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Troubleshooting
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7.
Troubleshooting
7.1.
Troubleshooting
7.1.1.
Multiple Routes Exists in the Network where this Product is Installed
This section explains the points to consider when there are multiple routes from the PC perspective. This product
checks the consistency of going and returning packets in TCP communication. For this reason, if there is no packet
going back and forth, the TCP session is disconnected.
An example is shown in the figure below. The operation mode is bridge mode.
This product checks the packet and TCP status. In case of 1 to 4 below, since this product does not detect TCP SYN
and ACK, it considers it an illegal packet and will discard TCP ACK.
In such a case, the routing setting of the router need to be changed so as not to issue a route change request, or to
add routing information to the routing table of each PC.
1.
Since TCP SYN from PC 1 to Server is a different subnet, it is sent to RouterA of the default gateway. RouterA
forwards it to RouterB according to the routing table.
2.
RouterA issues a path change request to PC1 because PC1 and RouterB are on the same subnet.
3.
TCP SYN and ACK from Server to PC1 are sent to PC1 without going through RouterA.
4.
TCP ACK from PC1 to Server is discarded as this packet is an illegal packet.