Knowledge Base
Last Updated: 2026-07-02
Port 13400 is the default destination engineers look for when narrowing Wireshark captures down to Diagnostic over IP traffic.
Start with tcp.port == 13400 || udp.port == 13400 to isolate the core DoIP traffic lanes before inspecting individual payload types.
Once the transport stream is isolated, focus on routing activation, vehicle identification, and UDS request or response sequences rather than scanning the full capture blindly.
After transport filtering, check whether the capture shows vehicle announcement traffic, routing activation, and then the diagnostic requests that matter to your failure point.
If the flow jumps between multiple source addresses or sessions, separate the tester-to-gateway path from ECU-specific traffic before drawing conclusions.
Raw packet views still require manual stitching across timing gaps, retransmissions, and mixed session traffic.
That is the point where a structured analyzer becomes more efficient than handcrafted filters alone.
If you already know the port but still cannot tell which request triggered the failure, the bottleneck is no longer filtering. It is session reconstruction.
That is the handoff point where uploading the original capture is faster than building more custom Wireshark display rules.
These examples are drawn from real capture files available in the project evidence pool. They give the article something stronger than generic protocol theory.
Connection opens, routing activates, then the session is closed anyway
Evidence reference: EVID-PORT13400-VCI-DISCONNECT-01
Node roles in this case
A compact field capture where the transport setup succeeds but the session is still lost immediately afterward.
Evidence signals
Timeline
For the Wireshark port-13400 search intent, this is the exact moment where port filtering stops being enough and state reconstruction begins.
These are the interpretation traps that real packet evidence helps avoid.
Use nearby guides to move from protocol filtering to root-cause troubleshooting without leaving the knowledge base.
Start with tcp.port == 13400 || udp.port == 13400. That isolates the default DoIP transport lanes before deeper payload inspection.
Because the real bottleneck is usually reconstructing session order, identifying the failing request, and separating overlapping exchanges.
Best for engineers who already know the port but still cannot reconstruct the failing exchange.
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