content_image/983494.jpg
Figure 3-15 shows the suggested designations for 2145-SV1 nodes. 

<img src='content_image/983494.jpg'>

Important:  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 shown in the tables 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 a 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. Using local FC port masking, you can set which ports can be used for node-to-node/intracluster communication. 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 a 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 because it saves setting up many SAN zones. 

