23-2
Cisco 7600 Series Router Cisco IOS Software Configuration Guide, Release 12.2SX
OL-4266-08
Chapter 23 Configuring UDE and UDLR
Understanding UDE and UDLR
Unidirectional links are advantageous because when you transmit mostly unacknowledged
unidirectional high-volume traffic (for example, a video broadcast stream) over a high-capacity
full-duplex bidirectional link, you use both the link from the source to the receiver and the equally
high-capacity reverse-direction link, called the “back channel,” that carries the few acknowledgements
from the receiver back to the source.
UDE and UDLR support use of a high-capacity unidirectional link for the high-volume traffic without
consuming a similar high-capacity link for the back channel. UDE provides a high-capacity
unidirectional link. UDLR provides the back channel through a tunnel that is configured over a
regular-capacity link, and also provides bidirectional link emulation by transparently making the back
channel appear to be on the same interface as the high-capacity unidirectional link.
Supported Hardware
On Cisco 7600 series routers, UDE and UDLR are supported on the interfaces of these switching
modules:
•
WS-X6704-10GE 4-port 10-Gigabit Ethernet
•
WS-X6816-GBIC 16-port Gigabit Ethernet
•
WS-X6516A-GBIC 16-port Gigabit Ethernet
•
WS-X6516-GBIC 16-port Gigabit Ethernet
Understanding UDE
These sections describe UDE:
•
UDE Overview, page 23-2
•
Understanding Hardware-Based UDE, page 23-2
•
Understanding Software-Based UDE, page 23-3
UDE Overview
On Cisco 7600 series routers, you can implement UDE with hardware or in software. Hardware-based
UDE and software-based UDE both use only one strand of fiber instead of the two strands of fiber
required by bidirectional traffic.
The unidirectional transceiver determines whether hardware-based UDE is receive-only or
transmit-only. You can configure software-based UDE as either transmit-only or receive-only.
You do not need to configure software-based UDE on ports where you implement hardware-based UDE.
Note
Refer to the
“Supported Hardware” section on page 23-2
for a list of the module with interfaces that
support hardware-based UDE and software-based UDE.
Understanding Hardware-Based UDE
You can create a unidirectional link by using a unidirectional transceiver. Unidirectional transceivers are
less expensive than bidirectional transceivers. Release 12.2(18)SXE and later releases support these
unidirectional transceivers: