Traffic Mirroring Configuration Guide for Cisco 8000 Series Routers, Cisco IOS XR Release

PDF

Traffic mirroring

Updated: March 2, 2026

Want to summarize with AI?

Log in

Overview

This topic explains traffic mirroring, a feature that monitors Layer 3 network traffic by directing copies to an analyzer without impacting performance. It outlines key terminology, configuration guidelines, and various mirroring types, including ERSPAN and local SPAN, to facilitate comprehensive network monitoring and analysis.

Traffic mirroring or port mirroring is a network monitoring feature that

  • monitors Layer 3 network traffic passing in or out of Ethernet interfaces

  • directs this traffic to a network analyzer for analysis, and

  • operates as a proprietary function under Cisco Switched Port Analyzer (SPAN).

Table 1. Feature History Table

Feature Name

Release Information

Feature Description

Traffic Mirroring

 Release 25.1.1

Introduced in this release on: Fixed Systems (8010 [ASIC: A100])

Traffic mirroring, also known as port mirroring or Switched Port Analyzer (SPAN), is a proprietary feature by Cisco. It allows the monitoring of Layer 3 network traffic that enters or exits a set of Ethernet interfaces. This mirrored traffic can then be directed to a network analyzer for further analysis.

This feature is now supported on:

  • 8011-4G24Y4H-I

Benefits of traffic mirroring

Traffic mirroring allows you to

  • monitor Layer 3 network traffic

  • analyze traffic using a network analyzer, and

  • mirror traffic without affecting the switching of traffic on source interfaces.