IBM BC-203 - Manual (Page 12)

Overview of IBM Networking
STUN and BSTUN
BC-214
Cisco IOS Bridging and IBM Networking Configuration Guide
Figure 89 Comparison of STUN in Passthrough Mode and Local Acknowledgment Mode
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. Cisco’s STUN local acknowledgment feature also provides
priority queueing for TCP-encapsulated frames.
STUN Features
Cisco’s 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 end point. 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.
WAN
SDLC session
37x5
IBM 1
SNA session
3x74
IBM1
S2839
SDLC session
TCP session
SDLC session
37x5
IBM 1
3x74
IBM 2
SNA session
WAN