Request Transport#

LMCache MP clients select the request transport from the LMCache server URL. This transport carries control and cache-operation requests; it is separate from --supported-transfer-mode, which controls how KV data moves between the engine worker and the LMCache server.

Transport schemes#

Endpoint	Transport	Status
`host:port` or `tcp://host:port`	ZMQ over TCP	Supported. A URL without a scheme defaults to `tcp://`.
`ipc://path` or `inproc://name`	ZMQ IPC or in-process	Recognized by the client factory; the standard LMCache server currently binds ZMQ over TCP.
`grpc://host:port` or `grpc+unix:///path`	gRPC	Not supported yet. gRPC support is planned soon.

For a single vLLM connector, set the scheme in lmcache.mp.host and keep the port in lmcache.mp.port. The current ZMQ configuration is:

{
  "lmcache.mp.host": "tcp://localhost",
  "lmcache.mp.port": 5555
}

When gRPC becomes available, selecting it will use the same configuration shape with a grpc:// host:

{
  "lmcache.mp.host": "grpc://localhost",
  "lmcache.mp.port": 5555
}

For multiple servers, specify the scheme on every entry in lmcache.mp.server_urls, for example tcp://host1:5555,tcp://host2:5555. All clients and servers in a deployment must use matching transports.