Single-Chip Control/Data-Plane Processor (News - Alert) (SCDP) technology is being deployed today, mainly in low-end applications. As semiconductor processes improve, it will inevitably move into higher-speed designs.

Industry analyst Linley Gwennap has recently published a study which examines this trend towards combining control-plane and data-plane processing on a single chip.

Linley focuses on two areas of deployment, excerpts follow:

Consumer and SOHO

At the low end of the networking market, such as equipment for consumer or SOHO (small office/home office) use, data throughput is typically less than 10Mbps. At these rates, both the control plane and data plane can be handled in software on a CPU running at less than 400MHz.

This type of low-cost CPU can be licensed from several sources and integrated into a system-on-a-chip (SoC) device to form the core of a low- cost router or broadband gateway. We do not consider these devices to be SCDP because they do not integrate any data-plane functions, other than perhaps an encryption offload engine.

Throughput requirements are increasing, however, due to the deployment of next- generation broadband technologies such as VDSL, PON, and DOCSIS 3 (cable modem). These technologies can supply from 30Mbps to 100Mbps or more into a home or small office. In addition, 802.11n provides wireless transmission rates of 100Mbps or more. At these data rates, a single CPU engine cannot perform both the control and data planes.

Small/Medium Businesses

Historically, SMB has used a hodge-podge of network connections, including T1/E1, fractional T3/E3, HDLC, and SHDSL. Many of these connections use the ATM protocol and thus require greater levels of processing to convert them to the TCP/IP protocol used for the internal Ethernet network.

SMB equipment typically uses products such as Freescale’s (News - Alert) PowerQuicc, which combines a Power CPU with a programmable data-plane engine. This engine handles the data plane, including protocol conversion, while the CPU handles the control plane and application-layer processing.

With these legacy connections falling behind in bandwidth, many small businesses are switching to next-generation broadband links, while medium-size businesses are plug- ging into carrier Ethernet service at 100Mbps or even 1Gbps. Although these new ser- vices use TCP/IP, eliminating the protocol conversion, their data rates are much greater than in the past. As a result, many SMB products continue to use an SCDP design.