In this assignment, your task is to create a simple tree topology. You will assume each level i.e., core, aggregation, edge and host to be composed of a single layer of switches/hosts with a configurable fanout value (k) looks like:
代码：
# CustomTopo.py
'''
Coursera:
- Software Defined Networking (SDN) course
-- Module 3 Programming Assignment
Professor: Nick Feamster
Teaching Assistant: Muhammad Shahbaz
'''
from mininet.topo import Topo
from mininet.net import Mininet
from mininet.node import CPULimitedHost
from mininet.link import TCLink
from mininet.util import irange,dumpNodeConnections
from mininet.log import setLogLevel
class CustomTopo(Topo):
"Simple Data Center Topology"
"linkopts - (1:c1, 2:aggregation, 3: edge) parameters"
"fanout - number of child switch per parent switch"
def __init__(self, linkopts1, linkopts2, linkopts3, fanout=2, **opts):
# Initialize topology and default options
Topo.__init__(self, **opts)
# Add your logic here ...
self.fanout = fanout
core = self.addSwitch('c1')
for i in irange(1, fanout):
aggregation = self.addSwitch('a%s' %i)
self.addLink(core, aggregation, **linkopts1)
for j in irange(1, fanout):
edge = self.addSwitch('e%s' %(fanout*(i-1)+j))
self.addLink(aggregation, edge, **linkopts2)
for k in irange(1, fanout):
host = self.addHost('h%s' %((fanout*(fanout*(i-1)+j-1))+k))
self.addLink(edge, host, **linkopts3)
topos = { 'custom': ( lambda: CustomTopo() ) }
def simpleTest():
"Create and test a simple network"
linkopts1 = dict(bw=10, delay='3ms', use_htb=True)
linkopts2 = dict(bw=8, delay='4ms', loss=1, max_queue_size=900, )
linkopts3 = dict(bw=6, delay='5ms', loss=1, max_queue_size=800)
topo = CustomTopo(linkopts1, linkopts2, linkopts3, fanout=2)
net = Mininet(topo, host=CPULimitedHost, link=TCLink)
net.start()
print "Dumping host connections"
dumpNodeConnections(net.hosts)
print "Testing network connectivity"
net.pingAll()
net.stop()
if __name__ == '__main__':
# Tell mininet to print useful information
setLogLevel('info')
simpleTest()
在mininet虚拟机上执行下面操作即可创建自定义的网络拓扑。函数simpleTest()创建网络并进行了简单的ping测试，从屏幕输出可以看到创建的过程。
mininet@mininet-vm:~/mininet$ sudo python CustomTopo.py
