How to configure ERSPAN on Cisco Nexus Switches

Encapsulated Remote Switched Port Analyzer (ERSPAN) is a technique to mirror traffic over L3 network. Traffic will be encapsulated at the source end and then decapsulated at the destination end. In this lesson, we will learn to configure ERSPAN in Nexus switches.

Network Topology

I will present very sample configuration based on below topology. Hope it will be helpful.

How to configure ERSPAN on Cisco Nexus Switches 2
Figure: Topology for ERSPAN Lab

Let’s set a Goal

  • Need to capture traffic from interface e1/2 on NX-01 switch.
  • But that capture need to happen from e2/4 interface on switch NX-02.

Configuration of ERSPAN

Let’s configure source switch (NX-01), based on Cisco recommendation.

NX-01(config)# monitor session 10 type erspan-source
NX-01(config-erspan-src)# erspan-id 20
NX-01(config-erspan-src)# vrf default
NX-01(config-erspan-src)# destination ip
NX-01(config-erspan-src)# source interface ethernet e1/2 both
NX-01(config-erspan-src)# no shut
NX-01(config-erspan-src)# exit

NX-01(config)# monitor erspan origin ip-address global
Important Info
++ Erspan-ID must need to be same on the source and destination end.
++ By default “monitor session” is disabled, you need to run “no shutdown” to enable it.

Now, we will configure destination switch (NX-02).

NX-02(config)# monitor session 10 type erspan-destination
NX-02(config-erspan-dst)# erspan-id 20
NX-02(config-erspan-dst)# source ip
NX-02(config-erspan-dst)# destination interface e2/4
NX-02(config-erspan-dst)# no shut
NX-02(config-erspan-dst)# exit

Our configuration is done. Now, we need to connect an analyzer at e2/3 port on the destination switch (NX-02) and we will get the capture data.

This is how to configure ERSPAN in Nexus switches. Let me know if you have any questions.


Cisco Nexus 7000 Series NX-OS System Management Configuration Guide.

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2 thoughts on “How to configure ERSPAN on Cisco Nexus Switches”

  1. Author, please add to the article information about destination port configuration:
    interface Ethernet2/4
    description — ERSPAN —
    switchport monitor
    no shutdown

    And notice that fact: Source ip is that local ip address on the switch where ERSPAN forward to from the ERSPAN source switch.

    And please add troubleshooting command.
    After these addictions your artical will be complete useful for everyone.
    Thanks, for your job

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