Chapter 23
Configuring UDE and UDLR
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Understanding Software-Based UDE
You can create a unidirectional link by configuring ports equipped with bidirectional transceivers to
unidirectionally transmit or receive traffic. You can use software-based UDE when there is no
appropriate unidirectional transceiver available. For example, with no support for any transmit-only
transceivers, you must configure transmit-only links with software-based UDE.
Understanding UDLR
UDLR provides a unidirectional tunnel as the back channel of a unidirectional high-capacity link, and
transparently emulates a single bidirectional link for unicast and multicast traffic.
UDLR intercepts packets that need to be sent on receive-only interfaces and sends them on UDLR
back-channel tunnels. When routers receive these packets over UDLR back-channel tunnels, UDLR
makes the packets appear as if received on send-only interfaces.
UDLR back-channel tunnels support these IPv4 features:
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UDLR back-channel tunnels do not support IPv6 or MPLS.
Note
Configuring UDE and UDLR
These sections describe how to configure UDE and UDLR:
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This caveat is open in releases that support UDLR: Neighboring ISIS routers are not seen through a
Note
UDLR topology. (CSCee56596)
Configuring UDE
These sections describe how to configure UDE:
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OL-4266-08
Receive-only WDM GBIC (WDM-GBIC-REC=)
Receive-only XENPAK (WDM-XENPAK-REC=)
Address Resolution Protocol (ARP)
Next Hop Resolution Protocol (NHRP)
Emulation of a bidirectional link for all IPv4 traffic (as opposed to only broadcast and multicast
control traffic)
IPv4 GRE multipoint at a receive-only tunnels
Configuring UDE, page 23-3
Configuring UDLR, page 23-6
UDE Configuration Guidelines, page 23-4
Configuring Hardware-Based UDE, page 23-4
Configuring Software-Based UDE, page 23-5
Cisco 7600 Series Router Cisco IOS Software Configuration Guide, Release 12.2SX
Configuring UDE and UDLR
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