1. Implementing Quality of Service (QoS)
Classification and Marking

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Module 4
Markings
Trust Boundaries
NBAR
Class-Based Marking
Pre-Classification
QPPB
Classifying and Marking on Catalyst Switches
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3. Pre-Classification Overview
QoS for use with GRE and IPSec VPNs
An encrypted packet header cannot be read for the QoS marking
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ToS Byte Preservation
IPSec duplicates the original ToS byte into the new encrypted packet’s header
QoS mechanism sees the header and ToS byte just like normal
Since 11.3T – this even works with GRE/IPSec tunnels
ToS byte copied into GRE header, then into the IPSec header
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QoS Pre-classify
THIS IS NOT THE ToS BYTE PRESERVATION FEATURE!
This allows for QoS classification based on more than just the ToS byte
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6. QoS Pre-classify Con’t
A clone is created of all original packet headers; then the clone is used for QoS on the output interface
Cloned headers never leave the local router
GRE and IPSec are supported
Due to performance enhancements – recommended even when all you want to see is the ToS byte
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7. Configuring QoS Pre-classify
The qos pre-classify command is all that is needed
Restricted to tunnel interfaces (GRE); virtual templates (L2TP); and crypto maps (IPSec)
To verify, use show interface or show cryptomap
Also, consider verifying the QoS features you have configured
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