The Cisco ® I-Flex approach combines shared port adapters (SPAs) and SPA interface processors (SIPs), providing an extensible design that helps prioritize data, voice, and video services. Enterprise and service provider customers can take advantage of improved slot economics resulting from modular port adapters that are interchangeable across Cisco routing platforms. The I-Flex design maximizes connectivity options and offers superior service intelligence through programmable interface processors that deliver line-rate performance. I-Flex enhances speed-to-service revenue and provides a rich set of quality of service (QoS) features for premium service delivery while effectively reducing the overall cost of ownership. This data sheet contains the specifications for the Cisco 4-Port Serial Shared Port Adapter.

The Cisco 4-Port Serial SPA delivers flexible, high-performance WAN connectivity for enterprise and service provider networks. It provides four synchronous serial ports, each capable of speeds up to 8 Mbps.
The Cisco 4-Port Serial SPA supports a variety of interface types determined by separately purchased cable type connected to it. The supported electrical standards include EIA-232, X.21, V.35, EIA-530, EIA-530A, and EIA-449. Each port can be configured independently of the others to provide superior flexibility. Also depending on the cable type, each interface can either be configured for Date Terminal Equipment (DTE) or Data Communications Equipment (DCE).
The serial interfaces can be used to aggregate WAN connections from remote sites. The ability to support 8 Mbps per port is ideal for low- and medium-density aggregation at the head end (Figure 2.) The Cisco 4-Port Serial SPA can also be installed wherever a service provider requires an external CSU/DSU demarcation point.