Note: The CCL product gives you a way to migrate devices from your NNP hardware to CCL NCP boundary function and reduces the risk of encountering problems with running out of SNA element addresses in a VTAM subarea. Though using CCL might increase the host CPU cycles overall, CCL CPU cycles may be less expensive than other mainframe CPU cycles because Linux partitions can use Integrated Facility for Linux (IFL) processors. See Chapter 16, "Communication Controller for Linux on System z9 and zSeries (CCL)" on page 283 for additional information about CCL. Recommendation Pursue strategic migrations first. Strategic migrations such as migrating from SNA 3270 to TN3270 or Web-enabling applications and deploying Web browsers can simultaneously work to position your organization to support new applications while also reducing your dependency on SNA. Through such migrations, you may be able to gradually reduce the SNA environment to the point that removing your NNP APPN support will have minimal impact. If however, you will be required to support a substantial and mission-critical SNA environment for the foreseeable future, then pursue one of the following two approaches: If the remaining SNA environment will be too large to be supported by a single VTAM or is very important (in terms of performance or availability), then