When TCP sends a packet or a group of packets (refer to the How it works... section at the end of this recipe), it waits for an acknowledgment to confirm the acceptance of these packets. Retransmissions obviously happen due to a packet that has not arrived, or an acknowledgment that has not arrived on time. There can be various reasons for this, and finding the correct reason is the goal of this recipe.
Troubleshooting TCP retransmission issues
Getting ready
When you see that the network becomes slow, one of the reasons for this can be retransmissions. Connect Wireshark in the port mirror to the suspicious client or server, and watch the results.
In this recipe, we will see some common problems that we may encounter with Wireshark...
