how can I set the value of PDO_LEDGER_URL corretly?

[zlonqi]

I'm running the sawtooth ledger service on one machine(116.56.129.17) flowwed by guide but I run PDO test on another machine(202...*), how can I set the value of PDO_LEDGER_URL corretly?
thank you so much.
I set PDO_LEDGER_URL=116.56.129.17:8008. and I'm sure rest-api listen on port 8008 on machine(116.56.129.17), How should I configure it？I really don't know how PDO on local connect to sawtooth ledger service on 116.56.129.17.
Any suggestion will be accepted. Thanks a lot.
And I got some message when I make test:

pdo.eservice.pdo_helper] failed to register enclave; Failed to connect to REST API: HTTPConnectionPool(host='116.56.129.17', port=8008): Max retries exceeded with url: /batches (Caused by NewConnectionError('<urllib3.connection.HTTPConnection object at 0x7eb2681b36a0>: Failed to establish a new connection: [Errno 111] Connection refused',))

[zlonqi]

I've solved it by port map