Configure MPLS over ATM pointtopoint subinterfaces on the routers
When an underlying ATM infrastructure that does not support cell-mode MPLS is used, MPLS can still be used across point-to-point permanent virtual circuits (PVCs). The MPLS configuration is equal to that on any other Layer 2 media.
This activity could be the first phase of an ATM network migration.
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• Routers view the ATM PVC as a frame-mode MPLS interface.
• TDP or LDP is run between the adjacent routers.
• Many LSPs can be established over one ATM PVC.
• The ATM network is not aware of MPLS between the routers.
If frame-mode MPLS on an ATM interface is enabled, TDP or LDP neighbor relationships are established between the two PVC endpoint routers and not with the attached ATM switch.
Labeling of packets happens at the process level (in software), while segmentation and reassembly happen on the interface (in hardware), regardless of the type of packet.
Switching is performed based on the virtual path identifier/virtual channel identifier (VPI/VCI) value in the ATM header that is used for this particular PVC, and is not related to Layer 3 IP information.
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Create a point-to-point ATM subinterface.
Configure ATM PVC on the subinterface.
Start label switching and LDP or TDP on the interface.
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Configuring frame-mode MPLS on an ATM interface involves using the same interface command (mpls ip). Because this implementation is frame-mode MPLS (versus cell-mode) over ATM, the interface is defined as a point-to-point subinterface.
The ATM parameters are not related to MPLS, because the labeled traffic is using a standard ATM Forum point-to-point PVC.
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The PDF files and any printed representation for this material are the property of Cisco Systems, Inc., for the sole use by Cisco employees for personal study. The files or printed representations may not be used in commercial training, and may not be distributed for purposes other than individual self-study.
Create a point-to-point or multipoint Frame Relay subinterface. Configure Frame Relay DLCI on the subinterface. Start label switching and LDP or TDP on the interface.
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Enabling MPLS on a Frame Relay PVC, also called a data-link connection identifier (DLCI), is no different from doing so on any other point-to-point media.
Routers insert a label between the frame and the IP header. The TDP or LDP session is established between the two IP endpoints connected through a Frame Relay network.
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The PDF files and any printed representation for this material are the property of Cisco Systems, Inc., for the sole use by Cisco employees for personal study. The files or printed representations may not be used in commercial training, and may not be distributed for purposes other than individual self-study.
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