text: **Note:**With 12 or more ports per node, four ports should be dedicated for node-to-node 
  traffic. Doing so is especially important when high write data rates are expected because 
  all writes are mirrored between I/O Group nodes over these ports. 
  
  The port designation patterns that are shown in 3.6, “SAN configuration planning” on page 50 
  provide the required traffic isolation and simplify migrations to configurations with greater 
  number of ports. More complicated port mapping configurations that spread the port traffic 
  across the adapters are supported and can be considered. However, these approaches do 
  not appreciably increase availability of the solution. 
  
  Alternative port mappings that spread traffic across HBAs might allow adapters to come back 
  online following a failure. However, they do not prevent a node from going offline temporarily 
  to restart and attempt to isolate the failed adapter and then rejoin the cluster. Also, the mean 
  time between failures (MTBF) of the adapter is not significantly shorter than that of the 
  non-redundant node components. The presented approach takes all of these considerations 
  into account with a view that increased complexity can lead to migration challenges in the 
  future, and simpler approach is usually better. 
  
  **3.6.8 Port masking**
  
  You can use a port mask to control the node target ports that a host can access. By using 
  local FC port masking, you can set which ports can be used for node-to-node/intracluster 
  communication. By using remote FC port masking, you can set which ports can be used for 
  replication communication. Port masking, combined with zoning, enables you to dedicate 
  ports to particular type of traffic. Setting up Fibre Channel port masks is particularly useful 
  when you have more than four Fibre Channel ports on any node in the system, as it saves 
  setting up many SAN zones. 