ATM LSR
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ATM LSR
Reference: A white paper from Juniper NetworksAppendix I: Cell-switched MPLS Operational Model
in“Migration Strategies for IP Service Growth: Cell-
switched MPLS or IP-routed MPLS” by Chuck Semeria
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ATM LSR
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ATM LSR
Unique features of ATM LSRs: • Must exchange control-plane IP packets over an
ATM-control VC. SAR is required• Use of VCI or VPI/VCI fields to carry label• Pushing or popping labels within an ATM LSR
domain is not supported• New mechanisms for detecting and preventing
loops
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ATM LSRShips-in-the-Night
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ATM LSRShips-in-the-Night
• Issues: – Label space partitioning– Resource partitioning– CoS and QoS support
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ATM LSR
Using both VPI and VCI fields for direct connection:
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ATM LSR
Using VCI Field for Indirect Connection:
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ATM LSR
Frame based MPLS encapsulation:
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ATM LSR
Cell based MPLS encapsulation:
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ATM LSR
Label Merging at frame based LSR
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ATM LSR
VC Merge at ATM LSR:
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ATM LSR
Advantages of ATM MPLS over IP over ATM: • Single control plane• Removing the need for N^2 full meshed
connectivity among edge routers• Simplify the QoS management: now CoS to LSP
mapping is possible• Native ATM can be supported
Problems: • Cell tax• SAR bottleneck