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Document ID: 5206
Contents
Introduction
Prerequisites
Requirements
Components Used
Conventions
SDLC States
SDLLC States
Related Information
Introduction
This document defines and explains various states of Synchronous Data Link Control (SDLC) and SDLC-to-LAN Conversion (SDLLC).
Prerequisites
Requirements
There are no specific requirements for this document.
Components Used
This document is not restricted to specific software or hardware versions.
Conventions
For more information on document conventions, refer to the Cisco Technical Tips Conventions.
SDLC States
DISCONNECT—Disconnected from physical units (PUs). No communication is being attempted to this secondary.
DISCSENT—This router has sent a disconnect request (DISC) to this secondary and is awaiting its response.
SNRMSENT—This router has sent a connect request (SNRM) to this secondary and is awaiting its response.
CONNECT—Connected with PU. A normal connect state exists between this router and this secondary.
THEMBUSY—PU sending receiver not ready (RNR). This secondary has told this router that it is temporarily unable to receive any more information frames.
USBUSY—This router is sending RNR to the SDLC-attached device. This router has told this secondary that it is temporarily unable to receive any more information frames. This means that this router is waiting for the other end (like the host device) to respond.
BOTHBUSY—Both stations are sending RNR. Both sides have told each other that they are temporarily unable to receive any more information frames.
ERROR—SDLC protocol violation. This router has detected an error and is waiting for a response from the secondary, acknowledging this detection.
SNRMSEEN—Router is secondary and received SNRM.
SDLLC States
This is the SDLC primary connection order:
DISCONNECT > SDLC PRI WAIT > NET UP WAIT > CONNECT
This is the SDLC secondary connection order:
DISCONNECT > NET UP WAIT > SDLC SEC WAIT > CONNECT
DISCONNECT—Disconnected from PU.
CONNECT—Fully connected, data flowing.
SDLC DISC WAIT—Waiting for SDLC to disconnect.
SDLC PRI WAIT—Waiting for primary SDLC to come up.
SDLC SEC WAIT—Waiting for secondary SDLC to come up.
NET UP WAIT—Waiting for net media, token ring, or network (Logical Link Control [LLC] side).
SDLC SEC WAIT—Waiting for secondary SDLC to come up.
NET DISC WAIT—Waiting for network side to get torn down.
Related Information
| Updated: Sep 09, 2005 | Document ID: 5206 |