Users Guide

Table Of Contents
39 Per-VLAN Spanning Tree Plus (PVST+)................................................................................................... 660
Protocol Overview.........................................................................................................................................................660
Implementation Information.......................................................................................................................................... 661
Congure Per-VLAN Spanning Tree Plus.................................................................................................................... 661
Related Conguration Tasks....................................................................................................................................661
Enabling PVST+.............................................................................................................................................................. 661
Disabling PVST+.............................................................................................................................................................662
Inuencing PVST+ Root Selection...............................................................................................................................662
Modifying Global PVST+ Parameters..........................................................................................................................664
Modifying Interface PVST+ Parameters.....................................................................................................................665
Conguring an EdgePort.............................................................................................................................................. 666
PVST+ in Multi-Vendor Networks............................................................................................................................... 666
Enabling PVST+ Extend System ID............................................................................................................................. 666
PVST+ Sample Congurations..................................................................................................................................... 667
40 Quality of Service (QoS)..........................................................................................................................670
Implementation Information..........................................................................................................................................672
Port-Based QoS Congurations...................................................................................................................................672
Setting dot1p Priorities for Incoming Trac......................................................................................................... 672
Honoring dot1p Priorities on Ingress Trac..........................................................................................................673
Conguring Port-Based Rate Policing...................................................................................................................674
Conguring Port-Based Rate Shaping.................................................................................................................. 674
Policy-Based QoS Congurations................................................................................................................................675
Classify Trac.......................................................................................................................................................... 676
Create a QoS Policy.................................................................................................................................................679
Create Policy Maps.................................................................................................................................................. 681
DSCP Color Maps......................................................................................................................................................... 685
Creating a DSCP Color Map.................................................................................................................................. 685
Displaying DSCP Color Maps................................................................................................................................. 686
Displaying a DSCP Color Policy Conguration ....................................................................................................686
Enabling QoS Rate Adjustment....................................................................................................................................687
Enabling Strict-Priority Queueing................................................................................................................................ 687
Weighted Random Early Detection..............................................................................................................................688
Creating WRED Proles..........................................................................................................................................689
Applying a WRED Prole to Trac........................................................................................................................689
Displaying Default and Congured WRED Proles..............................................................................................689
Displaying WRED Drop Statistics...........................................................................................................................690
Displaying egress–queue Statistics.......................................................................................................................690
Pre-Calculating Available QoS CAM Space................................................................................................................690
Conguring Weights and ECN for WRED .................................................................................................................. 691
Global Service Pools With WRED and ECN Settings..........................................................................................692
Conguring WRED and ECN Attributes..................................................................................................................... 693
Guidelines for Conguring ECN for Classifying and Color-Marking Packets.........................................................694
Sample conguration to mark non-ecn packets as “yellow” with Multiple trac class................................. 694
Classifying Incoming Packets Using ECN and Color-Marking........................................................................... 695
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