RYU环境搭建总共四步：
step1：首先下载相应的python套件，并且更新pip
$ sudo apt-get install python-pip python-dev build-essential
$ sudo pip install --upgrade pip
step2:安装RYU相关套件
$ sudo apt-get install python-eventlet
$ sudo apt-get install python-routes
$ sudo apt-get install python-paramiko
$ sudo apt-get install python-webob
step3:安装RYU，有两种方案，推荐第一种，
<1>使用pip安装RYU $ sudo pip install ryu
<2>使用git下载ryu源码安装
$ git clone git://github.com/osrg/ryu.git
$ cd ryu
$ sudo python setup.py install
step4:安装RYU基本完成,运行ryu-manager出现如下两种情况，<1>说明安装成功
<1>出现： loading app ryu.controller.ofp_handler
instantiating app ryu.controller.ofp_handler of OFPHandler
<2>Traceback (most recent call last):
……
dists = vs.resolve(reqs,Enviroment())
File "/usr/lib/python2.7/dist-packages/pkg_resources.py", line 632 in resolve
raise VersionConflict(dist,req) # XXX put more info here
pkg_resources.VersionConflict:(six 1.5.2 (/usr/lib/python2.7/dist-packages), Requirement.parse('six>=1.9.0'))
这一问题说明pip版本不匹配，解决方案如下：
$ sudo apt-get remove python-pip
$ wget https://raw.github.com/pypa/pip/master/contrib/get-pip.py
$ pip install --upgrade six