Data Sheet
Cisco 12000 Series
Two-Port Channelized OC-3c/STM-1c (DS1/E1) Line Card
The Cisco 12000 Series Two-Port Channelized OC-3c/STM-1c (DS1/E1) Line Card provides Cisco 12000 Series Internet Routers support for DS-1/E-1 aggregation. Designed for telcos and Internet service providers (ISPs), this card supports two OC-3c/STM-1c ports, each of which can be configured with multiple channels of (n)xDS-1, DS-1, fractional DS-1, or DS-0 in a Synchronous Optical Network (SONET) environment or (n)xE-1, E-1, fractional E-1, or 64 kbps in a Synchronous Digital Hierarchy (SDH) environment. Cisco 12000 Series channelized line cards integrate the channel service unit/data service unit (CSU/DSU) function on a per-port basis. In conjunction with other Cisco 12000 Series line cards, a single router in the carrier point of presence (POP) can scale fractional DS-1 to OC-192c in a SONET environment and from fractional E-1 to STM-64c (VC-4-64c) in an SDH environment.
Figure 1
Cisco 12000 Series Two-Port Channelized OC-3c/STM-1c (DS1/E1) Line Card

Product Description
The Cisco 12000 Series Two-Port Channelized OC-3c/STM-1c (DS1/E1) Line Card (2-Port CHOC-3) provides advanced DS-1/E-1 aggregation, with two optical connections (Figure 1). Each interface, when configured in SDH framing mode, is capable of supporting channelization into 63 independent E-1 (VC-12 mapping) channels in an SDH configuration. When configured for SONET framing mode, each interface is capable of supporting channelization into 84 independent DS-1 (VT1.5 mapping or CT-3 mapping into STS-1) channels in a SONET configuration. Fractional E-1 and individual 64 kbps channels can also be configured, up to the limit of 105 channel-group definitions per STM-1 (35 per TUG-3). Fractional T-1 and individual DS-0 channels can also be configured, up to the limit of 35 channel-group definitions per STS-1 (210 per line card). Each Cisco 2-Port CHOC-3 Line Card supports up to 126 E-1 connections in an SDH configuration and 168 DS-1 connections in a SONET configuration, or any combination of
DS-0/64 kbps, fractional T-1/E-1, and
T-1/E-1 interface definitions up to 210 channel groups per line card.
The Cisco 2-Port CHOC-3 Line Card supports full class of service (CoS) on each and every interface, including Multilink Point-to-Point Protocol (MLPPP) bundles. Eight CoS queues, along with weighted random early detection (WRED) and modified deficit round robin (MDRR), provide the same CoS for individual serial interfaces as all other Cisco 12000 Series line cards, up to and including the Cisco One-Port OC-192c/STM-64c Packet Over SONET (POS) Line Card. This provides the infrastructure required to enable service providers to provision CoS throughout their entire network, rather than sacrificing this essential capability at the very point (relatively smaller links) where it is needed the most.
The Cisco 2-Port CHOC-3 Line Card can be used in any Cisco 12000 Series Internet Router. All Cisco 12000 Series line cards support "hitless" online insertion and removal (OIR).
The Cisco 2-Port CHOC-3 Line Card supports the full richness of the Cisco IOS® Software service provider feature set. This enables service providers to deploy a wide range of services across their entire network, whether DS-1/E-1 or OC-192c/STM-64c; no compromise or tradeoff is required for lower-speed links.
Applications
SDH Aggregation
SDH as a transport technology is an established technology in E-1 carrier regions. Most operators, incumbents and new ones, have significant investment in large SDH networks deployed mainly in metro and regional access networks, typically to support voice traffic. The reasons for using SDH for access are:
- The need to support voice and data services over the same transport aggregate
- SDH is a known technology having good performance, error monitoring, and resilience
- SDH supports centralized service provisioning at various bandwidths, from E-1 to E-3/DS-3, full STM-1c, and beyond
- SDH provides better utilization of existing transmission infrastructure
Service providers can exploit deployed SDH to provision both voice and data circuits all the way to a customer's premises. The Cisco 2-Port CHOC-3 Line Card takes advantage of existing infrastructure, significantly lowering provisioning costs in terms of transmission and routing equipment.
Traditionally, data leased-line aggregation has been deployed using Frame Relay and Asynchronous Transfer Mode (ATM) networks deployed over SDH networks. In cases where leased lines were provided by a global or continental service provider, the E-1 or fractional E-1 leased lines were transported over the transmission provider SDH network and handed over using E-1 connectivity to the service provider POP (Figure 2).
Figure 2
STM-1c to Channelized E-1 Aggregation

As businesses require greater bandwidth connectivity to support increased IP traffic loads, E-1 and greater bandwidth are becoming increasingly common for access connections. The growth in the number of provisioned E-1 service connections is driving the need for more E-1 port capacity on service provider aggregation routers, requiring more routers, space, and power in their POPs. The Cisco 2-Port CHOC-3 Line Card allows service providers to connect multiple E-1 leased-line customers into one Cisco 12000 Series Internet Router line card slot, greatly reducing the amount of aggregation equipment and interconnectivity needed between edge and backbone routers, as well as enabling support of single router (edge and backbone) POP architectures (Figure 2).
By supporting both PPP and Frame Relay, the line card allows easy transition of connectivity from Frame Relay networks to direct IP leased-line grooming over SDH networks, thus allowing a simple transition to high-bandwidth, full-feature aggregation solutions on Cisco 12000 Series Internet Routers.
Key Features and Benefits
Designed for concentrating IP access over telco time-division multiplexing (TDM) networks, the Cisco 2-Port CHOC-3 Line Card:
- Concentrates up to 168 DS-1s in one line card. This increases density per rack and overall router capacity, enabling service providers to scale networks cost-effectively.
- Supports any combination of DS-0/64 kbps, fractional T-1/E-1, and T-1/E-1 interface definitions up to 210 channel groups per line card. Service providers can accommodate customers using telco TDM networks for access with a wide range of bandwidth requirements, from DS-0 to multiple T-1s and E-1s.
- Provides guaranteed priority packet delivery for both IP and Multiprotocol Label Switching (MPLS) traffic. This includes MDRR queuing algorithm, which provides low-latency queuing for high-priority applications such as voice over IP, and unique priority-based WRED, which provides congestion control. Packet sequence integrity is not compromised under any condition.
- Supports service-transparent online insertion and removal, allowing line cards to be removed without impacting traffic.
Cisco continues to build on its technical leadership in high-end Internet routing with the introduction of the Cisco 12000 Series Two-Port Channelized OC-3c/STM-1c (DS1/E1) Line Card. The Cisco 12000 Series is the premier Internet routing platform for building the highest capacity and highest value IP networks. When coupled with the Cisco 2-Port CHOC-3 Line Card, it provides high density T-1 and E-1 aggregation enabling service providers to build powerful, cost-efficient networks to serve large numbers of customers using telco infrastructure for IP access.
Table 1 Product Specifications
Table 2 Supported SONET/SDH Alarm and Signal Events
Ordering Information
Description | Part Number |
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Cisco 12000 Series Two-Port Channelized OC-3c/STM-1c (DS1/E1) Line Cardincludes 128 MB default route memory with ECC |
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Service and Support
Cisco offers a wide range of service support offerings for its service provider customers. Cisco has earned the highest customer satisfaction ratings in the industry by providing the world-class service and support necessary to deploy, operate, and optimize service provider networks. Whether the goal is speed to market, maximizing network availability, or enhancing customer satisfaction and retention, Cisco is committed to the success of its service provider customers.
For More Information
For more information on Cisco service and support programs and benefits, go to http://www.cisco.com/public/Support_root.shtml.
For more information about the Cisco 12000 Series and the Cisco family of next-generation Internet routers, visit http://www.cisco.com, or call Cisco.