Chapter 7 Configuring the Switch Ports
Configuring the LRE Ports
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Catalyst 2900 Series XL and Catalyst 3500 Series XL Software Configuration Guide
78-6511-05
Configuring the LRE Ports
The Catalyst 2900 LRE XL switches use Long-Reach Ethernet (LRE) technology
to transfer data and voice traffic over existing standard telephone lines.
Connecting a switch LRE switch port to a remote Ethernet device requires two
types of connections:
• LRE link—This is the connection between the switch LRE port and the
WALL port on the Cisco 575 LRE customer premises equipment (CPE). This
connection can be through a standard telephone line (categorized and
noncategorized unshielded twisted-pair cable) and can extend to distances of
up to 4921 ft (1500 m).
• Ethernet link—This is the connection between the 10/100 Ethernet port on
the CPE and an Ethernet device, such as a PC. This connection is through
standard Category 5 cabling and can extend to distances of up to 328 ft
(100 m).
The actual link rate between an LRE port and a remote Ethernet device, in either
direction, depends on the active profile for the LRE port and the Ethernet link
speed. For example, if a PC Ethernet port is configured to 100 Mbps and the LRE
port is configured with an upstream link rate of 5.69 Mbps, the actual upload rate
provided to the PC user is 5.69 Mbps, not 100 Mbps. Conversely, if the PC
Ethernet port is configured to 10 Mbps and the LRE port is configured with an
upstream link rate of 17.06 Mbps, the actual upload rate provided to the PC user
is 17.06 Mbps.
LRE Links and LRE Profiles
The LRE link settings on the LRE ports define the connection between the switch
LRE port and the WALL port on the Cisco 575 LRE CPE. The LRE link provides
symmetric and asymmetric bandwidth for voice and data traffic. Symmetrical
transmission is when the downstream and upstream bandwidth are the same.
Asymmetrical transmission is when the downstream and the upstream bandwidth
differ. Downstream transmission refers to the data traveling from the LRE port to
the CPE. Upstream transmission refers to the data traveling from the CPE to the
LRE port.
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