diff --git a/third_party/xla/xla/service/gpu/model/collective_interpolator_test.cc b/third_party/xla/xla/service/gpu/model/collective_interpolator_test.cc
index 26cfc6a2bbb..8a4348ecf31 100644
--- a/third_party/xla/xla/service/gpu/model/collective_interpolator_test.cc
+++ b/third_party/xla/xla/service/gpu/model/collective_interpolator_test.cc
@@ -151,10 +151,10 @@ class CollectiveInterpolationTest : public TestWithParam<ParametrizedTestCase> {
       case GPUCommunicationType::SINGLE_HOST:
         iota = IotaReplicaGroupList(num_hosts, kNumGpusPerHost);
         break;
-      case GPUCommunicationType::RAIL_ALIGNED:
+      case GPUCommunicationType::MULTI_HOST_WORLD_LEVEL:
         iota = IotaReplicaGroupList(1, num_hosts * kNumGpusPerHost);
         break;
-      case GPUCommunicationType::NON_RAIL_ALIGNED:
+      case GPUCommunicationType::MULTI_HOST_NON_WORLD_LEVEL:
         iota = IotaReplicaGroupList(kNumGpusPerHost, num_hosts,
                                     {num_hosts, kNumGpusPerHost}, {1, 0});
         break;
@@ -169,56 +169,56 @@ class CollectiveInterpolationTest : public TestWithParam<ParametrizedTestCase> {
   std::vector<SpaceSpec> test_space_ = {
       {
           /*opcode=*/HloOpcode::kAllReduce,
-          /*comm=*/GPUCommunicationType::RAIL_ALIGNED,
+          /*comm=*/GPUCommunicationType::MULTI_HOST_WORLD_LEVEL,
           /*tensor_size=*/1024,
           /*num_nodes=*/2,
           /*network_througput_bytes=*/1024,
       },
       {
           /*opcode=*/HloOpcode::kAllReduce,
-          /*comm=*/GPUCommunicationType::RAIL_ALIGNED,
+          /*comm=*/GPUCommunicationType::MULTI_HOST_WORLD_LEVEL,
           /*tensor_size=*/2 * 1024,
           /*num_nodes=*/2,
           /*network_througput_bytes=*/2 * 1024,
       },
       {
           /*opcode=*/HloOpcode::kAllReduce,
-          /*comm=*/GPUCommunicationType::RAIL_ALIGNED,
+          /*comm=*/GPUCommunicationType::MULTI_HOST_WORLD_LEVEL,
           /*tensor_size=*/1024,
           /*num_nodes=*/4,
           /*network_througput_bytes=*/4 * 1024,
       },
       {
           /*opcode=*/HloOpcode::kAllReduce,
-          /*comm=*/GPUCommunicationType::RAIL_ALIGNED,
+          /*comm=*/GPUCommunicationType::MULTI_HOST_WORLD_LEVEL,
           /*tensor_size=*/2 * 1024,
           /*num_nodes=*/4,
           /*network_througput_bytes=*/5 * 1024,
       },
       {
           /*opcode=*/HloOpcode::kAllReduce,
-          /*comm=*/GPUCommunicationType::NON_RAIL_ALIGNED,
+          /*comm=*/GPUCommunicationType::MULTI_HOST_NON_WORLD_LEVEL,
           /*tensor_size=*/1024,
           /*num_nodes=*/2,
           /*network_througput_bytes=*/512,
       },
       {
           /*opcode=*/HloOpcode::kAllReduce,
-          /*comm=*/GPUCommunicationType::NON_RAIL_ALIGNED,
+          /*comm=*/GPUCommunicationType::MULTI_HOST_NON_WORLD_LEVEL,
           /*tensor_size=*/2 * 1024,
           /*num_nodes=*/2,
           /*network_througput_bytes=*/2 * 512,
       },
       {
           /*opcode=*/HloOpcode::kAllReduce,
-          /*comm=*/GPUCommunicationType::NON_RAIL_ALIGNED,
+          /*comm=*/GPUCommunicationType::MULTI_HOST_NON_WORLD_LEVEL,
           /*tensor_size=*/1024,
           /*num_nodes=*/4,
           /*network_througput_bytes=*/4 * 512,
       },
       {
           /*opcode=*/HloOpcode::kAllReduce,
-          /*comm=*/GPUCommunicationType::NON_RAIL_ALIGNED,
+          /*comm=*/GPUCommunicationType::MULTI_HOST_NON_WORLD_LEVEL,
           /*tensor_size=*/2 * 1024,
           /*num_nodes=*/4,
           /*network_througput_bytes=*/5 * 512,
@@ -253,56 +253,56 @@ class CollectiveInterpolationTest : public TestWithParam<ParametrizedTestCase> {
       },
       {
           /*opcode=*/HloOpcode::kReduceScatter,
-          /*comm=*/GPUCommunicationType::RAIL_ALIGNED,
+          /*comm=*/GPUCommunicationType::MULTI_HOST_WORLD_LEVEL,
           /*tensor_size=*/1024,
           /*num_nodes=*/2,
           /*network_througput_bytes=*/1024,
       },
       {
           /*opcode=*/HloOpcode::kReduceScatter,
-          /*comm=*/GPUCommunicationType::RAIL_ALIGNED,
+          /*comm=*/GPUCommunicationType::MULTI_HOST_WORLD_LEVEL,
           /*tensor_size=*/2 * 1024,
           /*num_nodes=*/2,
           /*network_througput_bytes=*/2 * 1024,
       },
       {
           /*opcode=*/HloOpcode::kReduceScatter,
-          /*comm=*/GPUCommunicationType::RAIL_ALIGNED,
+          /*comm=*/GPUCommunicationType::MULTI_HOST_WORLD_LEVEL,
           /*tensor_size=*/1024,
           /*num_nodes=*/4,
           /*network_througput_bytes=*/4 * 1024,
       },
       {
           /*opcode=*/HloOpcode::kReduceScatter,
-          /*comm=*/GPUCommunicationType::RAIL_ALIGNED,
+          /*comm=*/GPUCommunicationType::MULTI_HOST_WORLD_LEVEL,
           /*tensor_size=*/2 * 1024,
           /*num_nodes=*/4,
           /*network_througput_bytes=*/5 * 1024,
       },
       {
           /*opcode=*/HloOpcode::kReduceScatter,
-          /*comm=*/GPUCommunicationType::NON_RAIL_ALIGNED,
+          /*comm=*/GPUCommunicationType::MULTI_HOST_NON_WORLD_LEVEL,
           /*tensor_size=*/1024,
           /*num_nodes=*/2,
           /*network_througput_bytes=*/512,
       },
       {
           /*opcode=*/HloOpcode::kReduceScatter,
-          /*comm=*/GPUCommunicationType::NON_RAIL_ALIGNED,
+          /*comm=*/GPUCommunicationType::MULTI_HOST_NON_WORLD_LEVEL,
           /*tensor_size=*/2 * 1024,
           /*num_nodes=*/2,
           /*network_througput_bytes=*/2 * 512,
       },
       {
           /*opcode=*/HloOpcode::kReduceScatter,
-          /*comm=*/GPUCommunicationType::NON_RAIL_ALIGNED,
+          /*comm=*/GPUCommunicationType::MULTI_HOST_NON_WORLD_LEVEL,
           /*tensor_size=*/1024,
           /*num_nodes=*/4,
           /*network_througput_bytes=*/4 * 512,
       },
       {
           /*opcode=*/HloOpcode::kReduceScatter,
-          /*comm=*/GPUCommunicationType::NON_RAIL_ALIGNED,
+          /*comm=*/GPUCommunicationType::MULTI_HOST_NON_WORLD_LEVEL,
           /*tensor_size=*/2 * 1024,
           /*num_nodes=*/4,
           /*network_througput_bytes=*/5 * 512,
@@ -337,56 +337,56 @@ class CollectiveInterpolationTest : public TestWithParam<ParametrizedTestCase> {
       },
       {
           /*opcode=*/HloOpcode::kAllGather,
-          /*comm=*/GPUCommunicationType::RAIL_ALIGNED,
+          /*comm=*/GPUCommunicationType::MULTI_HOST_WORLD_LEVEL,
           /*tensor_size=*/1024,
           /*num_nodes=*/2,
           /*network_througput_bytes=*/1024,
       },
       {
           /*opcode=*/HloOpcode::kAllGather,
-          /*comm=*/GPUCommunicationType::RAIL_ALIGNED,
+          /*comm=*/GPUCommunicationType::MULTI_HOST_WORLD_LEVEL,
           /*tensor_size=*/2 * 1024,
           /*num_nodes=*/2,
           /*network_througput_bytes=*/2 * 1024,
       },
       {
           /*opcode=*/HloOpcode::kAllGather,
-          /*comm=*/GPUCommunicationType::RAIL_ALIGNED,
+          /*comm=*/GPUCommunicationType::MULTI_HOST_WORLD_LEVEL,
           /*tensor_size=*/1024,
           /*num_nodes=*/4,
           /*network_througput_bytes=*/4 * 1024,
       },
       {
           /*opcode=*/HloOpcode::kAllGather,
-          /*comm=*/GPUCommunicationType::RAIL_ALIGNED,
+          /*comm=*/GPUCommunicationType::MULTI_HOST_WORLD_LEVEL,
           /*tensor_size=*/2 * 1024,
           /*num_nodes=*/4,
           /*network_througput_bytes=*/5 * 1024,
       },
       {
           /*opcode=*/HloOpcode::kAllGather,
-          /*comm=*/GPUCommunicationType::NON_RAIL_ALIGNED,
+          /*comm=*/GPUCommunicationType::MULTI_HOST_NON_WORLD_LEVEL,
           /*tensor_size=*/1024,
           /*num_nodes=*/2,
           /*network_througput_bytes=*/512,
       },
       {
           /*opcode=*/HloOpcode::kAllGather,
-          /*comm=*/GPUCommunicationType::NON_RAIL_ALIGNED,
+          /*comm=*/GPUCommunicationType::MULTI_HOST_NON_WORLD_LEVEL,
           /*tensor_size=*/2 * 1024,
           /*num_nodes=*/2,
           /*network_througput_bytes=*/2 * 512,
       },
       {
           /*opcode=*/HloOpcode::kAllGather,
-          /*comm=*/GPUCommunicationType::NON_RAIL_ALIGNED,
+          /*comm=*/GPUCommunicationType::MULTI_HOST_NON_WORLD_LEVEL,
           /*tensor_size=*/1024,
           /*num_nodes=*/4,
           /*network_througput_bytes=*/4 * 512,
       },
       {
           /*opcode=*/HloOpcode::kAllGather,
-          /*comm=*/GPUCommunicationType::NON_RAIL_ALIGNED,
+          /*comm=*/GPUCommunicationType::MULTI_HOST_NON_WORLD_LEVEL,
           /*tensor_size=*/2 * 1024,
           /*num_nodes=*/4,
           /*network_througput_bytes=*/5 * 512,
@@ -428,14 +428,14 @@ class CollectiveInterpolationTest : public TestWithParam<ParametrizedTestCase> {
       },
       {
           /*opcode=*/HloOpcode::kAllToAll,
-          /*comm=*/GPUCommunicationType::RAIL_ALIGNED,
+          /*comm=*/GPUCommunicationType::MULTI_HOST_WORLD_LEVEL,
           /*tensor_size=*/1024,
           /*num_nodes=*/2,
           /*network_througput_bytes=*/2048,
       },
       {
           /*opcode=*/HloOpcode::kAllToAll,
-          /*comm=*/GPUCommunicationType::NON_RAIL_ALIGNED,
+          /*comm=*/GPUCommunicationType::MULTI_HOST_NON_WORLD_LEVEL,
           /*tensor_size=*/1024,
           /*num_nodes=*/2,
           /*network_througput_bytes=*/4096,
@@ -459,7 +459,7 @@ INSTANTIATE_TEST_SUITE_P(
             {
                 /*opcode=*/HloOpcode::kAllReduce,
                 /*comm=*/
-                GPUCommunicationType::RAIL_ALIGNED,
+                GPUCommunicationType::MULTI_HOST_WORLD_LEVEL,
                 /*tensor_size=*/1024,
                 /*num_nodes=*/2,
             },
@@ -471,7 +471,7 @@ INSTANTIATE_TEST_SUITE_P(
             {
                 /*opcode=*/HloOpcode::kAllReduce,
                 /*comm=*/
-                GPUCommunicationType::RAIL_ALIGNED,
+                GPUCommunicationType::MULTI_HOST_WORLD_LEVEL,
                 /*tensor_size=*/1024,
                 /*num_nodes=*/8,
             },
@@ -483,7 +483,7 @@ INSTANTIATE_TEST_SUITE_P(
             {
                 /*opcode=*/HloOpcode::kAllReduce,
                 /*comm=*/
-                GPUCommunicationType::RAIL_ALIGNED,
+                GPUCommunicationType::MULTI_HOST_WORLD_LEVEL,
                 /*tensor_size=*/4 * 1024,
                 /*num_nodes=*/2,
             },
@@ -495,7 +495,7 @@ INSTANTIATE_TEST_SUITE_P(
             {
                 /*opcode=*/HloOpcode::kAllReduce,
                 /*comm=*/
-                GPUCommunicationType::RAIL_ALIGNED,
+                GPUCommunicationType::MULTI_HOST_WORLD_LEVEL,
                 /*tensor_size=*/1024,
                 /*num_nodes=*/3,
             },
@@ -507,7 +507,7 @@ INSTANTIATE_TEST_SUITE_P(
             {
                 /*opcode=*/HloOpcode::kAllReduce,
                 /*comm=*/
-                GPUCommunicationType::RAIL_ALIGNED,
+                GPUCommunicationType::MULTI_HOST_WORLD_LEVEL,
                 /*tensor_size=*/1024 + 256,
                 /*num_nodes=*/2,
             },
@@ -519,7 +519,7 @@ INSTANTIATE_TEST_SUITE_P(
             {
                 /*opcode=*/HloOpcode::kAllReduce,
                 /*comm=*/
-                GPUCommunicationType::NON_RAIL_ALIGNED,
+                GPUCommunicationType::MULTI_HOST_NON_WORLD_LEVEL,
                 /*tensor_size=*/1024,
                 /*num_nodes=*/2,
             },
@@ -531,7 +531,7 @@ INSTANTIATE_TEST_SUITE_P(
             {
                 /*opcode=*/HloOpcode::kAllReduce,
                 /*comm=*/
-                GPUCommunicationType::NON_RAIL_ALIGNED,
+                GPUCommunicationType::MULTI_HOST_NON_WORLD_LEVEL,
                 /*tensor_size=*/1024,
                 /*num_nodes=*/8,
             },
@@ -543,7 +543,7 @@ INSTANTIATE_TEST_SUITE_P(
             {
                 /*opcode=*/HloOpcode::kAllReduce,
                 /*comm=*/
-                GPUCommunicationType::NON_RAIL_ALIGNED,
+                GPUCommunicationType::MULTI_HOST_NON_WORLD_LEVEL,
                 /*tensor_size=*/4 * 1024,
                 /*num_nodes=*/2,
             },
@@ -555,7 +555,7 @@ INSTANTIATE_TEST_SUITE_P(
             {
                 /*opcode=*/HloOpcode::kAllReduce,
                 /*comm=*/
-                GPUCommunicationType::NON_RAIL_ALIGNED,
+                GPUCommunicationType::MULTI_HOST_NON_WORLD_LEVEL,
                 /*tensor_size=*/1024,
                 /*num_nodes=*/3,
             },
@@ -567,7 +567,7 @@ INSTANTIATE_TEST_SUITE_P(
             {
                 /*opcode=*/HloOpcode::kAllReduce,
                 /*comm=*/
-                GPUCommunicationType::NON_RAIL_ALIGNED,
+                GPUCommunicationType::MULTI_HOST_NON_WORLD_LEVEL,
                 /*tensor_size=*/1024 + 256,
                 /*num_nodes=*/2,
             },
@@ -639,7 +639,7 @@ INSTANTIATE_TEST_SUITE_P(
             {
                 /*opcode=*/HloOpcode::kReduceScatter,
                 /*comm=*/
-                GPUCommunicationType::RAIL_ALIGNED,
+                GPUCommunicationType::MULTI_HOST_WORLD_LEVEL,
                 /*tensor_size=*/1024,
                 /*num_nodes=*/2,
             },
@@ -651,7 +651,7 @@ INSTANTIATE_TEST_SUITE_P(
             {
                 /*opcode=*/HloOpcode::kReduceScatter,
                 /*comm=*/
-                GPUCommunicationType::RAIL_ALIGNED,
+                GPUCommunicationType::MULTI_HOST_WORLD_LEVEL,
                 /*tensor_size=*/1024,
                 /*num_nodes=*/8,
             },
@@ -663,7 +663,7 @@ INSTANTIATE_TEST_SUITE_P(
             {
                 /*opcode=*/HloOpcode::kReduceScatter,
                 /*comm=*/
-                GPUCommunicationType::RAIL_ALIGNED,
+                GPUCommunicationType::MULTI_HOST_WORLD_LEVEL,
                 /*tensor_size=*/4 * 1024,
                 /*num_nodes=*/2,
             },
@@ -675,7 +675,7 @@ INSTANTIATE_TEST_SUITE_P(
             {
                 /*opcode=*/HloOpcode::kReduceScatter,
                 /*comm=*/
-                GPUCommunicationType::RAIL_ALIGNED,
+                GPUCommunicationType::MULTI_HOST_WORLD_LEVEL,
                 /*tensor_size=*/1024,
                 /*num_nodes=*/3,
             },
@@ -687,7 +687,7 @@ INSTANTIATE_TEST_SUITE_P(
             {
                 /*opcode=*/HloOpcode::kReduceScatter,
                 /*comm=*/
-                GPUCommunicationType::RAIL_ALIGNED,
+                GPUCommunicationType::MULTI_HOST_WORLD_LEVEL,
                 /*tensor_size=*/1024 + 256,
                 /*num_nodes=*/2,
             },
@@ -699,7 +699,7 @@ INSTANTIATE_TEST_SUITE_P(
             {
                 /*opcode=*/HloOpcode::kReduceScatter,
                 /*comm=*/
-                GPUCommunicationType::NON_RAIL_ALIGNED,
+                GPUCommunicationType::MULTI_HOST_NON_WORLD_LEVEL,
                 /*tensor_size=*/1024,
                 /*num_nodes=*/2,
             },
@@ -711,7 +711,7 @@ INSTANTIATE_TEST_SUITE_P(
             {
                 /*opcode=*/HloOpcode::kReduceScatter,
                 /*comm=*/
-                GPUCommunicationType::NON_RAIL_ALIGNED,
+                GPUCommunicationType::MULTI_HOST_NON_WORLD_LEVEL,
                 /*tensor_size=*/1024,
                 /*num_nodes=*/8,
             },
@@ -723,7 +723,7 @@ INSTANTIATE_TEST_SUITE_P(
             {
                 /*opcode=*/HloOpcode::kReduceScatter,
                 /*comm=*/
-                GPUCommunicationType::NON_RAIL_ALIGNED,
+                GPUCommunicationType::MULTI_HOST_NON_WORLD_LEVEL,
                 /*tensor_size=*/4 * 1024,
                 /*num_nodes=*/2,
             },
@@ -735,7 +735,7 @@ INSTANTIATE_TEST_SUITE_P(
             {
                 /*opcode=*/HloOpcode::kReduceScatter,
                 /*comm=*/
-                GPUCommunicationType::NON_RAIL_ALIGNED,
+                GPUCommunicationType::MULTI_HOST_NON_WORLD_LEVEL,
                 /*tensor_size=*/1032,
                 /*num_nodes=*/3,
             },
@@ -747,7 +747,7 @@ INSTANTIATE_TEST_SUITE_P(
             {
                 /*opcode=*/HloOpcode::kReduceScatter,
                 /*comm=*/
-                GPUCommunicationType::NON_RAIL_ALIGNED,
+                GPUCommunicationType::MULTI_HOST_NON_WORLD_LEVEL,
                 /*tensor_size=*/1024 + 256,
                 /*num_nodes=*/2,
             },
@@ -807,7 +807,7 @@ INSTANTIATE_TEST_SUITE_P(
             {
                 /*opcode=*/HloOpcode::kAllGather,
                 /*comm=*/
-                GPUCommunicationType::RAIL_ALIGNED,
+                GPUCommunicationType::MULTI_HOST_WORLD_LEVEL,
                 /*tensor_size=*/1024,
                 /*num_nodes=*/2,
             },
@@ -819,7 +819,7 @@ INSTANTIATE_TEST_SUITE_P(
             {
                 /*opcode=*/HloOpcode::kAllGather,
                 /*comm=*/
-                GPUCommunicationType::RAIL_ALIGNED,
+                GPUCommunicationType::MULTI_HOST_WORLD_LEVEL,
                 /*tensor_size=*/1024,
                 /*num_nodes=*/8,
             },
@@ -831,7 +831,7 @@ INSTANTIATE_TEST_SUITE_P(
             {
                 /*opcode=*/HloOpcode::kAllGather,
                 /*comm=*/
-                GPUCommunicationType::RAIL_ALIGNED,
+                GPUCommunicationType::MULTI_HOST_WORLD_LEVEL,
                 /*tensor_size=*/4 * 1024,
                 /*num_nodes=*/2,
             },
@@ -843,7 +843,7 @@ INSTANTIATE_TEST_SUITE_P(
             {
                 /*opcode=*/HloOpcode::kAllGather,
                 /*comm=*/
-                GPUCommunicationType::RAIL_ALIGNED,
+                GPUCommunicationType::MULTI_HOST_WORLD_LEVEL,
                 /*tensor_size=*/1056,
                 /*num_nodes=*/3,
             },
@@ -855,7 +855,7 @@ INSTANTIATE_TEST_SUITE_P(
             {
                 /*opcode=*/HloOpcode::kAllGather,
                 /*comm=*/
-                GPUCommunicationType::RAIL_ALIGNED,
+                GPUCommunicationType::MULTI_HOST_WORLD_LEVEL,
                 /*tensor_size=*/1024 + 256,
                 /*num_nodes=*/2,
             },
@@ -867,7 +867,7 @@ INSTANTIATE_TEST_SUITE_P(
             {
                 /*opcode=*/HloOpcode::kAllGather,
                 /*comm=*/
-                GPUCommunicationType::NON_RAIL_ALIGNED,
+                GPUCommunicationType::MULTI_HOST_NON_WORLD_LEVEL,
                 /*tensor_size=*/1024,
                 /*num_nodes=*/2,
             },
@@ -879,7 +879,7 @@ INSTANTIATE_TEST_SUITE_P(
             {
                 /*opcode=*/HloOpcode::kAllGather,
                 /*comm=*/
-                GPUCommunicationType::NON_RAIL_ALIGNED,
+                GPUCommunicationType::MULTI_HOST_NON_WORLD_LEVEL,
                 /*tensor_size=*/1024,
                 /*num_nodes=*/8,
             },
@@ -891,7 +891,7 @@ INSTANTIATE_TEST_SUITE_P(
             {
                 /*opcode=*/HloOpcode::kAllGather,
                 /*comm=*/
-                GPUCommunicationType::NON_RAIL_ALIGNED,
+                GPUCommunicationType::MULTI_HOST_NON_WORLD_LEVEL,
                 /*tensor_size=*/4 * 1024,
                 /*num_nodes=*/2,
             },
@@ -903,7 +903,7 @@ INSTANTIATE_TEST_SUITE_P(
             {
                 /*opcode=*/HloOpcode::kAllGather,
                 /*comm=*/
-                GPUCommunicationType::NON_RAIL_ALIGNED,
+                GPUCommunicationType::MULTI_HOST_NON_WORLD_LEVEL,
                 /*tensor_size=*/1032,
                 /*num_nodes=*/3,
             },
@@ -915,7 +915,7 @@ INSTANTIATE_TEST_SUITE_P(
             {
                 /*opcode=*/HloOpcode::kAllGather,
                 /*comm=*/
-                GPUCommunicationType::NON_RAIL_ALIGNED,
+                GPUCommunicationType::MULTI_HOST_NON_WORLD_LEVEL,
                 /*tensor_size=*/1024 + 256,
                 /*num_nodes=*/2,
             },
@@ -986,7 +986,7 @@ INSTANTIATE_TEST_SUITE_P(
             {
                 /*opcode=*/HloOpcode::kAllToAll,
                 /*comm=*/
-                GPUCommunicationType::RAIL_ALIGNED,
+                GPUCommunicationType::MULTI_HOST_WORLD_LEVEL,
                 /*tensor_size=*/1024,
                 /*num_nodes=*/2,
             },
@@ -997,7 +997,7 @@ INSTANTIATE_TEST_SUITE_P(
             {
                 /*opcode=*/HloOpcode::kAllToAll,
                 /*comm=*/
-                GPUCommunicationType::NON_RAIL_ALIGNED,
+                GPUCommunicationType::MULTI_HOST_NON_WORLD_LEVEL,
                 /*tensor_size=*/1024,
                 /*num_nodes=*/2,
             },
diff --git a/third_party/xla/xla/service/gpu/model/sol_latency_estimator.cc b/third_party/xla/xla/service/gpu/model/sol_latency_estimator.cc
index b6c91f08816..ad9a657549c 100644
--- a/third_party/xla/xla/service/gpu/model/sol_latency_estimator.cc
+++ b/third_party/xla/xla/service/gpu/model/sol_latency_estimator.cc
@@ -204,13 +204,13 @@ absl::StatusOr<absl::Duration> DispatchEstimation(
                       GetReplicaGroupCountAndSize(&instr));
 
   switch (comm) {
-    case GPUCommunicationType::RAIL_ALIGNED: {
+    case GPUCommunicationType::MULTI_HOST_WORLD_LEVEL: {
       return DCNCollectiveDuration(
           num_groups_and_devices->second / sol_flags.gpus_per_node,
           /*num_communicators=*/num_groups_and_devices->first, instr,
           gpu_device_info, sol_flags, analysis, symbolic_expr_context);
     }
-    case GPUCommunicationType::NON_RAIL_ALIGNED: {
+    case GPUCommunicationType::MULTI_HOST_NON_WORLD_LEVEL: {
       return DCNCollectiveDuration(
           num_groups_and_devices->second,
           /*num_communicators=*/num_groups_and_devices->first, instr,
diff --git a/third_party/xla/xla/service/gpu/transforms/collectives/collective_ops_utils.cc b/third_party/xla/xla/service/gpu/transforms/collectives/collective_ops_utils.cc
index 309498780a4..cd4b5e1ef57 100644
--- a/third_party/xla/xla/service/gpu/transforms/collectives/collective_ops_utils.cc
+++ b/third_party/xla/xla/service/gpu/transforms/collectives/collective_ops_utils.cc
@@ -115,7 +115,7 @@ bool IsSingleHost(const CommunicationMetadata& pattern) {
          pattern.replica_count <= pattern.num_devices_per_host;
 }
 
-bool IsRailAligned(const CommunicationMetadata& pattern) {
+bool IsWorldLevelCommunication(const CommunicationMetadata& pattern) {
   if (!IsSingleHost(pattern) && pattern.node_to_participant_count.empty()) {
     return true;
   }
@@ -126,8 +126,8 @@ bool IsRailAligned(const CommunicationMetadata& pattern) {
       });
 }
 
-bool IsNonRailAligned(const CommunicationMetadata& pattern) {
-  return !IsSingleHost(pattern) && !IsRailAligned(pattern);
+bool IsNonWorldLevelCommunication(const CommunicationMetadata& pattern) {
+  return !IsSingleHost(pattern) && !IsWorldLevelCommunication(pattern);
 }
 
 }  // namespace
@@ -152,11 +152,11 @@ absl::StatusOr<GPUCommunicationType> CommunicationType(
   if (IsSingleHost(comm)) {
     return GPUCommunicationType::SINGLE_HOST;
   }
-  if (IsRailAligned(comm)) {
-    return GPUCommunicationType::RAIL_ALIGNED;
+  if (IsWorldLevelCommunication(comm)) {
+    return GPUCommunicationType::MULTI_HOST_WORLD_LEVEL;
   }
-  if (IsNonRailAligned(comm)) {
-    return GPUCommunicationType::NON_RAIL_ALIGNED;
+  if (IsNonWorldLevelCommunication(comm)) {
+    return GPUCommunicationType::MULTI_HOST_NON_WORLD_LEVEL;
   }
 
   return GPUCommunicationType::UNDEFINED;
diff --git a/third_party/xla/xla/service/gpu/transforms/collectives/collective_ops_utils.h b/third_party/xla/xla/service/gpu/transforms/collectives/collective_ops_utils.h
index 62161101f5d..719940c9e4a 100644
--- a/third_party/xla/xla/service/gpu/transforms/collectives/collective_ops_utils.h
+++ b/third_party/xla/xla/service/gpu/transforms/collectives/collective_ops_utils.h
@@ -29,10 +29,10 @@ enum class GPUCommunicationType {
   UNDEFINED = 0,
   // Communication involves devices from multiple hosts, and every host
   // involved in the communication pattern has all of its devices participating.
-  RAIL_ALIGNED = 1,
+  MULTI_HOST_WORLD_LEVEL = 1,
   // Communication involves devices from multiple hosts, but at least one of
   // the involved hosts has only a subset of its devices participating.
-  NON_RAIL_ALIGNED = 2,
+  MULTI_HOST_NON_WORLD_LEVEL = 2,
   // All devices participating in the collective operation reside on the same
   // host machine.
   SINGLE_HOST = 3
diff --git a/third_party/xla/xla/service/gpu/transforms/collectives/collective_ops_utils_test.cc b/third_party/xla/xla/service/gpu/transforms/collectives/collective_ops_utils_test.cc
index 7ec6d51709d..35b9f1f5fc6 100644
--- a/third_party/xla/xla/service/gpu/transforms/collectives/collective_ops_utils_test.cc
+++ b/third_party/xla/xla/service/gpu/transforms/collectives/collective_ops_utils_test.cc
@@ -111,7 +111,7 @@ TEST_F(CommunicationTypeTest, DetectsSingleHost16Devices) {
               IsOkAndHolds(GPUCommunicationType::SINGLE_HOST));
 }
 
-TEST_F(CommunicationTypeTest, DetectRailAlignedAllDevices) {
+TEST_F(CommunicationTypeTest, DetectWorldLevelAllDevices) {
   absl::string_view kHlo = R"(
     HloModule m, num_partitions=16
 
@@ -131,10 +131,10 @@ TEST_F(CommunicationTypeTest, DetectRailAlignedAllDevices) {
       module->entry_computation()->root_instruction());
   EXPECT_THAT(CommunicationType(/*num_devices_per_host=*/8, *instr,
                                 device_info().gpu_compute_capability()),
-              IsOkAndHolds(GPUCommunicationType::RAIL_ALIGNED));
+              IsOkAndHolds(GPUCommunicationType::MULTI_HOST_WORLD_LEVEL));
 }
 
-TEST_F(CommunicationTypeTest, DetectRailAlignedHalfMesh) {
+TEST_F(CommunicationTypeTest, DetectWorldLevelHalfMesh) {
   absl::string_view kHlo = R"(
     HloModule m, num_partitions=32
 
@@ -157,10 +157,10 @@ TEST_F(CommunicationTypeTest, DetectRailAlignedHalfMesh) {
       module->entry_computation()->root_instruction());
   EXPECT_THAT(CommunicationType(/*num_devices_per_host=*/8, *instr,
                                 device_info().gpu_compute_capability()),
-              IsOkAndHolds(GPUCommunicationType::RAIL_ALIGNED));
+              IsOkAndHolds(GPUCommunicationType::MULTI_HOST_WORLD_LEVEL));
 }
 
-TEST_F(CommunicationTypeTest, DetectNonRailAligned) {
+TEST_F(CommunicationTypeTest, DetectNonWorldLevel) {
   absl::string_view kHlo = R"(
     HloModule m, num_partitions=16
 
@@ -180,7 +180,7 @@ TEST_F(CommunicationTypeTest, DetectNonRailAligned) {
       module->entry_computation()->root_instruction());
   EXPECT_THAT(CommunicationType(/*num_devices_per_host=*/8, *instr,
                                 device_info().gpu_compute_capability()),
-              IsOkAndHolds(GPUCommunicationType::NON_RAIL_ALIGNED));
+              IsOkAndHolds(GPUCommunicationType::MULTI_HOST_NON_WORLD_LEVEL));
 }
 
 TEST_F(CommunicationTypeTest, DetectsSingleHost16DevicesForEmptyReplicaGroups) {
@@ -204,7 +204,7 @@ TEST_F(CommunicationTypeTest, DetectsSingleHost16DevicesForEmptyReplicaGroups) {
               IsOkAndHolds(GPUCommunicationType::SINGLE_HOST));
 }
 
-TEST_F(CommunicationTypeTest, DetectsRailAligned8DevicesForEmptyReplicaGroups) {
+TEST_F(CommunicationTypeTest, DetectWorldLevel8DevicesForEmptyReplicaGroups) {
   absl::string_view kHlo = R"(
     HloModule m, replica_count=16
 
@@ -222,10 +222,10 @@ TEST_F(CommunicationTypeTest, DetectsRailAligned8DevicesForEmptyReplicaGroups) {
       module->entry_computation()->root_instruction());
   EXPECT_THAT(CommunicationType(/*num_devices_per_host=*/8, *instr,
                                 device_info().gpu_compute_capability()),
-              IsOkAndHolds(GPUCommunicationType::RAIL_ALIGNED));
+              IsOkAndHolds(GPUCommunicationType::MULTI_HOST_WORLD_LEVEL));
 }
 
-TEST_F(CommunicationTypeTest, DetectsNonRailAligned16Devices) {
+TEST_F(CommunicationTypeTest, DetectNonWorldLevel16Devices) {
   absl::string_view kHlo = R"(
     HloModule m, replica_count=16
 
@@ -243,7 +243,7 @@ TEST_F(CommunicationTypeTest, DetectsNonRailAligned16Devices) {
       module->entry_computation()->root_instruction());
   EXPECT_THAT(CommunicationType(/*num_devices_per_host=*/8, *instr,
                                 device_info().gpu_compute_capability()),
-              IsOkAndHolds(GPUCommunicationType::NON_RAIL_ALIGNED));
+              IsOkAndHolds(GPUCommunicationType::MULTI_HOST_NON_WORLD_LEVEL));
 }
 
 TEST_F(CommunicationTypeTest, DetectsSingleHostCollectivePermute) {
@@ -266,7 +266,7 @@ TEST_F(CommunicationTypeTest, DetectsSingleHostCollectivePermute) {
               IsOkAndHolds(GPUCommunicationType::SINGLE_HOST));
 }
 
-TEST_F(CommunicationTypeTest, DetectsNonRailAlignedCollectivePermute) {
+TEST_F(CommunicationTypeTest, DetectNonWorldLevelCollectivePermute) {
   absl::string_view kHlo = R"(
     HloModule m, num_partitions=16
 
@@ -284,10 +284,10 @@ TEST_F(CommunicationTypeTest, DetectsNonRailAlignedCollectivePermute) {
       module->entry_computation()->root_instruction());
   EXPECT_THAT(CommunicationType(/*num_devices_per_host=*/8, *instr,
                                 device_info().gpu_compute_capability()),
-              IsOkAndHolds(GPUCommunicationType::NON_RAIL_ALIGNED));
+              IsOkAndHolds(GPUCommunicationType::MULTI_HOST_NON_WORLD_LEVEL));
 }
 
-TEST_F(CommunicationTypeTest, DetectsRailAlignedCollectivePermute) {
+TEST_F(CommunicationTypeTest, DetectWorldLevelCollectivePermute) {
   absl::string_view kHlo = R"(
     HloModule m, num_partitions=16
 
@@ -304,7 +304,7 @@ TEST_F(CommunicationTypeTest, DetectsRailAlignedCollectivePermute) {
       module->entry_computation()->root_instruction());
   EXPECT_THAT(CommunicationType(/*num_devices_per_host=*/8, *instr,
                                 device_info().gpu_compute_capability()),
-              IsOkAndHolds(GPUCommunicationType::RAIL_ALIGNED));
+              IsOkAndHolds(GPUCommunicationType::MULTI_HOST_WORLD_LEVEL));
 }
 
 }  // namespace