cgi.FieldStorage() not work for python requests.post but work for requests.get

Fri May 5 06:01:44 EDT 2017

here is the client use get 
------------------------------------------------------------------
import json 
import requests 

url = "http://abc.com:11/ip" 
auth = {"ip":["10.100.1.1","10.100.1.2"], 
         "time": "20170504133025" 
        } 

try: 
    req = requests.get(url,params=auth)     

except requests.exceptions.ConnectionError,e: 
    print e 
else: 
    print req 
    print req.headers 
    print req.text 
------------------------------------------------------------------

but not work for post 
------------------------------------------------------------------
import json 
import requests 

url = "http://abc.com:11/ip" 
auth = {"ip":["10.100.1.1","10.100.1.2"], 
         "time": "20170504133025" 
        } 

try: 
    headers = {'Content-Type': 'application/json'} 
    req = requests.post(url=url,data=json.dumps(auth),headers=headers) 

except requests.exceptions.ConnectionError,e: 
    print e 
else: 
    print req 
    print req.headers 
    print req.text 
------------------------------------------------------------------
arguments always get FieldStorage(None, None, []) 

and i use other post way, it works. 
------------------------------------------------------------------
<!DOCTYPE html> 
<html><head><title>login</title></head> 
<body> 
<form action="http://abc.com:11/ip/" method="post"> 
<input type="text" name="ip"/> 
<input type="text" name="time"/> 
<input type="submit"/> 
</form> 
</body> 
</html> 
------------------------------------------------------------------

is this any problem requests.post(python) with cgi.FieldStorage ? 

Thanks 