Virgin Media can easily upgrade to 25 Gbps or even 50 Gbps in the future, as only the equipment at either end of the fibre connection needs to be changed. DOCSIS, by contrast, would require significant infrastructure changes to achieve similar performance.

Virgin Media’s Full Fibre Transition

Virgin Media has ambitious plans to upgrade its entire network to FTTP by 2028. This will involve replacing its existing HFC network, allowing all customers to benefit from the superior speed, reliability, and low latency of fibre-to-the-home connections. By the time the transition is complete, Virgin Media’s broadband will be on par with or superior to other full-fibre networks, such as BT’s Openreach.

The cost of upgrading to full fibre is significant, but Virgin Media expects it to be more cost-effective in the long run. Currently, it costs around £100 per home to switch to FTTP, which is just £40 more than upgrading to DOCSIS 4.0, the next iteration of the DOCSIS standard. However, FTTP will eliminate the need for further investments in DOCSIS upgrades, making it a smarter long-term move.