Cisco Systems 3825 manual Loopback address on the router, 134

Appendix A Cisco 3825 Mobile Wireless Edge Router RAN-O Command Reference

xconnect

l2transport configuration (for ATM)

Connect configuration mode Global configuration

Command History	Release	Modification
	12.0(23)S	This command was introduced.
	12.0(28)S	Support was added for Multilink Frame Relay connections.
	12.3(2)T	This command was integrated into Cisco IOS Release 12.3(2)T.
	12.2(25)S	This command was integrated into Cisco IOS Release 12.2(25)S.
	12.2(27)SBC	This command was integrated into Cisco IOS Release 12.2(27)SBC.
	12.4(11)T	This command was integrated into Cisco IOS Release 12.4(11)T.
	12.4(12)MR2	This command was integrated into Cisco IOS Release 12.4(12)MR2.
Usage Guidelines	The combination of the peer-ip-addressand vcid arguments must be unique on the router. Each xconnect
	configuration must have a unique combination of peer-ip-address and vcid configuration.
Note	If the remote router is a Cisco 12000 series Internet router, the peer-ip-addressargument must specify a
	loopback address on the router.
	The same vcid value that identifies the attachment circuit must be configured using the xconnect
	command on the local and remote PE router. The vcid creates the binding between a PW and an
	attachment circuit.
	The pw-classpw-class-name value binds the xconnect configuration of an attachment circuit to a
	specific pseudowire-class. In this way, the pseudowire-class configuration serves as a template that
	contains settings used by all attachment circuits bound to it with the xconnect command.
Note	If you specify the encapsulation keywords, you must specify the pw-classkeyword.
	Keyword ignore-vpi-vci

Using the xconnect command with keyword ignore-vpi-vciprovides benefits over using the pw-pvccommand for PVC mapping.

Originally, PVC mapping was done through the pw-pvcpw-vpi/pw-vcicommand. When the MWR received the MPLS PW packet, it decoded the PW payload and looked up the PW VPI/VCI value to see if it matched any local configured PVC values. If a match was made, the PW-VPI/PW-VCI was translated to the AC-side VPI/VCI and the cell was sent to the local PVC. Without a match, the MWR dropped the received PW packet. When the MWR generated the PW packet, it used configured pw-vpi/pw-vcivalues. In this case, the PVC mapping was done completely on the MWR and was transparent to the remote end.

The scenario differs when keyword ignore-vpi-vciis configured. For N:1 with N=1 special case, when the PW packet is received from the MWR, the receiving router ignores the VPI/VCI value contained in the PW payload. It does a blind rewrite to use the AC-side VPI/VCI and sends the cell to the AC side PVC.

	Cisco 3825 Mobile Wireless Edge Router Software Configuration Guide
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