Support out-of-order link addition

Sort interface names before passing to dpctl for kernel switch, so that
links for multipath topologies can be added in any order.

mininet/net.py

@@ -159,6 +159,8 @@ def _add_link(self, src, dst):
  make_veth_pair(src_intf, dst_intf)
  src_node.intfs.append(src_intf)
  dst_node.intfs.append(dst_intf)
+ src_node.ports[src_port] = src_intf
+ dst_node.ports[dst_port] = dst_intf
  #lg.info('\n')
  #lg.info('added intf %s to src node %x\n' % (src_intf, src))
  #lg.info('added intf %s to dst node %x\n' % (dst_intf, dst))

mininet/node.py

@@ -41,6 +41,8 @@ def __init__(self, name, inNamespace = True):
  self.connection = {}
  self.waiting = False
  self.execed = False
+ self.ports = {} # dict of ints to interface strings
+ # replace with Port object, eventually
 
  def fdToNode(self, f):
  '''Insert docstring.
@@ -316,8 +318,12 @@ def start(self, controllers):
  intf = 'of%i' % self.dp
  mac_str = macColonHex(self.dpid)
  self.cmd(['ifconfig', intf, 'hw', 'ether', mac_str])
- self.cmdPrint('dpctl addif nl:' + str(self.dp) + ' ' +
- ' '.join(self.intfs))
+
+ if len(self.ports) != max(self.ports.keys()) + 1:
+ raise Exception('only contiguous, zero-indexed port ranges'
+ 'supported: %s' % self.ports)
+ intfs = [self.ports[port] for port in self.ports.keys()]
+ self.cmdPrint('dpctl addif nl:' + str(self.dp) + ' ' + ' '.join(intfs))
  # Run protocol daemon
  self.cmdPrint('ofprotocol nl:' + str(self.dp) + ' tcp:' +
  controllers['c0'].IP() + ':' +