[PD] Add NIXL transfer backend (#5477)

python/sglang/srt/disaggregation/nixl/__init__.py

+from .conn import NixlKVBootstrapServer, NixlKVManager, NixlKVReceiver, NixlKVSender

python/sglang/srt/disaggregation/utils.py

@@ -47,6 +47,7 @@ class ReqToMetadataIdxAllocator:
 
 class TransferBackend(Enum):
     MOONCAKE = "mooncake"
+    NIXL = "nixl"
     FAKE = "fake"
 
 
@@ -73,6 +74,21 @@ def get_kv_class(transfer_backend: TransferBackend, class_type: KVClassType):
             KVClassType.BOOTSTRAP_SERVER: MooncakeKVBootstrapServer,
         }
         return class_mapping.get(class_type)
+    if transfer_backend == TransferBackend.NIXL:
+        from sglang.srt.disaggregation.nixl import (
+            NixlKVBootstrapServer,
+            NixlKVManager,
+            NixlKVReceiver,
+            NixlKVSender,
+        )
+
+        class_mapping = {
+            KVClassType.MANAGER: NixlKVManager,
+            KVClassType.SENDER: NixlKVSender,
+            KVClassType.RECEIVER: NixlKVReceiver,
+            KVClassType.BOOTSTRAP_SERVER: NixlKVBootstrapServer,
+        }
+        return class_mapping.get(class_type)
     raise ValueError(f"Unsupported transfer backend: {transfer_backend}")
 
 

python/sglang/srt/server_args.py

@@ -1211,6 +1211,7 @@ class ServerArgs:
             "--disaggregation-transfer-backend",
             type=str,
             default=ServerArgs.disaggregation_transfer_backend,
+            choices=["mooncake", "nixl"],
             help="The backend for disaggregation transfer. Default is mooncake.",
         )
         parser.add_argument(