[P4-dev] bmv2: "Error when requesting config md5 sum from switch"

David Hancock dhancock at cs.utah.edu
Sat Sep 15 21:23:18 EDT 2018


Hello,

I get "Error when requesting config md5 sum from switch" when executing:

runtime_CLI.load_json_config(<bm_runtime.standard.Standard.Client 
object>, <JSON path>)

in my python-based controller that connects to a bmv2 simple_switch.  I 
did not get this error in mininet experiments; I'm only getting it now 
that I'm trying to experiment on a physical cluster.

Is there a common reason for that error?

Here is some of the code preceding the statement that results in the error:

     ip = 'localhost'
     port = 9090

     services = 
runtime_CLI.RuntimeAPI.get_thrift_services(runtime_CLI.PreType.SimplePre)
     services.extend(SimpleSwitchAPI.get_thrift_services())

     try:
       std_client, mc_client, sswitch_client = 
runtime_CLI.thrift_connect(ip, port, services)
     except:
         return "Error - create_device(" + dev_name + "): " + 
str(sys.exc_info()[0])

     json = <path to JSON>
     runtime_CLI.load_json_config(std_client, json)

I can break right before the load_json_config call and everything looks 
in order - in particular, get_thrift_services and thrift_connect 
executed successfully.

Thank you for any ideas you may have,

David




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