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Community Member

ERSPAN on Nexus 5596 (HSRP pair)


I hope all are well and can pls help / advise with the following

We have HSRP between NexusA and NexusB with access layer switches connecting to the core using VPC

We are trying to setup a VAM  server Voice recording for Siemens phones.

We need to span all voice vlan and point it to the VAM server the VAM server connects to a 3750 Stack considering the amount of traffic multiple span session can generate I plan to move the server to the Nexus directly and run a Local Span Session.   (Is that a good idea ?)

My Question is

1>  As we have two Nexus running HSRP and VAM server only connects physically to one NexusA (I can run local span on that nexusA)  the Second NexusB is not directly connected to the VAM server I plan to run ERSPAN can you please confirm if this is the best design and which path will the span traffic take from Nexus B to NexusA will it go through the access layer switches depending on the vlans allowed on the uplinks or will it go through the 20 Gig uplink between the two Nexus allowing all vlans (VPN peer links) ?

WE have approximatley 10 voice vlans

Do we an example config for ERSPAN session where the source are vlans (As I am for fimilliar with RSPAN) ?

Thanks in advance


VIP Super Bronze

Re: ERSPAN on Nexus 5596 (HSRP pair)


I plan to move the server to the Nexus directly and run a Local Span Session.   (Is that a good idea ?)

That should work fine, because:

When data rate is above 5Gbps, SPAN traffic is reduced to 0.75Gbps to avoid potential congestion over the link between ingress port and switch fabric

The aggregate SPAN traffic from all SPAN sources (including both RX and TX SPAN) can‘t exceed 5Gbps per UPC

SPAN traffic won‘t affect data traffic when SPAN destination port is congested

Also, here is the config guide for ERSPAN:


Community Member

Re: ERSPAN on Nexus 5596 (HSRP pair)

Thanks Reza,

I have managed to setup the source session

Below is out out on nexus 1

HS-SR1-N5K-2# sh monitor session all

   session 6


type              : erspan-source

state             : up

erspan-id         : 100

vrf-name          : default

destination-ip    :

ip-ttl            : 255

ip-dscp           : 0

origin-ip         : (global)

source intf       :

    rx            :

    tx            :

    both          :

source VLANs      :

    rx            : 726,766

Nexus 2 is where I have my voip recorder connected

Do you how to configure a ERSPAN for a destination interface here  (reading the URL above it states the Nexus 5K does not support Destination ERSPAN do you of a way I can get round this one) ?

With 6500 we normally use RSPAN can we do some simillar with Nexus 5K

Kind Regards,


Community Member

Re: ERSPAN on Nexus 5596 (HSRP pair)

Cisco Experts can you please help with teh ERSPAN on Nexus

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