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ATM Switch Router Software Configuration Guide
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Chapter16 Configuring Tag Switching and MPLS
MPLS Over Fast Ethernet Interfaces

Tag Switching Processing

To configure LER with the enhanced ATM router module acting as a tag edge proxy, perform the
following steps:
Note You must enable tag switching on the ATM interface by using the tag-switching ip command.
Note Once tag switching is enabled on an ATM interface and the interface is linked to the enhanced ATM
router module, all head-end, control, and tail-end VCs through that ATM interface terminate on the
enhanced ATM router module. All MPLS/IP packet processing is performed on the linked enhanced
ATM router module.
Note If you attempt to link an already linked ATM interface to another enhanced ATM router module
interface, an error message similar to the following results: ATM <x/x/x> is already
functioning as mpls edge for ATM <y/y/y>.
Note If you attempt to unlink an ATM interface that is not linked, an error message similar to the following
results: ATM <x/x/x> is not linked to ATM <y/y/y>.
Example
The following example shows how to link an ATM interface to an enhanced ATM router module
interface for LER MPLS functionality:
Switch# configure terminal
8540-ATM-PE1(conf)# interface atm 3/0/0
8540-ATM-PE1(conf-if)# tag-switching ip
8540-ATM-PE1(conf-if)# mpls-forwarding interface atm 10/0/1
MPLS Over Fast Ethernet Interfaces
This section describes how to configure MPLS on Fast Ethernet interfaces. By li nking a Fast Ethernet
interface to an enhanced ATM router module interface, tag or MPLS switching can be enabled on Fast
Ethernet interfaces and Fast Ethernet interfaces can be part of a VPN. The e nhanced ATM router module
(ARM) serves as the MPLS processor on behalf of the Fast Ethernet card. The Fast Ethernet interface
Command Purpose
Step1 Switch(config)# interface atm card/subcard/port
Switch(config-if)#
Selects the interface to be configured.
Step2 Switch(config-if)# tag switching ip Enables mpls on the ATM interface
Step3 Switch(config-if)# mpls-forwarding interface
atm card/subcard/port
Links the specified ATM interface to the
enhanced ATM router module interface, which
acts as an MPLS edge proxy.