1. Get packets on
the PC connected to the mirroring port. The packets sent from the S3900 to the
server do not carry VLAN tags and the packets received from the server carry
VLAN tags, as shown in the following figure.
The TAG attributes of the two ends of
the OSN 3500 on the Tx side are set to Access on the external port and Tag
Aware on the internal port. The external port with Access discards the packets
with VLAN tags and adds the default VLAN tags to the packets without VLAN tags.
2. Analyze the packets
on the mirroring port of the S3900. When mirroring the packets sent from the
S3900 to the server, the port strips the VLAN tags of the packets. When
mirroring the packets received from the server, the port adds the default VLAN
109 to the packets. The packets shown in the figures prove this.
In conclusion, when the
packets on the mirroring port are those received from the server, the packets
carrying VLAN tags are discarded by the transmit port whose TAG attribute is
access. Therefore, the detection software connected to the transmission device
cannot detect the packets received from the server.
Set the TAG attribute of
the external port on the EFS0 board of the OSN 3500 to Hybrid, or disable the
entry detection function.