Bracket and half-duplex protocol

IMS uses SNA bracket protocol to resolve contention, and uses the change-direction indicator of the half-duplex protocol to control normal flow send/receive mode while within bracket state.

IMS uses these options when in session with another ISC logical unit:
  • Bracket reset state can be selected at data traffic active state. This state can be set to between-brackets (BETB) or in-brackets (INB).
  • Half-duplex send or receive state can be selected at data traffic active state.
  • Either half session can send end-bracket (EB). IMS must always be bound to allow EB.
  • Half-duplex flip-flop is used for normal flow send/receive states.
  • Bracket termination rule 1 (conditional rule) is used.
Related reading:
  • For information on bracket termination rules, see z/OS® Communications Server: SNA Programming.