mininet.net.Mininet

模拟一个 Mininet 中的网络，包括拓扑、交换机、主机、控制器、链路、接口等。 其中最主要的部分是 build() 函数，依次执行：根据拓扑创建网络，配置网络名字空间，配置主机的 IP、MAC 等信息，检查是否启动 xterm，是否配置自动静态 arp 等。

init

          inNamespace=False,
                  autoSetMacs=False, autoStaticArp=False, autoPinCpus=False,
                  listenPort=None ):
        """Create Mininet object.
           topo: Topo (topology) object or None
           switch: default Switch class
           host: default Host class/constructor
           controller: default Controller class/constructor
           link: default Link class/constructor
           intf: default Intf class/constructor
           ipBase: base IP address for hosts,
           build: build now from topo?
           xterms: if build now, spawn xterms?
           cleanup: if build now, cleanup before creating?
           inNamespace: spawn switches and controller in net namespaces?
           autoSetMacs: set MAC addrs automatically like IP addresses?
           autoStaticArp: set all-pairs static MAC addrs?
           autoPinCpus: pin hosts to (real) cores (requires CPULimitedHost)?
           listenPort: base listening port to open; will be incremented for
               each additional switch in the net if inNamespace=False"""
        self.topo = topo
        self.switch = switch
        self.host = host
        self.controller = controller
        self.link = link
        self.intf = intf
        self.ipBase = ipBase
        self.ipBaseNum, self.prefixLen = netParse( self.ipBase )
        self.nextIP = 1  # start for address allocation
        self.inNamespace = inNamespace
        self.xterms = xterms
        self.cleanup = cleanup
        self.autoSetMacs = autoSetMacs
        self.autoStaticArp = autoStaticArp
        self.autoPinCpus = autoPinCpus
        self.numCores = numCores()
        self.nextCore = 0  # next core for pinning hosts to CPUs
        self.listenPort = listenPort

        self.hosts = []
        self.switches = []
        self.controllers = []

        self.nameToNode = {}  # name to Node (Host/Switch) objects

        self.terms = []  # list of spawned xterm processes

        Mininet.init()  # Initialize Mininet if necessary

        self.built = False
        if topo and build:
            self.build()

该方法主要根据传入参数配置相关的数据结构。如果还通过参数执行了拓扑信息，则执行 build 方法，调用 buildFromTopo 方法来根据拓扑信息创建节点和相关的连接等。

buildFromTopo

def buildFromTopo( self, topo=None ):
        """Build mininet from a topology object
           At the end of this function, everything should be connected
           and up."""

        # Possibly we should clean up here and/or validate
        # the topo
        if self.cleanup:
            pass

        info( '*** Creating network\n' )

        if not self.controllers and self.controller:
            # Add a default controller
            info( '*** Adding controller\n' )
            classes = self.controller
            if type( classes ) is not list:
                classes = [ classes ]
            for i, cls in enumerate( classes ):
                self.addController( 'c%d' % i, cls )

        info( '*** Adding hosts:\n' )
        for hostName in topo.hosts():
            self.addHost( hostName, **topo.nodeInfo( hostName ) )
            info( hostName + ' ' )

        info( '\n*** Adding switches:\n' )
        for switchName in topo.switches():
            self.addSwitch( switchName, **topo.nodeInfo( switchName) )
            info( switchName + ' ' )

        info( '\n*** Adding links:\n' )
        for srcName, dstName in topo.links(sort=True):
            src, dst = self.nameToNode[ srcName ], self.nameToNode[ dstName ]
            params = topo.linkInfo( srcName, dstName )
            srcPort, dstPort = topo.port( srcName, dstName )
            self.addLink( src, dst, srcPort, dstPort, **params )
            info( '(%s, %s) ' % ( src.name, dst.name ) )

        info( '\n' )