'Enter into configuration mode on remote device.
Cisco IOS devices abbreviate the prompt at 20 chars in config mode'

def config_mode(self, config_command=u'config    term', pattern=u''):

    if (not pattern):
        pattern = re.escape(self.base_prompt[:16])
    return super(CiscoBaseConnection, self).config_mode(config_command=config_command, pattern=pattern)
