marker: serial-link (WAN) support via data_link_type -> uBridge linktype

Markers now work on serial links (Cisco HDLC / PPP / Frame Relay / ATM), not just Ethernet. A marker carries a data_link_type (default DLT_EN10MB); at the uBridge boundary it becomes the 'mark ... linktype <dlt>' keyword so the BPF compiles and the pcap is written with the matching link-layer.

- MarkerCreate / MarkerDefinitionCreate gain data_link_type (default DLT_EN10MB). Per-link it is create-only; definitions are updatable (a change re-fans-out).
- base_node._marker_linktype() normalizes the GNS3 DLT name (strip DLT_, uppercase, None for EN10MB). Single source is SerialPort.data_link_types, so Cisco PPP -> PPP_SERIAL (50), matching the capture path -- no second mapping table.
- _ubridge_add_marker_filter (generic) and the IOU marker loop append 'linktype <dlt>'.
- Definition fan-out branches on link_type in inherit_marker: Ethernet is always EN10MB; a serial link uses the definition's WAN encapsulation, or is SKIPPED when none was chosen (an EN10MB pcap on serial is undecodable). One definition covers a mixed topology.
- MCP marker_definition exposes data_link_type (None = not forwarded).
- No uBridge rebuild on a data_link_type change -- only that one marker's filter is swapped (delete + re-add), mirroring a BPF change; reset_packet_filters preserves sibling mark filters.

Requires the uBridge build with 'mark ... linktype' support.

gns3server/api/routes/controller/projects.py

@@ -271,6 +271,7 @@ async def create_marker_definition(
         direction=def_data.direction,
         color=def_data.color,
         highlight_duration=def_data.highlight_duration,
+        data_link_type=def_data.data_link_type,
     )
     return project.marker_definitions.get(name, {})
 
@@ -297,6 +298,7 @@ async def update_marker_definition(
         direction=def_data.direction if "direction" in def_data.model_fields_set else _UNSET,
         color=def_data.color,
         highlight_duration=def_data.highlight_duration,
+        data_link_type=def_data.data_link_type if "data_link_type" in def_data.model_fields_set else _UNSET,
     )
     return project.marker_definitions.get(def_name, {})
 

gns3server/api/routes/mcp/__init__.py

@@ -1052,6 +1052,7 @@ async def marker_definition(
     tag: Annotated[int | None, Field(description="Numeric tag for packet correlation")] = None,
     color: Annotated[str | None, Field(description="Hex color for UI highlight, e.g. '#ff5722'")] = None,
     highlight_duration: Annotated[int | None, Field(description="UI highlight duration in milliseconds")] = None,
+    data_link_type: Annotated[str | None, Field(description="pcap link-layer type for serial links (DLT_C_HDLC / DLT_PPP_SERIAL / DLT_FRELAY / DLT_ATM_RFC1483). Omit = Ethernet-only (serial links skipped); setting it also covers serial links with that encapsulation")] = None,
 ) -> list[dict[str, Any]]:
     """Manage project-level marker definitions — traffic-insight rules that apply to ALL links.
 
@@ -1060,7 +1061,7 @@ async def marker_definition(
     On delete, 'global-{name}' is removed from every link.
 
     Create requires: project_id, action='create', bpf
-    Update requires: project_id, action='update', def_name, and at least one of (bpf, tag, color, highlight_duration)
+    Update requires: project_id, action='update', def_name, and at least one of (bpf, tag, color, highlight_duration, data_link_type)
     Delete requires: project_id, action='delete', def_name
     List requires:  project_id, action='list'
 
@@ -1073,7 +1074,7 @@ async def marker_definition(
     Common BPF examples: 'arp', 'icmp', 'ospf', 'tcp port 22', 'udp port 53'
     """
     params = {"project_id": project_id, "action": action}
-    for opt in ("bpf", "def_name", "name", "tag", "color", "highlight_duration"):
+    for opt in ("bpf", "def_name", "name", "tag", "color", "highlight_duration", "data_link_type"):
         val = locals().get(opt)
         if val is not None:
             params[opt] = val

gns3server/api/routes/mcp/links.py

@@ -457,7 +457,7 @@ def marker_definition_handler(params: dict[str, Any], gns3_ctx: dict[str, Any])
         if not bpf:
             return {"error": "bpf is required for create action"}
         body: dict[str, Any] = {"bpf": bpf}
-        for opt in ("name", "tag", "color", "highlight_duration"):
+        for opt in ("name", "tag", "color", "highlight_duration", "data_link_type"):
             if params.get(opt) is not None:
                 body[opt] = params[opt]
         # No direction: a definition fans out to every link and auto-selects its
@@ -473,11 +473,11 @@ def marker_definition_handler(params: dict[str, Any], gns3_ctx: dict[str, Any])
 
     if action == "update":
         body = {}
-        for opt in ("bpf", "tag", "color", "highlight_duration"):
+        for opt in ("bpf", "tag", "color", "highlight_duration", "data_link_type"):
             if params.get(opt) is not None:
                 body[opt] = params[opt]
         if not body:
-            return {"error": "At least one update field is required (bpf, tag, color, highlight_duration)"}
+            return {"error": "At least one update field is required (bpf, tag, color, highlight_duration, data_link_type)"}
         return conn.http_call("put", url, json_data=body).json()
 
     # action == "delete"