diff --git a/htsim/sim/atlahs_htsim_api.cpp b/htsim/sim/atlahs_htsim_api.cpp
index 0da4788..33f924a 100644
--- a/htsim/sim/atlahs_htsim_api.cpp
+++ b/htsim/sim/atlahs_htsim_api.cpp
@@ -31,10 +31,8 @@ void AtlahsHtsimApi::Send(const SendEvent &event, graph_node_properties elem) {
 
     
 
-    if (getNumberNic() > 1) {
-        from = getHtsimNodeNumber(from, elem.nic);
-        to = getHtsimNodeNumber(to, elem.nic);
-    }
+    from = getHtsimNodeNumber(from, elem.nic);
+    to = getHtsimNodeNumber(to, elem.nic);
 
     simtime_picosec flow_duration = size * 8 / 200 * 1000;
 
@@ -160,4 +158,4 @@ void AtlahsHtsimApi::EventFinished(const EventOver &event) {
     } else {
         abort();
     }
-}
\ No newline at end of file
+}
diff --git a/htsim/sim/atlahs_htsim_api.h b/htsim/sim/atlahs_htsim_api.h
index 2d5b4f7..b0c8f17 100644
--- a/htsim/sim/atlahs_htsim_api.h
+++ b/htsim/sim/atlahs_htsim_api.h
@@ -49,6 +49,11 @@ class FlowInfo {
 
 class AtlahsHtsimApi : public AtlahsApi {
 public:
+    enum class GoalRankMapping {
+        GpuRank,
+        UniqueNic,
+    };
+
     AtlahsHtsimApi() = default;
     virtual ~AtlahsHtsimApi() = default;
     
@@ -121,6 +126,37 @@ class AtlahsHtsimApi : public AtlahsApi {
     void setNumberNic(int nic) { number_nics = nic; }
     int getNumberNic() const { return number_nics; }
 
+    void setGoalRankMapping(GoalRankMapping mapping) { goal_rank_mapping = mapping; }
+    GoalRankMapping getGoalRankMapping() const { return goal_rank_mapping; }
+
+    void setGoalRankMappingFromBinaryHeader(uint32_t rank_count, int cpu_count, int nic_count) {
+        setNumberNic(nic_count);
+
+        // The binary GOAL format does not store the generator version. Infer
+        // the layout from the parsed schedule header instead: V1 unique-nic
+        // files keep ranks at node granularity and use several NICs per rank,
+        // while V2 files keep ranks at GPU/HTSIM-node granularity.
+        const bool looks_like_v2_gpu_rank =
+            nic_count == 1 ||
+            (nic_count == 2 && rank_count > static_cast<uint32_t>(nic_count) && cpu_count <= 8);
+        goal_rank_mapping =
+            looks_like_v2_gpu_rank ? GoalRankMapping::GpuRank : GoalRankMapping::UniqueNic;
+    }
+
+    bool usesUniqueNicRankMapping() const {
+        return goal_rank_mapping == GoalRankMapping::UniqueNic;
+    }
+
+    const char* getGoalRankMappingName() const {
+        switch (goal_rank_mapping) {
+            case GoalRankMapping::UniqueNic:
+                return "unique-nic";
+            case GoalRankMapping::GpuRank:
+                return "gpu-rank";
+        }
+        return "unknown";
+    }
+
     void setNumberNacks(int nacks) { number_of_nacks += nacks; }
     uint64_t getNumberNacks() const { return number_of_nacks; }
 
@@ -128,7 +164,7 @@ class AtlahsHtsimApi : public AtlahsApi {
     simtime_picosec getGlobalTimeNs() const { return _eventlist->now() / 1000; }
 
     int getHtsimNodeNumber(int lgs_host, int lgs_nic) {
-        return lgs_host * number_nics + lgs_nic;
+        return usesUniqueNicRankMapping() ? lgs_host * number_nics + lgs_nic : lgs_host;
     }
 
     linkspeed_bps linkspeed; // TO DO
@@ -158,6 +194,7 @@ class AtlahsHtsimApi : public AtlahsApi {
 
     // LGS Specific
     int number_nics = 1;
+    GoalRankMapping goal_rank_mapping = GoalRankMapping::GpuRank;
 
     // EQDS Specific 
     vector<EqdsPullPacer*> pacersEQDS;
@@ -179,4 +216,4 @@ class AtlahsHtsimApi : public AtlahsApi {
     std::function<std::unique_ptr<UecMultipath>()> mp_factory = nullptr;
 };
 
-#endif // ATLAHS_HTSIM_API_H
\ No newline at end of file
+#endif // ATLAHS_HTSIM_API_H
diff --git a/htsim/sim/logsim-interface.cpp b/htsim/sim/logsim-interface.cpp
index 81550ad..59de43f 100644
--- a/htsim/sim/logsim-interface.cpp
+++ b/htsim/sim/logsim-interface.cpp
@@ -392,6 +392,14 @@ int start_lgs(std::string filename_goal, LogSimInterface &lgs) {
     const uint p = parser.schedules.size();
     const int ncpus = parser.GetNumCPU();
     const int nnics = parser.GetNumNIC();
+    lgs_interface->htsim_api->setGoalRankMappingFromBinaryHeader(
+        static_cast<uint32_t>(p), ncpus, nnics);
+    printf("[ATLAHS] GOAL rank mapping: %s (LGS ranks=%u, CPUs=%d, NICs=%d, HTSIM nodes=%u)\n",
+           lgs_interface->htsim_api->getGoalRankMappingName(),
+           p,
+           ncpus,
+           nnics,
+           lgs_interface->htsim_api->usesUniqueNicRankMapping() ? p * nnics : p);
     bool comm_dep_file_arg = false;
 
     
@@ -509,7 +517,6 @@ int start_lgs(std::string filename_goal, LogSimInterface &lgs) {
     bool comm_dep_file_given = false;
     bool qstat_arg = false; 
     bool batchmode_given = false;
-    lgs_interface->htsim_api->setNumberNic(nnics);
     bool progress_given = true;