Uncompressed Single-Link DVI Bandwidth Over Ethernet

Streaming uncompressed single-link DVI video over an IP network requires a transmission capacity of approximately 4 Gbps to accommodate the highest standard display modes. Because standard single-link DVI supports a maximum pixel clock rate of 165 MHz at 24 bits per pixel, raw video transmission generates up to 3.96 Gbps of uncompressed video payload. Once Ethernet, IP, and transport protocol overheads are factored in, standard 1 Gigabit Ethernet (1GbE) and multi-gigabit connections fall short, making 10 Gigabit Ethernet (10GbE) the minimum network infrastructure required for reliable, uncompressed transmission.

Single-link Digital Visual Interface (DVI) relies on Transition-Minimized Differential Signaling (TMDS) to transmit digital video data across three physical data channels (red, green, and blue).

The maximum pixel clock frequency defined by the DVI 1.0 specification for single-link operation is 165 MHz. Each pixel consists of 24 bits of color data (8 bits per channel in RGB color space). The raw throughput required for the active video and blanking intervals is calculated as follows:

  • Pixel Clock: 165,000,000 pixels per second
  • Color Depth: 24 bits per pixel (bpp)
  • Raw Video Bitrate: 165,000,000 × 24 = 3,960,000,000 bits per second (3.96 Gbps)

For standard resolutions operating within this specification:

  • 1080p (1920×1080 at 60 Hz): With standard blanking, the pixel clock is roughly 148.5 MHz, resulting in an uncompressed stream of approximately 3.56 Gbps.
  • WUXGA (1920×1200 at 60 Hz): With reduced blanking, the pixel clock operates at roughly 154 MHz, generating roughly 3.70 Gbps. Standard blanking pushes the rate to the maximum 165 MHz clock (3.96 Gbps).

Network Overhead and Encapsulation

Transporting video frames over an Ethernet network involves packetizing the raw pixel data into transport protocols, typically Real-time Transport Protocol (RTP) over User Datagram Protocol (UDP) and Internet Protocol (IP).

Encapsulation adds headers at each layer:

  • Ethernet Header and Inter-Packet Gap: Preamble, MAC addressing, and frame check sequences.
  • IP/UDP/RTP Headers: Addressing, packet sequencing, and timestamping data.

Network framing and packetization add between 1% and 3% overhead to the raw stream, depending on the Maximum Transmission Unit (MTU) size. Utilizing standard 1500-byte MTUs produces higher overhead, whereas configuring jumbo frames (e.g., 9000 bytes) reduces CPU load and header overhead. Accounting for this network encapsulation, the total continuous bandwidth required to transport a maximum single-link DVI stream ranges between 4.0 Gbps and 4.1 Gbps.

Ethernet Infrastructure Requirements

Network standards dictate the practical hardware necessary to support this stream:

  • 1 GbE (Gigabit Ethernet): Inadequate. With a maximum practical throughput of ~940 Mbps, 1GbE can only carry compressed video (such as H.264, HEVC, or JPEG-XS).
  • 2.5 GbE and 5 GbE (NBASE-T): Inadequate for full-bandwidth, single-link DVI. While 5GbE provides enough theoretical bandwidth for 3.96 Gbps, it leaves negligible headroom for network fluctuations, burstiness, or packet jitter, risking packet loss and frame drops.
  • 10 GbE (10 Gigabit Ethernet): The necessary standard. Providing 10 Gbps of full-duplex capacity via copper (10GBASE-T) or fiber (SFP+), 10GbE easily handles the ~4.1 Gbps uncompressed stream alongside network management traffic, control signals, and multi-channel uncompressed audio with ample headroom.