IBM Optimizing Cisco STUN Priority 1 Port on Networking Routers

Overview of IBM Networking

STUN and BSTUN

Figure 89 Comparison of STUN in Passthrough Mode and Local Acknowledgment Mode

37x5	WAN
IBM 1

SDLC session

SNA session

TCP session

37x5	WAN
IBM 1

3x74

IBM1

3x74

IBM 2

SDLC session

SNA session

SDLC session

S2839

Note To enable STUN local acknowledgment, you first enable the routers for STUN and configure them to appear on the network as primary or secondary SDLC nodes. TCP/IP encapsulation must be enabled. The Cisco STUN local acknowledgment feature also provides priority queueing for TCP-encapsulated frames.

STUN Features

The Cisco STUN implementation provides the following features:

•Encapsulates SDLC frames in either the Transmission Control Protocol/Internet Protocol (TCP/IP) or the HDLC protocol.

•Allows two devices using SDLC- or HDLC-compliant protocols that are normally connected by a direct serial link to be connected through one or more Cisco routers, reducing leased-line costs.

When you replace direct serial links with routers, serial frames can be propagated over arbitrary media and topologies to another router with a STUN link to an appropriate endpoint. The intervening network is not restricted to STUN traffic, but rather, is multiprotocol. For example, instead of running parallel backbones for DECnet and SNA/SDLC traffic, this traffic now can be integrated into an enterprise backbone network.

•Supports local acknowledgment for direct Frame Relay connectivity between routers, without requiring TCP/IP.

	Cisco IOS Bridging and IBM Networking Configuration Guide
BC-212	78-11737-02