Port Mirroring Configuration

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Table of Contents

Table of Contents
Chapter 1 Port Mirroring Configuration........................................................................................................1

1.1 Configuring Port Mirroring Task List.............................................................................................. 1
1.2 Configuring Port Mirroring Task......................................................................................................1

1.2.1 Configuring port mirroring....................................................................................................1
1.2.2 Displaying port mirroring information.................................................................................2

1.3 Remote Mirroring Configuration Example.................................................................................... 2

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Port Mirroring Configuration

Chapter 1 Port Mirroring Configuration

1.1 Configuring Port Mirroring Task List
 Configuring port mirroring

 Displays port mirroring information

1.2 Configuring Port Mirroring Task

1.2.1 Configuring port mirroring

In order to make switch management easy, you can set port mirror and use a port of the
switch to observe the flux that runs through a group of ports.

Port mirroring could be divided like local mirroring and remote mirroring. Local mirroring
means copying message to this device’s port, and remote mirroring function means
transferring message to remote device across multiple network devices. Port mirroring
is configured by the way of mirroring group, and relative concepts include port,
destination port, remote mirroring VLAN, remote mirroring TPID, VLAN
DISABLE-LEARNING and etc.

In the remote mirroring, the local device would add a vlan tag in the mirroring message.
Messages from different mirroring’s remote groups are detected by setting the tag’s vid
(remote mirroring vlan) and tpid. In order to achieve remote mirroring function, it is
required that the middle device could transfer messages within remote mirroring’s vlan
to remote device.

Remote mirroring’s schemetic plot is like following:

Configuring remote mirroring function on source device, and mirroring source port’s
message to the output port while adding configuring RSPAN TAG on the message. Vlan
id in this tag is the remote mirroring VLAN. Middle device transfer mirroring message to
the destination port by broadcasting. The destination device transfer message from

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Port Mirroring Configuration

destination port to data monitoring device by configuration. If the destination device
supports port mirroring function, the message could be transferred from destination port
to data monitoring device by configuring local mirroring. If the destination device
supports the configuration of mac address learning based on vlan, the message could
be transferred to data monitoring device by shutting down remote mirroring vlan
address learning. If the destination device’s qos policy mapping supports the matching
of vlan, the message could be transferred to monitoring device by qos policy mapping.

Enter the EXEC mode and perform the following steps to configure port mirroring:

Command Purpose

config Enters the global configuration mode.

mirror session session_number {destination To set port mirror, run this command.
{interface interface-id} { rspan vid tpid} |

session-number is the number of the port
source {interface interface-id [, | -] rx | tx |

mirroring.
both] }

destination is the destination port of the
mirroring.

VID is the tag of remote mirroring

TPID is the tag of remote mirroring

source is the source port of mirroring.

rx means the data flow of mirroring. rx means
the input data of mirroring. tx means the output
data of mirroring, both means both mirroring

exit Goes back to the EXEC mode.

write Saves the settings.

1.2.2 Displaying port mirroring information

To display the configuration information about port mirroring, run the following
command:

Command Purpose

show mirror [session session_number] Displays the configuration information about
port mirroring session-number means the
number of the port mirroring.

1.3 Remote Mirroring Configuration Example
The network topology is shown in the following figure:

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Port Mirroring Configuration

You need to monitor the traffic of interface g0/1 on switch a and interface g0/1 on switch
b by the network analysis meter.

Configure as follows by the remote mirroring:

switch a：

mirror session 1 destination interface g0/3 rspan 100 0x8100

mirror session 1 source interface g0/1 both

switch b：

mirror session 1 destination interface g0/3 rspan 1000 0x8100

mirror session 1 source interface g0/1 both

switch c：

interface GigaEthernet0/1

switchport mode trunk

!

interface GigaEthernet0/2

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Port Mirroring Configuration

switchport mode trunk

!

interface GigaEthernet0/3

switchport mode trunk

!

!

vlan 1,100,1000

!

switch d：

mirror session 1 destination interface g0/2

mirror session 1 source interface g0/1 both

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