With EE, you can adhere to SNA transmission priorities across IP networks, sending batch transfers and smaller interactive sessions efficiently. EE maps SNA transmission priorities to the IP type of service (ToS) header. To take advantage of the mapping, you must correctly configure IP routers and switches to accommodate the IP ToS settings. If the configuration is incorrect, SNA priorities are not applied to data as it travels across the IP network.

Distinct routing algorithms can differentiate among IP packet priorities, and these algorithms have to be established as you set up routing hardware. You need to set up routers to process the ToS value that you want. SNA transmission priorities are competing against native IP applications and every other application using the WAN; for example, FTP, Telnet, and web-based traffic. EE is just another application competing for priority.

Establish traffic prioritization (ToS settings) as you design your EE network. Consult the appropriate documentation specific to your router to establish the correct traffic prioritization. Host personnel and network engineers need to agree on ToS values so that applications get the priority they need. If this is not done before implementation, EE will not be effective and SNA traffic will not get the proper priority on the router. Figure 1 shows how ToS settings affect IP traffic.

Figure 1. How ToS settings affect IP traffic

See z/OS Communications Server: IP Configuration Guide for more information about ToS.