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Some Packets Fail to Be Passed When EFS0 of OSN 3500 Is Interconnected with the Mirroring Port of S3900

Publication Date:  2019-07-10 Views:  165 Downloads:  0

Issue Description

Networking diagram


The S3900 sends packets that are sent and received between the S3900 and the server to OSN 3500 through the mirroring port, and then OSN 3500 sends the packets to the detection software through the private line service channel of the OSN 3500. The detection software can detect the packets sent from the S3900 to the server, but cannot detect the packets received from the server.




Alarm Information

None

Handling Process

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.





Root Cause

None

Solution

Set the TAG attribute of the external port on the EFS0 board of the OSN 3500 to Hybrid, or disable the entry detection function.

END