Cisco's SDLC local acknowledgment provides local termination of the SDLC session so that control frames no longer travel the WAN backbone networks. This means end nodes do not time out, and a loss of sessions does not occur. You can configure your network with STUN, or with STUN and SDLC local acknowledgment. To enable SDLC local acknowledgment, the Cisco IOS software must first be enabled for STUN and routers configured to appear on the network as primary or secondary SDLC nodes. TCP/IP encapsulation must be enabled. Cisco's SDLC Transport feature also provides priority queuing for TCP encapsulated frames.
This was first published in June 2003