Dynamic LSP Routing and CSPF
If an LSP contains no LSP paths (also called MPLS TE tunnel paths ), it is routed dynamically using CSPF. The weights used for the CSPF calculation are the TE metrics per interface. If the TE metric is not configured for an interface, the IGP metric is used.
If there are equal-cost routes, the following selection criteria apply in this order:
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Bandwidth available—The route with the greatest reservable bandwidth is chosen.
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Hop count—The route with the fewest hops is chosen.
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Random—If neither of the above criteria can be used, the route is randomly chosen.
CSPF properties are set in the LSP Properties dialog box and are viewable from the LSPs table.
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Setup Bandwidth—The amount of traffic the source node requests for this LSP in Mbps. The requested bandwidth is available from the reservable bandwidth of each interface in the path.
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Autobandwidth—Dynamically update the Setup BW Sim value when using the Autobandwidth Convergence mode.
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Setup Priority—A priority for allocating reservable bandwidth. This is the order in which the LSPs are signaled. The lower the number, the higher the priority.
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Hold Priority—Priority that can preempt LSPs that are on the shortest path. This is typically set for a particular service or traffic type. The lower the number, the higher the priority.
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Hop Limit—The maximum number of hops permitted in the LSP route. If no path is available with this number of hops or fewer, the LSP is not routed.
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TE Metric Disabled—If checked, the LSP is routed using IGP metrics. If unchecked (default), the LSP is routed using TE metrics.
Interface MPLS Properties
Related MPLS properties are set in the MPLS tab of the interface or circuit Properties dialog box, and are viewable in the Interfaces table.
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TE Metric—Determines which path an LSP takes.
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TE Metric Sim—Derived column that shows the effective TE metric. If the TE Metric is empty, this is set to the IGP metric.
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TE Enabled—Identifies whether an LSP can be routed over the interface. If checked, the value is set to T (True), and TE metrics are used in routing the LSP provided the LSP’s TE Metric Disabled is unchecked (False).
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Resv BW—Shows the amount of bandwidth that can be reserved by LSPs routed over the interface.
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Resv BW Percent—Shows the percentage of bandwidth that can be reserved by LSPs routed over the interface.
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Resv BW Sim—Derived column.
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If a Resv BW value is entered, this is copied to the Resv BW Sim column.
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If Resv BW and Resv BW Percent are “na,” the Resv BW Sim is copied from the Capacity Sim column.
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If Resv BW is “na,” but Resv BW Percent has a value, the Resv BW Sim value is derived by this formula:
Capacity Sim * (Resv BW Percent / 100)
If needed, you can change this behavior so that reserved bandwidth constraints are not used during simulations, which could be useful for planning purposes. For information, see Ignoring Reservable Bandwidths for Capacity Planning.
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Affinities—Lists which affinities are set. For more information, see Affinities.
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Loadshare—Value for redistributing either traffic across LSPs based on the ratio of this value with other LSPs that are parallel (have the same source and destination).
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FRR Enabled—Designated interface to be avoided by the FRR LSP. Only interfaces with this property set are used by the FRR LSPs initializer when creating FRR LSPs. This property does not affect FRR LSPs that are manually created. For more information, see Fast Reroute Simulations.
To determine how much of the interface traffic is contained in LSPs, show these columns in the Interfaces table. The total of the two equals Traff Sim.
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Traff Sim LSP—The total amount of LSP traffic on the interface.
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Traff Sim Non LSP—The total amount of non-LSP traffic on the interface.
To determine which interfaces carry LSP traffic, sort the columns. To determine the demands associated with one or more selected interfaces based on whether or not they have LSP traffic, right-click one and choose Filter to Demands Through Interfaces. Then choose either In LSP or Not in LSP
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Viewing LSP Reservations
To view the LSP reservations on the interfaces, choose LSP Reservations from the Network Plot View in the Visualization toolbar (LSP Reservations View). The width of the circuit displayed in the network plot is set according to the Resv BW Sim column in the Interfaces table. The utilization colors are based on the LSP Util column in the Interfaces table. The LSP Util is the sum of all setup bandwidths for all LSPs through the interface, as a percentage of the Resv BW Sim.
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LSP Setup BW Initializer
The LSP Setup BW Initializer calculates the setup bandwidth for existing RSVP-TE LSPs. The setup bandwidth is set to the maximum amount of demand traffic passing through the LSP for the traffic levels selected.
If using only one traffic level, the best practice is to use the Autobandwidth Convergence mode. For information, see Advanced RSVP-TE LSP Simulations.
Procedure
Step 1 |
Choose one ore more LSPs from the LSPs table. |
Step 2 |
Choose Initializers > LSP Setup BW, or right-click one of the selected LSPs and choose LSP Setup BW Initializer. |
Step 3 |
Choose which traffic levels to use for demand traffic. |
Step 4 |
Choose whether to set the load share values to be equal to the setup bandwidth. |
Step 5 |
Click OK. |