tree 825e57a91e299102fce7c6801c2acd1ad0be9059
parent fd8c7d7288635bb91156e7429badb2dd0e9a1fc8
author Pingping Lin <pingping@onlab.us> 1428702161 -0700
committer Jonathan Hart <jono@onlab.us> 1429115474 +0000

add a virtual gateway for reactive routing

  There is no physical gateway in SDN network.
  However a host needs a gateway when it tries to communicate with a remote host.
  So we designed a virtual gateway for SDN network.
  The virtual gateway can have multiple IP addresses.
  Each IP address is used as the default gateway address of an IP prefix.
  We only configure one MAC address to the virtual gateway.
  You can choose any MAC address from the BGP speakers as the virtual gateway MAC address.
  We configure this MAC address staticly in the sdnip.json configuration file.

Change-Id: I2a72bef797fc55d25bb5473e8fca624ad659e1d1