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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
forwards all MPLS packets it receives to the enhanced ATM router module. It also forwards all IP
packets to the enhanced ATM router module if a VRF is configured on the Fast Ethernet or if the
outgoing interface is MPLS-enabled. The enhanced ATM router module processes the packets a nd
forwards them to the appropriate outgoing port.
Note IPX routing and MPLS processing are incompatible. You must remove all IPX routing configuration
from the Fast Ethernet interface with which you wish to link, and from all Fast Ethernet interfaces on
the interface module controlled by the same Ethernet proce ssor interface, before configuring MPLS.
Each Ethernet processor interface controls four Fast Ethernet interfaces on the interface module. On a
16-port Fast Ethernet interface module, ports 0 through 3 are controlled by one Ethernet processor
interface, ports 4 through 7 by another, and so forth. For example, if you want to configure an MPLS
control link on Fast Ethernet interface 3/0/1, you must remove all IPX configuration from interfaces
3/0/0, 3/0/1, 3/0/2, and 3/0/3.
Configuring MPLS on Fast Ethernet Interfaces
To configure a MPLS for a Fast Ethernet interface, perform the following steps:
Example
The following example shows how to configure a Fast Ethernet interface and link it to the enhanced ATM
router module for processing:
Switch# configure terminal
Switch(conf)# interface fastethernet 3/0/0
Switch(conf-if)# tag-switching ip
Switch(conf-if)# ip address 12.0.0.2 255.0.0.0
Switch(conf-if)# mpls-forwarding interface ATM2/0/0
Switch(conf-if)# end
Switch#
MPLS configuration on a Fast Ethernet interface has the following software restrictions:
•Subinterfaces on a Fast Ethernet interface cannot be linked to e nhanced ATM router module
interfaces.
•VPN can be configured on the Fast Ethernet interface using the ip vrf forwarding vrf-name
command and linking it to an ARM interface using the mpls-forwarding interface command.
•The enhanced ATM router module provides efficient MPLS processing for four Fast Ethernet
interfaces.
•Pings may fail between an all MPLS configuration of Fast Ethernet interfaces, which are not
associated with an active Enhanced ATM router module even though TDP or LDP might comes up
and stays up. When the TDP comes up it causes the MPLS tags to be distributed which causes ping
packets to reach the Fast Ethernet interfaces as tagged packets but are then dropped.
Command Purpose
Step1 Switch(config)# interface fastethernet
card/subcard/port
Switch(config-if)#
Selects the Fast Ethernet interface to be
configured.
Step2 Switch(config-if)# mpls-forwarding interface
atm card/subcard/port
Links a Fast Ethernet interface to an enhanced
ATM router module interface, which performs
VPN processing for a Fast Ethernet interface