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Appendix B. Example Bandwidth Reservation Scenarios

B.1. Scenario 1: No Bandwidth Reservation​

Consider the case where a network administrator elects to:

  • have Diff-Serv resources entirely provisioned off-line (e.g., via Command Line Interface, via SNMP, via COPS,...)

  • have Shortest Path Routing used for all the Diff-Serv traffic.

This is the closest model to provisioned Diff-Serv over non-MPLS IP. In that case, E-LSPs and/or L-LSPs would be established without signaled bandwidth.

B.2. Scenario 2: Bandwidth Reservation for per-PSC Admission Control​

Consider the case where a network administrator elects to:

  • have Diff-Serv resources entirely provisioned off-line (e.g., via Command Line Interface, via SNMP, via COPS,...)

  • use L-LSPs

  • have Constraint Based Routing performed separately for each PSC, where one of the constraints is availability of bandwidth from the bandwidth allocated to the relevant PSC.

In that case, L-LSPs would be established with signaled bandwidth. The bandwidth signaled at L-LSP establishment would be used by LSRs to perform admission control at every hop to ensure that the constraint on availability of bandwidth for the relevant PSC is met.

B.3. Scenario 3: Bandwidth Reservation for per-PSC Admission Control and per-PSC Resource Adjustment​

Consider the case where a network administrator elects to:

  • use L-LSPs

  • have Constraint Based Routing performed separately for each PSC, where one of the constraints is availability of bandwidth from the bandwidth allocated to the relevant PSC.

  • have Diff-Serv resources dynamically adjusted

In that case, L-LSPs would be established with signaled bandwidth. The bandwidth signaled at L-LSP establishment would be used by LSRs to attempt to adjust the resources allocated to the relevant PSC (e.g., scheduling weight) and then perform admission control to ensure that the constraint on availability of bandwidth for the relevant PSC is met after the adjustment.