The cost of leased lines throughout the world has been dropping rapidly and SDH-based leased line networks are growing at a record pace. Internet service providers (ISPs) worldwide anticipate huge savings both in terms of rack space and simplification in provisioning of E1 leased lines by using the channelized STM-1 optical interfaces. STM-1 offers the combined advantages of very high performance, low cost, high reliability, and immediate availability. The Cisco 10000 Edge Services Router's (ESR's) channelized STM-1 implementation supports a variety of interfaces, including DS0, DS1, E1, and DS3 connections. The four-port channelized STM-1 interface module sets a new standard for flexibility, scalability, and price/performance in the E1 aggregation market. The Cisco 10000 ESR channelized STM-1 line card provides quad OC3 interface with channelization options down to E1/DS0. The four-port STM-1 line card was developed to support high-density leased-line services for ISPs throughout the world. The Cisco 10000 ESR provides industry-leading port density as well as high processing performance using the Parallel Express Forwarding (PXF) network processor architecture for ISPs.The Cisco 10000 ESR Four-Port Channelized STM-1 Interface Module is fully hot swappable with no slot dependency. The 4-port STM-1 Interface Module is capable of supporting DS3/E1/DS1/DS0 or NxDS0 rates.