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How To Enable And Configure Mirroring In EXOS

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TitleHow To Enable And Configure Mirroring In EXOS
This article outlines how to create and configure port or VLAN traffic mirrors in EXOS
  • EXOS
1. Create the Mirror​:
create mirror <MIRROR_NAME>
2. Define the Monitor port (the destination port to which the copied traffic should be sent):
configure mirror <MIRROR_NAME> to <PORT or PORT-LIST>
3. Define the source port(s) OR the VLAN from which the mirrored traffic will be copied.  The following outlines the two approaches:
  • Port mirroring: By default, a port mirror copies traffic in both directions.  However, additional mirroring filters can be specified to manipulate what traffic is mirrored:
configure mirror <MIRROR_NAME> add port <PORT or PORT-LIST> <filter>
  anomaly             mirror detected anomaly traffic (this would be any anomalies reported from the "show port <port> anomaly" command output
  egress              mirror egress traffic only
  ingress             mirror ingress traffic only
  ingress-and-egress  mirror all forwarded traffic (default)
  vlan                VLAN (this is identical to the VLAN filter explained below)
  • VLAN mirroring:  A VLAN mirror will only copy traffic in the ingress direction.  Like the port mirror, additional filters can be specified to manipulate what traffic is mirrored:
configure mirror <MIRROR_NAME> add vlan <VLAN_NAME> <filter>

  ingress         mirror ingress traffic arriving in a particular VLAN from any ports belonging to that VLAN
  port            mirror ingress traffic arriving on a specific port belonging to that VLAN
4. Enable the mirror:
enable mirror <MIRROR_NAME>
5. Verify the configuration is correct.  In the following sample output, the configured mirror is called M1 and it is mirroring traffic from port 1 and also from VLAN Default and forwarding it to port 10
show configuration | include mirror 

create mirror "M1" 
configure mirror M1 to port 10 
configure mirror M1 add port 1 ingress-and-egress
configure mirror M1 add vlan Default port 1 ingress
enable mirror M1
show mirror "m1"

M1   (Enabled)
    Mirror to port: 10
    Source filter instances used :  2
        Port 1, all vlans, ingress and egress
        Port 1, vlan Default, ingress only

Mirrors defined:          2
Mirrors enabled:          1 (Maximum 4)
HW filter instances used: 2 (Maximum 128)
HW mirror instances used: 1 ingress, 1 egress (Maximum 4 total, 2 egress)
Additional notes
  • To remove ports or VLANs from a mirror:
configure mirror <MIRROR_NAME> delete [all | vlan <VLAN_NAME> | port <PORT> | vlan <VLAN_NAME> port <PORT> | port <PORT> vlan <VLAN_NAME>]
  • To disable a Mirror:
disable mirror <MIRROR_NAME> | all
  • The Ingress-and-egress and egress options are only available for port-based mirroring.
  • Mirroring is done in hardware and has no impact on the CPU
  • Untagged frames may be seen with 802.1q tags in the mirrored traffic. This is because all frames are given an internal tag when they enter the switch, even if they are received untagged or are to be transmitted untagged
  • In 15.3 and earlier, only 1 mirroring instance was available (the DefaultMirror) therefore the create mirror command was not available in these versions
  • The monitor port should be defined (see step 2 above) or with the "enable mirroring to <port>" command before any filters can be configured
  • In EXOS 16.2, functionality to enable/disable the mirroring of CPU-forwarded traffic was added.  This allows for packets originating from the CPU to be included/excluded from a capture.  By default, it is disabled, which means any traffic like IGMP membership queries, LLDP exchanges, etc originating from the CPU will not be included in the capture by default and it will appear as so egress traffic is not being captured
debug vlan show mirror
  CPU forwarded packets mirroring: Disabled (Default)
  • If mirroring of CPU-forwarded traffic is required, this can be enabled with the following:
debug vlan configure mirror cpu-forwarded-packets on




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