Using predefined EE, how can we improve throughput and response time in constrained or virtualized environments?

You can use progressive mode ARB (adaptive-rate-based pacing) to enable HPR to perform reliably and consistently in platforms using virtualization. Progressive mode ARB is an HPR flow control mechanism that improves the performance of HPR in these environments. Progressive mode ARB is available only to single-hop HPR pipes that are over TCP/IP, which includes a single physical hop across a two-hop EE virtual routing node (VRN).

You use the HPREEARB parameter to specify that predefined EE connections will enable progressive mode ARB. Code HPREEARB=PROGRESS on the GROUP or PU definition statement in the switched major node to specify that the progressive-mode ARB flow control algorithm is used for the HPR pipes that traverse this predefined EE connection.

When defined, VTAM negotiates with the HPR partner whether progressive mode ARB will be used on the RTP connection. If both partners require to use progressive mode ARB and the HPR pipe is a single hop over EE (which includes a single physical hop across a two-hop EE VRN), then progressive mode ARB will be used.

A display of the RTP pipe will show that progressive mode ARB is being used

If not specified, the HPREEARB parameter defaults to HPRARB, which specifies that the HPRARB start option value is used to determine the ARB flow control algorithm for the HPR pipes that traverse this predefined EE connection. The default value for the HPRARB start option is RESPMODE. which specifies that responsive-mode ARB is to used as the flow control algorithm. This algorithm is most suitable to environments which are not constrained.