3Com S7902E, Configuration Manual

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1-3
copies the packets passing through the mirroring port, broadcasts the packets in the remote probe
VLAN for remote mirroring through the egress port, and transmits the packets to the destination device
via the intermediate device. When receiving these mirrored packets, the destination device compares
their VLAN IDs to the ID of the remote probe VLAN configured in the remote destination mirroring group.
If the VLAN IDs of these mirrored packets match the remote probe VLAN ID, the device forwards them
to the data monitoring device through the monitor port. In this way, the data monitoring device
connected to the monitor port on the destination device can monitor and analyze packets passing
through the mirroring port on the source device.
z
You must ensure that the source device and the destination device can communicate at Layer 2 in
the remote probe VLAN.
z
Because packets of the mirroring port are broadcast in the remote probe VLAN created on the
source device, you can deliver the local port mirroring function by adding the other ports on the
source device to the remote probe VLAN.
z
For the mirrored packets to be forwarded to the monitor port, ensure that the same probe VLAN is
configured in the remote source and destination mirroring groups.
z
To make the port mirroring function work properly, before configuring bidirectional traffic mirroring
on a port in a mirroring group, you need to use the mac-address mac-learning disable command
on the source device, intermediate devices, and destination device to disable the MAC address
learning function for the remote port mirroring VLAN. For more information about the
mac-address mac-learning disable command, refer to MAC Address Table Management
Commands in the System Volume .
For a mirrored packet to successfully arrive at the remote destination device, you need to ensure that
the VLAN ID carried in the packet is correct (that is, the same as the probe VLAN ID). If the VLAN is
removed or the VLAN ID is changed, the Layer 2 remote port mirroring configuration becomes invalid.
Layer 3 remote port mirroring
Layer 3 remote port mirroring is implemented through the cooperation of a remote source mirroring
group, a remote destination mirroring group, and a GRE tunnel, as shown in Figure 1-3 .