You will need to click the Graph 1 button again to enable the graph to use this filter. This is the same display filter you created in Wireshark Lab 30: Add a "TCP Delay" Button. In the Filter area of Graph 1, enter the following filter: To make this graph more usable, we will add a filter to remove acceptable delays from view. If you look at that packet (Packet 155), this is a TCP FIN packet. Notice the value in the TCP Delta column-15.757807 seconds. The graph indicates that there is a spike in the RTT values around 25 seconds into the trace file.Ĭlick on this high point in the graph and Wireshark will jump to that packet in the main Wireshark We willįirst work without a filter at this time.Ĭlick the Graph 1 button to graph your results. Select the MAX(*) Graph 1 Calc option and enter tcp.time_delta in the Calc area. In the Y Axis Unit area, select Advanced. Locate TCP conversation delays in a trace file. You can use Wireshark's Advanced IO Graph to graph the maximum tcp.time_delta value to Next we will create an Advanced IO Graph to detect TCP delays in a trace file. These two filter expression buttons can be used to quickly identify high path latency.
Your TCP Delta column illustrates the time between each of these packets in each of the TCPĬlick Clear to remove your filter before continuing.Ĭonsider saving two filter expression buttons-one for the first two packets of the handshake andĪnother for the second and third packet of the handshake. Now you should see only the SYN/ACK and ACK packets of the handshakes in the traceįile. =0 to remove these packets from view.Įnhance your filter with these two additional conditions: Relative Sequence Number and Relative Acknowledgment Number values. These FIN packets are also being displayed because of the We canĪdd & tcp.len=0 to our filter to remove these packets from view. Relative sequence number value is 1 and the Relative Acknowledgment Number value is 1. Our filter is displaying this packet because the Is the first HTTP command sent after the handshake. There are several packetsįor example, Packets 14 and 15 are the second and third packets of the TCP handshake, but Packet 16 (=1 & =1) || (tcp.seq=1 &Ĭlick Apply and examine the results. In the display filter area, enter the following filter: These are the packets we would use to determine RTT when The time from the TCP SYN from port 35,622 and the SYN/ACK to that same port, RTT is about 17Īlthough this trace file was captured at the client, we will use it to practice locating the second and Packetģ and Packet 4 are the first two packets of a new TCP connection. The first two packets are sent from the client port 35,621. In the display filter area, enter the filter =1 and click Apply.įifty-eight packets match this filter. Let's test the filter for the first two packets of the TCP handshake and then test our filter for the last (=1) || (tcp.seq=1 & tcp.ack=1) Wireshark Lab 32: Obtain RTT using Display Filters Putting together what we've already done, we can filter on the following:
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