Modular QoS Configuration Guide for Cisco 8000 Series Routers, Cisco IOS XR Release

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Modular QoS Configuration Guide for Cisco 8000 Series Routers, Cisco IOS XR Release

Information flow

Updated: June 9, 2026

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Introduces the QoS information flow across network scenarios, showing how classification, marking, queuing, policing, shaping, and forwarding behavior interact across QoS-enabled traffic paths.

This content explains how QoS can be deployed in various network scenarios. It focuses on how classification and queuing decisions are influenced by traffic type and tunneling methods. The content also describes configurations that extend QoS capabilities beyond standard interfaces, such as Border Gateway Protocol (BGP) policy propagation, pseudowire headends and Bridged Virtual Interface (BVI) two-pass QoS.

Table 1. Information flow
Deployment scenario	What it covers	What it helps you achieve
QoS support for VPWS traffic	Describes how QoS classification and remarking are applied to Virtual Private Wire Service (VPWS) traffic on Layer 2 attachment circuits. Explains ingress classification based on IEEE 802.1p Priority Code Point (PCP) and Drop Eligible Indicator (DEI) fields in the VLAN header, and the use of QoS policies on VPWS traffic flows.	Enables consistent and differentiated service treatment for point-to-point Layer 2 services. Ensures predictable QoS behavior for VPWS traffic by preserving and acting on Layer 2 priority information at ingress.
QoS Policy Propagation via BGP	Describes how QoS classification and marking can be derived from BGP route attributes instead of ACLs. Explains the process of mapping prefixes to QoS groups and applying policies through routing table integration.	Enables scalable, destination-based QoS classification and consistent marking across networks where BGP is the control plane. Reduces manual ACL management and improves classification accuracy.
QoS on Pseudowire Headend	Explains how QoS policies apply to traffic bridging between Layer 2 and Layer 3 domains through BVIs. Covers marking, policing, and shaping behavior for bridged and routed traffic.	Ensures differentiated service treatment for traffic traversing bridge domains, maintaining consistent QoS handling between L2 and L3 segments.
Bridged Virtual Interface two-pass QoS	Describes how the router performs two independent QoS inspections: one at the Layer 2 bridge-domain ingress and a second at the Layer 3 BVI ingress. Covers supported classification and marking actions and how traffic transitions from bridging to routing using the two-pass model.	Provides consistent QoS treatment for traffic moving from Layer 2 to Layer 3, improves accuracy of classification and marking, and enables more flexible policy design for bridged-to-routed flows.

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