def _parse_class_args(self):
        """Parse the contrailplugin.ini file.

        Opencontrail supports extension such as ipam, policy, these extensions
        can be configured in the plugin configuration file as shown below.
        Plugin then loads the specified extensions.
        contrail_extensions=ipam:<classpath>,policy:<classpath>
        """

        contrail_extensions = cfg.CONF.APISERVER.contrail_extensions
        # If multiple class specified for same extension, last one will win
        # according to DictOpt behavior
        for ext_name, ext_class in contrail_extensions.items():
            try:
                if not ext_class:
                    LOG.error(_('Malformed contrail extension...'))
                    continue
                self.supported_extension_aliases.append(ext_name)
                ext_class = importutils.import_class(ext_class)
                ext_instance = ext_class()
                ext_instance.set_core(self)
                for method in dir(ext_instance):
                    for prefix in ['get', 'update', 'delete', 'create']:
                        if method.startswith('%s_' % prefix):
                            setattr(self, method,
                                    ext_instance.__getattribute__(method))
            except Exception:
                LOG.exception(_("Contrail Backend Error"))
                # Converting contrail backend error to Neutron Exception
                raise InvalidContrailExtensionError(
                    ext_name=ext_name, ext_class=ext_class)

        #keystone
        self._authn_token = None
        if cfg.CONF.auth_strategy == 'keystone':
            kcfg = cfg.CONF.keystone_authtoken
            body = '{"auth":{"passwordCredentials":{'
            body += ' "username": "%s",' % (kcfg.admin_user)
            body += ' "password": "%s"},' % (kcfg.admin_password)
            body += ' "tenantName":"%s"}}' % (kcfg.admin_tenant_name)

            self._authn_body = body
            self._authn_token = cfg.CONF.keystone_authtoken.admin_token
            self._keystone_url = "%s://%s:%s%s" % (
                cfg.CONF.keystone_authtoken.auth_protocol,
                cfg.CONF.keystone_authtoken.auth_host,
                cfg.CONF.keystone_authtoken.auth_port,
                "/v2.0/tokens")