Product Overview; Long-Reach Ethernet Technology - Cisco Catalyst 2950 Datasheet

Product Overview

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The Cisco Catalyst 2950 LRE switches are fixed-configuration, stackable models that provide wire-speed LRE and
Gigabit Ethernet connectivity for small and midsized networks. The Catalyst 2950 Series is an affordable product line
that brings intelligent services, such as enhanced security, high availability and advanced quality of service (QoS), to
the network edge—while maintaining the simplicity of traditional LAN switching. When a Catalyst 2950 LRE switch
is combined with a Catalyst 3550 Series switch, the solution can enable IP routing from the edge to the core of the
network. Embedded in Catalyst 2950 Series switches is the Cisco Cluster Management Suite (CMS) Software, which
allows users to simultaneously configure and troubleshoot multiple Catalyst desktop switches using a standard Web
browser. In addition to CMS, Cisco Catalyst 2950 LRE switches provide extensive management tools using Simple
Network Management Protocol (SNMP) network management platforms such as CiscoWorks for Switched
Internetworks.
The Cisco 2950 LRE solution includes the Cisco Catalyst
Premise Equipment (CPE) devices, and the Cisco LRE POTS Splitter. Each LRE link is terminated with either the Cisco
575 or 585 LRE CPEs, and a POTS splitter is required when POTS traffic coexists with the LRE link over the same
line.
The Cisco Catalyst 2950 LRE switches consist of the following devices—which are based upon the Enhanced Image
(EI) Software for the Catalyst 2950 Series.
• Catalyst 2950ST-24-LRE— 24 LRE ports + 2 10/100/1000BASE-T ports + 2 Small Form-Factor Pluggable (SFP)
ports (two of the four uplinks active at one time)
• Catalyst 2950ST-8-LRE— 8 LRE ports + 2 10/100/1000BASE-T ports + 2 SFP ports (two of the four uplinks active
at one time)
The two built-in Gigabit Ethernet SFP ports support 1000BASE-SX and 1000BASE-LX modules. The dual SFP-based
and copper Gigabit Ethernet implementation provides customers with tremendous deployment flexibility—allowing
customers increased availability with the redundant uplinks. High levels of stack resiliency can also be implemented
by deploying dual redundant Gigabit Ethernet uplinks and UplinkFast technologies for high-speed uplink and stack
interconnection failover, and Per VLAN Spanning Tree Plus (PVST+) for uplink load balancing.

Long-Reach Ethernet Technology

The LRE technology employs Quadrature Amplitude Modulation (QAM). QAM modulation uses both signal
amplitude and phase to define each symbol. LRE uses the most sophisticated QAM technology with various
QAM modulations (QAM-256, QAM-128, QAM-64, QAM-32, QAM-16, QAM-8, and QAM-4). The system
administrator may choose profiles that use different modulations and frequency plans according to the line
specification and rate definition. LRE is designed to support multiQAM in order to achieve performance as close
to the physical limit as possible, while maintaining low cost and low power.
Cisco LRE facilitates the transport of symmetrical, bi-directional data over unshielded, copper twisted-pair telephone
wires originally intended for the frequency band between 300 Hz and 3.4 KHz. The system employs Frequency
Division Duplexing (FDD) to separate the downstream channel, the upstream channel, and POTS, ISDN, or PBX
signaling services in the frequency domain. This enables service providers to overlay LRE on existing POTS, ISDN,
or analog PBX signaling services without disruption. Both LRE and POTS/ISDN/analog PBX services may be
transmitted over the same line without interfering with each other.
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2950 LRE switches, the Cisco 575 and 585 LRE Customer
Cisco Systems, Inc.
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