Only create a sibling activity when trace id, span id or trace state differ

src/OpenTelemetry.Instrumentation.AspNetCore/Implementation/HttpInListener.cs

@@ -112,7 +112,7 @@ public void OnStartActivity(Activity activity, object payload)
         // By this time, samplers have already run and
         // activity.IsAllDataRequested populated accordingly.
 
-        HttpContext context = payload as HttpContext;
+        var context = payload as HttpContext;
         if (context == null)
         {
             AspNetCoreInstrumentationEventSource.Log.NullPayload(nameof(HttpInListener), nameof(this.OnStartActivity), activity.OperationName);
@@ -125,9 +125,11 @@ public void OnStartActivity(Activity activity, object payload)
         if (textMapPropagator is not TraceContextPropagator)
         {
             var ctx = textMapPropagator.Extract(default, request, HttpRequestHeaderValuesGetter);
-
+            var activityContext = new ActivityContext(activity.TraceId, activity.ParentSpanId, activity.ActivityTraceFlags, activity.TraceStateString, true);
             if (ctx.ActivityContext.IsValid()
-                && ctx.ActivityContext != new ActivityContext(activity.TraceId, activity.ParentSpanId, activity.ActivityTraceFlags, activity.TraceStateString, true))
+                && ((ctx.ActivityContext.TraceId != activityContext.TraceId)
+                    || (ctx.ActivityContext.SpanId != activityContext.SpanId)
+                    || (ctx.ActivityContext.TraceState != activityContext.TraceState)))
             {
                 // Create a new activity with its parent set from the extracted context.
                 // This makes the new activity as a "sibling" of the activity created by

test/OpenTelemetry.Instrumentation.AspNetCore.Tests/BasicTests.cs

@@ -19,6 +19,9 @@
 using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Hosting;
 using Microsoft.AspNetCore.Http;
+#if NET7_0_OR_GREATER
+using Microsoft.AspNetCore.Http.Features;
+#endif
 using Microsoft.AspNetCore.Mvc.Testing;
 using Microsoft.AspNetCore.TestHost;
 using Microsoft.Extensions.DependencyInjection;
@@ -1035,6 +1038,43 @@ public async Task DiagnosticSourceExceptionCallBackIsNotReceivedForExceptionsHan
         Assert.Equal(2, numberOfSubscribedEvents);
     }
 
+#if NET7_0_OR_GREATER
+    [Fact]
+    public async Task NoSiblingActivityCreatedWhenIdFormatIsW3CWithTraceFlagsNone()
+    {
+        this.tracerProvider = Sdk.CreateTracerProviderBuilder()
+            .SetSampler(new AlwaysOnSampler())
+            .AddAspNetCoreInstrumentation()
+            .Build();
+
+        var builder = WebApplication.CreateBuilder();
+        builder.WebHost.UseUrls("http://*:0");
+        var app = builder.Build();
+
+        app.MapGet("/values", (HttpContext context) =>
+        {
+            var activity = context.Features.GetRequiredFeature<IHttpActivityFeature>().Activity;
+            var equal = Activity.Current.Id == activity.Id;
+
+            return Results.Ok(equal);
+        });
+
+        _ = app.RunAsync();
+
+        var url = app.Urls.ToArray()[0];
+        var portNumber = url.Substring(url.LastIndexOf(':') + 1);
+
+        using var client = new HttpClient();
+        var req = new HttpRequestMessage(HttpMethod.Get, $"http://localhost:{portNumber}/values");
+        req.Headers.Add("traceparent", "00-0af7651916cd43dd8448eb211c80319c-b7ad6b7169203331-00");
+        var res = await client.SendAsync(req);
+        var result = bool.Parse(await res.Content.ReadAsStringAsync());
+
+        Assert.True(res.IsSuccessStatusCode);
+        Assert.True(result);
+    }
+#endif
+
     public void Dispose()
     {
         this.tracerProvider?.Dispose();