Reference Guide

Remote port monitoring
Remote port monitoring allows you to monitor ingress and/or egress traffic on multiple source ports of multiple devices and
forward the monitored traffic to multiple destination ports on different remote devices. Remote port monitoring helps network
administrators monitor and analyze traffic to troubleshoot network problems in a time-saving and efficient way.
In a remote port monitoring session, monitored traffic is tagged with a VLAN ID and switched on a user-defined, non-routable L2
VLAN. The VLAN is reserved in the network to carry only monitored traffic, which is forwarded on all egress ports of the VLAN.
You must configure each intermediate switch that participates in the transport of monitored traffic with the reserved L2 VLAN.
Remote port monitoring supports monitoring sessions in which multiple source and destination ports distribute across multiple
network devices.
Session and VLAN requirements
Remote port monitoring requires a source session (monitored ports on different source devices), a reserved tagged VLAN
for transporting monitored traffic (configured on source, intermediate, and destination devices), and a destination session
(destination ports connected to analyzers on destination devices).
● Configure any network device with source ports and destination ports and enable it to function in an intermediate transport
session for a reserved VLAN at the same time for multiple remote port monitoring sessions. Enable and disable individual
monitoring sessions.
● A remote port monitoring session mirrors monitored traffic by prefixing the reserved VLAN tag to monitored packets to
transmit using the reserved VLAN.
● The source address, destination address, and original VLAN ID of the mirrored packet are prefixed with the tagged VLAN
header. Untagged source packets are tagged with the reserved VLAN ID.
● The member port of the reserved VLAN must have the MTU and IPMTU value as MAX+4 (to hold the VLAN tag parameter).
● To associate with source session, the reserved VLAN can have a maximum of four member ports.
● To associate with destination session, the reserved VLAN can have multiple member ports.
● The reserved VLAN cannot have untagged ports.
Reserved L2 VLAN
● MAC address learning in the reserved VLAN is automatically disabled.
● There is no restriction on the VLAN IDs used for the reserved remote monitoring VLAN. Valid VLAN IDs are from 2 to 4093.
The default VLAN ID is not supported.
● In monitored traffic, packets that have the same destination MAC address as an intermediate or destination device in the
path used by the reserved VLAN to transport the mirrored traffic are dropped by the device that receives the traffic if the
device has a L3 VLAN configured.
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Layer 2