ACC HDLC/LAP-B (ABM) User’s Guide Edition 1 HP 9000 Networking Manufacturing Part Number : Z7345-90011 E0204 © Copyright 2004 Hewlett-Packard Company.
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This software is based in part on the Fourth Berkeley Software Distribution under license from the Regents of the University of California. © copyright 1980, 1984, 1986 Novell, Inc. © copyright 1986-1992 Sun Microsystems, Inc. © copyright 1985-86, 1988 Massachusetts Institute of Technology. © copyright 1989-93 The Open Software Foundation, Inc. © copyright 1986 Digital Equipment Corporation. © copyright 1990 Motorola, Inc.
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Preface The HDLC/LAP-B (ABM) Protocol product is used in conjunction with Hewlett-Packard’s Multiprotocol Advanced Communications Controller (ACC) multiplexer products. This manual applies to the ACC Protocols for Application Developers product. This manual explains installing the HDLC/LAP-B (ABM) protocol module and configuring it into the Multiprotocol ACC product.
Related Documentation The documentation available for the Multiprotocol ACC family of products includes the following hardware and software manuals: Hardware Manuals • 8 Channel PCI ACC Multiplexer Hardware Installation and Reference Manual Software Manuals • • • • • • • • • • • • • 8 ACC Installation and Configuration Guide ACC Utilities Reference Guide ACC Programmer’s Reference Guide ACC Error Guide HDLC Frame Protocol User’s Guide ACC X.25 Protocol User’s Guide ACC X.
Contents 1. Overview Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Product Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Supported Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Modes of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Contents 4. Protocol Specific Configuration Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Interface-Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Port-Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Terminal-Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1 Chapter 1 Overview 11
Overview Introduction Introduction The HDLC/LAP-B (ABM) Protocol product is the Data Link or Level 2 layer used in conjunction with the Advanced Communications Controller (ACC) product family. The ITU (CCITT) recommends the Link Access Procedure Balanced (LAPB) protocol for frame-level information transfers on balanced data links (two data stations) in X.25 packet-switching networks.
Overview Product Features Product Features This software provides Level 2 interface operation within the BAC class of procedures recommended by ITU-T (CCITT). As described in the standards cited below, BAC (Balanced operation Asynchronous balanced mode Class) applies to point-to-point configurations involving two combined stations on a logical data link. Unlike primary/secondary stations, these may have an equal (balanced) stake in the responsibility for data link management.
Overview Supported Devices Supported Devices Any device which conforms to the published HDLC/LAP-B (ABM) standards will be supported by this implementation.
Overview Modes of Operation Modes of Operation As recommended by ITU-T, the BAC class of procedure involves two combined stations operating in the Asynchronous Balanced Mode in either two-way alternate or two-way simultaneous (half-duplex or duplex) point-to-point configuration. Combined stations are characterized by the ability to send both commands and responses, receive both commands and responses, and provide for data link error recovery.
Overview Files Provided Files Provided The HDLC/LAP-B (ABM) Protocol product provides a pre-loaded firmware file that can be used directly in the ACC network configuration files. The HDLC/LAP-B (ABM) protocol may also be used on the same ACC Multiplexer as other protocols. If this is the case, a new firmware download (.zabs) file can be built to contain all of the protocols that will be used on that Mux card. This product provides the relocatable firmware files and a sample Link command (.
Overview References References For information on installing the ACC product, how to Link the relocatable firmware files, and how to start up the ACC Subsystem, refer to the ACC Installation and Configuration Guide. For information on using the ZCOM Application Programmatic Interface (API), refer to the ACC Programmer’s Reference Guide. For information on using the utilities related to the ACC products, refer to the ACC Utilities Reference Guide. For information on using the X.
Overview References 18 Chapter 1
2 Chapter 2 Software Installation and Verification 19
Software Installation and Verification Introduction Introduction The HDLC/LAP-B (ABM) protocol is included in the ACC Developer Software Suite product. This chapter describes how to install the product using the swinstall utility. It also describes how to verify that the protocol has been successfully installed and is functional.
Software Installation and Verification Software Removal Software Removal Step 1. If a previous version of the HDLC/LAP-B protocol product is already on the HP-UX system, it should first be removed. It is very important to follow the instructions provided with the software that is currently installed in the system to shutdown and remove that software. This procedure may change between major releases of the product. Log in to the system as superuser. Step 2.
Software Installation and Verification Software Installation Software Installation Running Swinstall The ACC software is read from the HP-UX Application CD-ROM, in superuser mode, using the swinstall utility. The steps are shown below. Step 1. Log in to the system as “root”. Step 2. Place the media in a local or remote CD-ROM drive. Step 3. Run swinstall, which behaves the same in the GUI interface as for the terminal interface.
Software Installation and Verification Product Identification Product Identification The what utility can be run on /opt/acc//hdlc.zabs or /opt/acc/protocol/hdlcabm.zrel to show what version of the protocols is installed.
Software Installation and Verification Installation Verification Installation Verification A sample configuration file /opt/acc/cfg/lapb_sample.answ file is provided with the ACC Developer Software Suite product. This sample file can be used to verify that the HDLC/LAP-B (ABM) protocol module has been properly installed and is functional. Note that you may need to customize this file, to reflect the location of the mux card(s) and to reflect the mux ports to be used. The lapb_sample.
Software Installation and Verification Installation Verification Verification Procedure The procedure described involves using the zmlog, ttgen, zmntr, and zterm utilities. These utilities are described in the ACC Utilities Reference Guide. Step 1. Modify the interface definition statement in the /opt/acc/cfg/lapb_sample.answ to reflect the location of the ACC Mux cards if necessary. (Refer to Chapter 4, Protocol Specific Configuration, in this manual for information on how to modify this statement.
Software Installation and Verification Installation Verification ------------------------------------------------------------------MON JUN 16 13:36:25 1998: ZMLOG: MESSAGE LOGGING RESUMED ------------------------------------------------------------------13:36:11 ZNODE 00109 zcom SYSTEM DOWN, EXITING 13:36:11 ZMAST 00129 STOPPING ZMLOG DAEMON. 13:36:11 ZMON 00049 END OF zMON REQUEST, PROGRAM TERMINATED 13:36:11 ZMON 00075 zcom SYSTEM STOPPED 13:36:24 ZMAST 00101 LAUNCHED DAEMON ZMLOG, PID 1433.
Software Installation and Verification Installation Verification Step 7. The zmntr utility can be used to observe the state of the link: ZMNTR> tt 10 20 ZLU# MX P:SC TERMINAL DESCRIPTION.. 0010 00 0:00 HDLC LINK 1 0020 00 1:00 HDLC LINK 2 **** ** ** MESSAGE TOTALS ZMNTR> EX RX.MES TX.MES ERRORS E.RATE STATE....... 0 0 0 0.00% DEACTIVATED 0 0 0 0.00% DEACTIVATED 0 0 0 NAN% ************ Step 8.
Software Installation and Verification Installation Verification Step 11. The sent data can now be received and displayed: ZTERM> rx list 13:44:51 Msg from tmnl ZLU#00020(00123) Lcn .00. .01. .02. .03. .04. .05. .06. 000 5A74 3031 3534 3100 206D 6573 7361 010 2030 3030 3031 206C 656E 6774 6820 020 6F70 7172 7374 7576 7758 13:44:51 Msg from tmnl ZLU#00020(00123) Lcn .00. .01. .02. .03. .04. .05. .06.
3 Chapter 3 Using HDLC/LAP-B (ABM) Protocol 29
Using HDLC/LAP-B (ABM) Protocol Introduction Introduction For a complete description of the communication formats, refer to the standards documents mentioned at the start of this manual. Each unit transmitted over an HDLC/LAP-B (ABM) link is a “frame”. A frame has an address field, a control field and a trailing CRC (Frame Check Sequence), is preceded and followed by a flag byte (binary 01111110), and may include an 'I' (information) field as well.
Using HDLC/LAP-B (ABM) Protocol Application Message Headers Application Message Headers Normal HDLC/LAP-B (ABM) Mode All application data is transmitted (or received) as the I-field of an information frame. All headers and/or trailers are supplied by the protocol for outgoing messages and removed by the protocol for incoming messages. Only the I-field data to be transferred is dealt with by the application program, which need not even be aware that HDLC/LAP-B (ABM) is being used for the communications.
Using HDLC/LAP-B (ABM) Protocol Timeout Processing Timeout Processing Frame timeouts are set in the Poll and Select configuration words. The T1 timer defines the period within which a response to a Command frame must be received across the HDLC/LAP-B (ABM) link. Should this timer expire before the expected response is received, then the Command frame will be re-transmitted up to a pre-determined maximum number of times (N2).
Using HDLC/LAP-B (ABM) Protocol Request Specific Processing Request Specific Processing Control Requests All control writes to this protocol share a common format as shown in Figure 3-1. Control writes are issued to the card using the zcntl() API call. Figure 3-1 Control Request Format 15 14 13 12 Control Code Packet Length 11 10 9 8 7 6 5 4 3 2 1 0 Control Length (0) The first four bytes are defined as a header: Chapter 3 Control Code Defines the action to be taken by this request.
Using HDLC/LAP-B (ABM) Protocol Request Specific Processing Control Codes This protocol allows the following Control Codes: 5 CW_STATS Send ST25L2STAT status message This control write triggers the protocol to send a ST25L2STAT status message. For the format of this message, see the section on “Status and Error Messages”. Control length must be zero. 6 CW_REVCODE Send ST25REVCD status message This control write triggers the protocol to send a ST25REVCD status message.
Using HDLC/LAP-B (ABM) Protocol Request Specific Processing The first pair of bytes applies to T1, the second pair is ignored (should be set to zero) and the third pair apply to T3/T4. See Figure 3-2 on page 35.
Using HDLC/LAP-B (ABM) Protocol Status and Error Messages Status and Error Messages HDLC/LAP-B (ABM) makes use of a range of message status codes and unsolicited status messages, other than the standard status codes described in the ACC Error Guide. The definitions for these status codes are located in /usr/include/zcomstatus.h and /usr/include/zcom/zx25status.h.
Using HDLC/LAP-B (ABM) Protocol Status and Error Messages Unsolicited Status Messages This section describes the unsolicited status messages which may be received on the ZLU which is set as the receiver for a terminal using this protocol. The status codes received may or may not have bit 7 set. Bit 7 is the down bit (masked by IO_DOWN_MASK). The down bit is used as an indicator of the link status.
Using HDLC/LAP-B (ABM) Protocol Status and Error Messages 65 ST25DSBL Link disconnected on DISABLE This status message is generated in response to a terminal disable request after multiple frame acknowledged operation has terminated. The down bit will always be set. 77 ST25ENF ENABLE failed - bad config This status message is generated in response to a terminal enable request when the terminal’s configuration is invalid. The down bit will always be set.
Using HDLC/LAP-B (ABM) Protocol Status and Error Messages 69 ST25TXFR Reset/Disc. due to transmitted FRMR A frame containing an error was received by the protocol; this causes LAP-B to reset the link by sending a FRMR. For consistent error handling between LAP-B and LAP-D (which sends a SABME instead of a FRMR), the latter protocol sends this status message. (The data buffer contains the information field of the FRMR that LAP-B would send.) 70 ST25RXFR Reset/Disc.
Using HDLC/LAP-B (ABM) Protocol Status and Error Messages The following status messages are used by the protocol on E1/T1 hardware to return data in response to a control write: 88 ST25L2STAT Statistics upload This message is sent in response to a CW_STATS control write. The data buffer contains a x25l2stat_type structure (defined in /usr/include/zcom/zcomx25.h). 89 ST25REVCD Revision code upload This message is sent in response to a CW_REVCODE control write.
Using HDLC/LAP-B (ABM) Protocol Status and Error Messages Control Write Completion Status Codes The following statuses are returned by the LAP-B protocol on E1/T1 hardware in response to control write requests. Although these are a part of the standard status set, they are not used by all protocols, and have a particular significance within this protocol. 0 IO_OK No error detected The request was successfully transmitted and acknowledged by the remote side.
Using HDLC/LAP-B (ABM) Protocol Status and Error Messages Read Completion Status Codes All receive completion messages will have the status IO_OK. Received messages that have errors are not returned by the protocol.
4 Chapter 4 Protocol Specific Configuration 43
Protocol Specific Configuration Introduction Introduction This section provides specific information on preparing the network configuration file when HDLC/LAP-B (ABM) is to be used.The parts of the network configuration (.
Protocol Specific Configuration Interface-Definition Interface-Definition An Interface-Definition line appears in the network configuration file for each ACC card that will have LAP-B (ABM) connections configured on it. It is possible to use other protocols with HDLC/LAP-B (ABM) on a single card, provided the firmware file has been customized to include those other protocols.
Protocol Specific Configuration Port-Definition Port-Definition On 8-port cards, the port must be defined as operating in SDLC mode. The ACC cards may use either an external (modem supplied) clock, or an internal (card supplied) clock. With an external (modem supplied) clock, the speed is for documentation purposes only, and will not be used by the ZCOM system. The clock multiplier should be x1, and the encoding mode would normally be NRZ (although NRZI may be used).
Protocol Specific Configuration Terminal-Definition Terminal-Definition Each HDLC/LAP-B (ABM) port or E1/T1 subchannel requires one (and only one) Terminal-Definition for the HDLC/LAP-B (ABM) point-to-point link. The LAP-B terminal is defined by a TERM line in the LAP-B sample file (lapb_sample.answ). Some sample HDLC/LAP-B (ABM) Terminal-Definition lines follow: Term 120 1:6 HDLC.
Protocol Specific Configuration Terminal-Definition Config This configuration keyword supplies the ‘POLL’ and ‘SELECT’ parameters for the ZCOM terminal definition. These are used to specify: • • • • • whether the HDLC/LAP-B (ABM) terminal acts as a DTE or DCE, the frame re-transmission time-out value, the re-transmission count limit, the outstanding frame window size to be used, the maximum frame size allowed. In most cases a pre-configured keyword will suffice.
Protocol Specific Configuration Predefined Configuration Values Predefined Configuration Values The following configuration values are currently defined for use in HDLC/LAP-B (ABM) configuration as a replacement for the POLL and SELECT address fields. These values are used (for example HDLC_DTE_3.0) as a symbolic way of configuring the associated two 16-bit hexadecimal values.
Protocol Specific Configuration Predefined Configuration Values NOTE 50 Specific user defined configurations may be added to the network configuration file. These configuration should use the #define statement and be placed at the beginning of the file. Refer to the examples in the file /opt/acc/cfg/ttgendefine.
Protocol Specific Configuration Poll/Select Configuration Values Poll/Select Configuration Values Poll Word DTE/DCE Operating mode - DTE or DCE Max I-field Largest I-field allowed (in bytes) Select Word T1 L2 acknowledgment Timer K Frame level Tx window N2 Number of Tx retries allowed Poll Word Figure 4-1 Poll Word Format 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 T/C -0- Maximum I-Field size (1-16383 bytes) See following note.
Protocol Specific Configuration Poll/Select Configuration Values Select Word Figure 4-2 Select Word Format 15 14 13 12 11 10 T1 Res T1÷2 (1-63) 52 9 8 7 6 K (0-7) 5 4 3 2 1 0 N2 (1-31) T1÷2 This is the value of the T1 timer (divided by two). The valid range is 1 to 63; 0 is not allowed and is an error. The units are given by the T1 Res (resolution) field (see below). T1 Res Resolution of the T1 value above.
Protocol Specific Configuration Poll/Select Configuration Values Option Word Figure 4-3 Option Word Format 15 14 13 Reserved Chapter 4 12 11 10 9 8 7 6 5 4 3 2 1 0 IUF Extended K IUF Error handling, normal when 0. This means normal error handling (level 2 link reset) on receipt of unsolicited response frame with F=1. 1 means Ignore F=1 (treat as F=0) in any unsolicited response frames. Extended K Window size for extended sequence numbering.
Protocol Specific Configuration Poll/Select Configuration Values 54 Chapter 4
A Appendix A Sample Configuration Files 55
Sample Configuration Files Sample Network Configuration (.answ) file Sample Network Configuration (.answ) file The file shown below represents the sample network configuration (.answ) file that is provided with the HDLC/LAP-B (ABM) protocol product.
