Avaya X.25 User's Manual
Contents
1. Configuring X 25 Gateway Services BayRS Version 12 00 Site Manager Software Version 6 00 Part No 117378 A Rev A September 1997 sa Bay Networks sa Bay Networks 4401 Great America Parkway 8 Federal Street Santa Clara CA 95054 Billerica MA 01821 Copyright 1997 Bay Networks Inc All rights reserved Printed in the USA September 1997 The information in this document is subject to change without notice The statements configurations technical data and recommendations in this document are believed to be accurate and reliable but are presented without express or implied warranty Users must take full responsibility for their applications of any products specified in this document The information in this document is proprietary to Bay Networks Inc The software described in this document is furnished under a license agreement and may only be used in accordance with the terms of that license A summary of the Software License is included in this document Trademarks Bay Networks is a registered trademark and Bay Networks Press and the Bay Networks logo are trademarks of Bay Networks Inc All other trademarks and registered trademarks are the property of their respective owners Restricted Rights Legend Use duplication or disclosure by the United States Government is subject to restrictions as set forth in subparagraph c 1 1 of the Rights in Technical Data and Computer Software clause at DFARS 252 227 70132. Function Instructions Destination Connection Type None SVC PVC Specifies either SVC or PVC as the destination connection for this TCP source connection Choose the value that applies to your network 1 3 6 1 4 1 18 3 5 15 2 1 8 Note Either the source or the destination connection type but not both must be TCP Parameter Default Options Function Instructions Destination PVC LCN None 1 to 4095 Specifies the PVC LCN that you map to the TCP connection The port monitors the X 25 calls for this LCN to initiate the connection This window appears only if you chose PVC as your source connection type Enter the LCN of the PVC for this IPEX connection Replicating a Configuration After you have configured one PVC to TCP or TCP to PVC connection you can copy that configuration and apply it to other connections rather than configuring the mappings one at a time If you need to customize some of the connections you can edit them later Note The Copy function works when one end of a connection is a PVC and the other is TCP It does not work with SVC connections Use the Copy button in the IPEX Mapping Table Configuration window Figure 2 5 to replicate a configuration The window is the same for both PVC to TCP and TCP to PVC connections the information the window displays varies according to the configuration 2 12 117378 A Rev A Enabling X 25 Gateway Done Gateway PVC
3. Notwithstanding any other license agreement that may pertain to or accompany the delivery of this computer software the rights of the United States Government regarding its use reproduction and disclosure are as set forth in the Commercial Computer Software Restricted Rights clause at FAR 52 227 19 Statement of Conditions In the interest of improving internal design operational function and or reliability Bay Networks Inc reserves the right to make changes to the products described in this document without notice Bay Networks Inc does not assume any liability that may occur due to the use or application of the product s or circuit layout s described herein Portions of the code in this software product are Copyright 1988 Regents of the University of California All rights reserved Redistribution and use in source and binary forms of such portions are permitted provided that the above copyright notice and this paragraph are duplicated in all such forms and that any documentation advertising materials and other materials related to such distribution and use acknowledge that such portions of the software were developed by the University of California Berkeley The name of the University may not be used to endorse or promote products derived from such portions of the software without specific prior written permission SUCH PORTIONS OF THE SOFTWARE ARE PROVIDED AS IS AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES INCLUDING W
4. Source X 121 Address Destination X 121 Address X 25 Call User Data Figure 2 4 IPEX Mapping Parameters Window for TCP Parameters for PVC and SVC Connections Parameter descriptions for PVC and SVC connections follow Parameter Default Options Function Instructions MIB Object ID Source PVC LCN None 1 to 4095 Specifies the inbound PVC LCN that you map to the TCP connection The port monitors the X 25 calls for this LCN to initiate the connection This window appears only if you chose PVC as your source connection type Enter the LCN of the PVC for this IPEX connection 9999 109 1 117378 A Rev A 2 9 Configuring X 25 Gateway Services Parameter Default Options Function Instructions MIB Object ID Parameter Default Options Function Instructions MIB Object ID X 121 Called Address None Any valid X 121 address Specifies the inbound X 121 called address that you map to the TCP connection The port monitors the X 25 calls for this X 121 called address to initiate the connection This window appears only if you chose SVC as your source connection type Enter the called X 121 address up to 15 decimal digits The destination address depends on the network device to which this circuit is connected Consult your network administrator for the correct value 1 3 6 1 4 18 3 5 15 2 1 6 Remote IP Address None Any valid IP address Specifies the remote IP address u
5. TCP Initiated 1 10 Role of the X 25 and TCP Protocol Stacks in X 25 Gateway 1 11 IPEX Mapping Add Window for Source PVC se 2 3 IPEX Mapping Parameters Window for PVC TT 2 8 IPEX Mapping Parameters Window for SVG esee 2 8 IPEX Mapping Parameters Window for TOP sse 2 9 IPEX Mapping Table Configuration Window esseeeees 2 13 IPEX Mapping Replication Minden nenn E Ebert prep 2 15 IPEX Mapping Table Configuration Window After Replicating a Pts TOP Co Me UO TT 2 16 IPEX Mapping Table Configuration Window After Replicating a HOPG 9 TION ee 2 17 vii About This Guide If you are responsible for configuring X 25 Gateway services you need to read this guide If you want to Go to Learn about the X 25 Gateway protocol and special aspects of the Bay Chapter 1 Networks implementation of X 25 Gateway Start X 25 Gateway on a router and configure Gateway parameters Chapter 2 Before You Begin Before using this guide you must complete the following procedures For a new router Install the router refer to the installation manual that came with your router Connect the router to the network and create a pilot configuration file refer to Quick Starting Routers Configuring BayStack Remote Access or Connecting ASN Routers to a Network Make sure that you are running the la
6. A larger message block may be transmitted in several TCP data segments With the 2 byte length field the maximum length of a message block that X 25 Gateway can send and receive using TCP is 64 KB Note While the maximum length of the X 25 message that X 25 Gateway can send to the terminal is 64 KB the maximum length of the X 25 message that X 25 Gateway can receive from the terminal is 4 KB 117378 A Rev A 1 13 Chapter 2 Enabling X 25 Gateway This chapter as outlined in the following table describes how to use the Configuration Manager to set up X 25 Gateway services Section Page Preparing a Configuration File 2 1 Configuring X 25 IPEX Services 2 1 Enabling X 25 Gateway Services 2 2 Adding an Entry to the IPEX Mapping Table 2 2 Complete the following steps to configure IPEX mapping parameters 2 7 Preparing a Configuration File Before you configure X 25 Gateway 1 Create and save a configuration file that has at least one WAN interface 2 Retrieve the configuration file in local remote or dynamic mode 3 Specify router hardware if this is a local mode configuration file Refer to Configuring and Managing Routers with Site Manager for instructions Configuring X 25 IPEX Services When you enable X 25 Gateway services you must configure X 25 IPEX services Refer to Chapters 3 and 4 of Configuring X 25 Services for instructions on enabling X 25 and editing
7. Help 117378 A Rev A 2 15 Configuring X 25 Gateway Services Done Gateway PVC TCP LCN 1 src cct MCT1 21 1 Gateway PYC gt TCP LCN 2 src cct MCT1 21 1 Gateway PVC gt TCP LCN 3 src cct MCT1 21 1 Gateway PYC gt TCP LCN 4 src cct MCTi1 21 1 Gateway PYC gt TCP LCN 5 src cct MCT1 21 1 Gateway PVC TCP LCN 6 src cct MCT1 21 1 Gateway PVC TCP LCN 7 src cct MhMCT1 21 1 Gateway PVC TCP LCN 8 src cct MCT1 21 1 Gateway PVC TCP LCN 9 src cct MCTi1 21 1 Gateway PVC TCP LCN 10 src cct MCT1 21 1 Help hi n d t Add Copy Delete Apply Values po o o o Je 0 fe Enable ENABLE j Source X 121 Address Destination X 121 Address Destination PVC LCN Remote IP Address Remote TCP Port Number Figure 2 7 IPEX Mapping Table Configuration Window After Replicating a PVC to TCP Connection 2 16 117378 A Rev A Enabling X 25 Gateway Gateway ICP PVC Port 12305 src cct MCT1 21 PENE Gateway TCP gt PYC Port 12306 src cct MCT1 21 fidd Gateway TCP gt PYC Port 12307 src cct MCT1 21 Gateway TCP gt PVC Port 12308 src cct MCT1 21 Copy Gateway TCP gt PVC Port 12309 src cct MCT1 21 Delete Gateway TCP gt PYC Port 12310 src cct MCT1 21 Gateway TCP PVC Port 12311 src cct MCT1 21 Apply Gateway TCP gt PYC Port 12312 src cct MCT1 21 Gateway TCP gt PYC Port 12313 src cct MCT1 21 Values Help pad u a Enable ENABLE Source X 1
8. TCP LCN 1 src cct MCT1 21 1 c Add Copy Delete Apply Values Help LL at Enable ENABLE u Source X 121 Address Destination X 121 Address Destination PVC LCN Remote IP Address Remote TCP Port Number Figure 2 5 IPEX Mapping Table Configuration Window To replicate a PVC to TCP or TCP to PVC configuration complete the tasks in the following table 117378 A Rev A 2 13 Configuring X 25 Gateway Services Site Manager Procedure You do this System responds 1 Choose the configuration you want to replicate and click on Copy The IPEX Mapping Replication window opens Figure 2 6 2 Set the following parameters Click on Help or see the parameter descriptions beginning on 2 18 Number of instances First LCN number First TCP port number TCP port number increment 3 Click on OK The IPEX Mapping Table Configuration window reopens Figure 2 7 for PVC to TCP Figure 2 8 for TCP to PVC It now lists all of the connections you have configured with the Copy button 4 Click on Done You return to the X 25 Service Configuration window 5 Click on Done You return to the main Configuration Manager window 2 14 117378 A Rev A Number of instances First LCN number First TCP port number TCP port number increment Figure 2 6 IPEX Mapping Replication Window Enabling X 25 Gateway Cancel OK Values
9. a failure at either the X 25 Gateway or remote TCP IP host interface X 25 TCP IP er host ee X 25 ae terminal 6s m X 25 TCP interface connections down reestablished X250025A Figure 1 4 Reestablishing TCP IP Connections Establishing Connections from the TCP IP Host When a TCP IP based system issues a connection request X 25 Gateway performs the sequence of actions shown in 1 5 117378 A Rev A 1 9 Configuring X 25 Gateway Services X 25 TCP IP yon X 25 host terminal res Step 1 gt O Connection CS requested X 25 TCP IP el X 25 host terminal E Request X 25 pending connection X 25 attempt TCP IP a X 25 host terminal rej Step 3 7 I Reguest X 25 pending connection X 25 accepted TCP IP an X 25 host terminal Tes Step 4 a Reguest X 25 accepted connection established X250026A Figure 1 5 How X 25 Gateway Establishes a Session TCP Initiated After establishing the X 25 connection X 25 Gateway accepts the TCP connection This one to one connection mapping provides another consistent and reliable session The mapping information you need to configure is e The circuit interface on which X 25 Gateway establishes the TCP connection e The TCP port number t
10. c to use and copy the associated user manual solely in support of authorized use of the Software by Licensee This license applies to the Software only and does not extend to Bay Networks Agent software or other Bay Networks software products Bay Networks Agent software or other Bay Networks software products are licensed for use under the terms of the applicable Bay Networks Inc Software License Agreement that accompanies such software and upon payment by the end user of the applicable license fees for such software 2 Restrictions on use reservation of rights The Software and user manuals are protected under copyright laws Bay Networks and or its licensors retain all title and ownership in both the Software and user manuals including any revisions made by Bay Networks or its licensors The copyright notice must be reproduced and included with any copy of any portion of the Software or user manuals Licensee may not modify translate decompile disassemble use for any competitive analysis reverse engineer distribute or create derivative works from the Software or user manuals or any copy in whole or in part Except as expressly provided in this Agreement Licensee may not copy or transfer the Software or user manuals in whole or in part The Software and user manuals embody Bay Networks and its licensors confidential and proprietary intellectual property Licensee shall not sublicense assign or otherwise disclose to any third party the So
11. for transmission Process received data delivered from the X 25 module Control the flow of data across the client interface X 25 Level 2 LAPB Only Interface X 25 Gateway also supports a direct LAPB interface so terminals can transfer data in LAPB format without using the X 25 packet layer You can select specific LAPB link circuits for the translation service to use instead of the X 25 PLP 117378 A Rev A 1 3 Configuring X 25 Gateway Services TCP Interface X 25 Gateway appears to TCP as a client As such the software specifies one socket for the local TCP interface consisting of its IP address and TCP port number and another socket for the remote TCP interface to establish a connection Each X 25 connection corresponds to only one TCP connection Since many TCP connections may be active concurrently to support many Gateway sessions a large range of TCP port numbers creates separate sockets for individual sessions The port numbers reserved for X 25 Gateway service are 12 304 to 16 399 X 25 Gateway uses the TCP client interface to e Open close and check the status of TCP connections e Send data to the TCP module for transmission Process received data delivered from the TCP module e Control the flow of data across the client interface What X 25 Gateway Does X 25 Gateway consists of a source circuit and a destination circuit The gateway receives the first incoming connection on the source circuit and a
12. is a corresponding TCP connection set up between X 25 Gateway and the TCP IP peer This connection remains established until either The X 25 equipment resets the PVC connection The X 25 interface is restarted e The TCP peer terminates the TCP connection The mapping information that you must configure is e The circuit interface for the PVC connection e The logical channel number LCN of the PVC connection e The associated remote TCP socket IP address and TCP port number that identifies the remote end of the TCP connection 117378 A Rev A 1 7 Configuring X 25 Gateway Services Establishing Connections from the X 25 Level 2 LAPB Terminal The router uses a similar procedure for establishing LAPB to TCP connections You must specify the mapping information needed to configure the connection specifically e The circuit interface through which X 25 Gateway will establish a LAPB connection e Its associated remote TCP socket which identifies the remote end of the TCP connection This mapping information sets up the path for forwarding data traffic received in a LAPB circuit to a specific remote TCP IP server and for forwarding data traffic received from a TCP connection to a specific LAPB circuit When it has established this LAPB to TCP translation session X 25 Gateway translates the LAPB information frames it receives from the LAPB terminals into TCP data segments and vice versa Establishing Connections During
13. request a connection The software relies on a set of configured mapping parameters to associate the X 25 connection on one side of the router to the TCP connection on the other side In response to a connection request from the X 25 equipment the router establishes a connection to a TCP IP server When this TCP connection is established the router accepts the X 25 connection attempt This one to one connection mapping creates a consistent and reliable Gateway session The types of X 25 connections that X 25 Gateway supports include Switched virtual circuits SVCs Switched virtual circuits with no X 121 called address e Permanent virtual circuits PVCs With an X 25 Level 3 interface you can establish a switched virtual circuit or a permanent virtual circuit between the X 25 equipment and the TCP based system An SVC is a temporary logical connection It may or may not have a called address associated with it depending on whether the type of connection that you configured required an X 121 called address The following sections describe what you configure for each of these connections SVCs With a Called X 121 Address To establish an SVC connection that contains a specified X 25 called address X 121 address you configure mapping information that X 25 Gateway uses to set a path for forwarding data traffic received on an X 25 SVC to a specific remote TCP IP peer The remote TCP IP peer has an IP address and TCP port number tha
14. support With this configuration the router translates data received from LAPB connections to TCP data packets and forwards those packets out through TCP connections It also translates data received from TCP connections to LAPB data and forwards the data out through LAPB connections 1 2 117378 A Rev A X 25 Gateway Overview Network Interfaces Bay Networks routers that support X 25 Gateway services use the following protocols e X 25 Level 3 Packet Layer Protocol PLP e X 25 Level 2 Protocol LAPB e Transmission Control Protocol TCP e Internet Protocol IP X 25 Level 3 PLP Interface On an X 25 Level 3 interface you can create and configure multiple virtual circuits including e Permanent virtual circuits Switched virtual circuits with or without called X 121 addresses You can create a set of either of these connections or a combination of the two On any X 25 interface you can configure either X 25 Gateway service or other types of X 25 services such as Public Data Network PDN Point to Point PToP and Defense Data Network DDN If you configure X 25 Gateway service on an X 25 interface the software translates data sent and received between the X 25 network interface and the TCP IP network interface It uses X 25 flow control mechanisms to detect congestion in the X 25 connection X 25 Gateway uses the X 25 Level 3 client interface to e Open and close X 25 connections e Send data to the X 25 module
15. 1 1 shows a topology consisting of two Bay Networks router systems and a TCP IP network The top system serves as a TCP IP to X 25 gateway The bottom system serves as a TCP IP to LAPB gateway In this example terminals connected to X 25 networks can exchange messages with host systems on a TCP IP network through the Bay Networks routers using the X 25 Gateway service X 25 nn TCP ie X 25 Level3 Qateway terminals conncallene router _ connections TCP IP host 0O ama X 25 NM d V 35 or m Lam T1 links V 35 or N Be H TCP IP X 25 h EN LAPB 4 gateway gt concentrator X 25 Level router Physical LAPB V 35 links connections X250022A Figure 1 1 Sample Network Topology Using X 25 Gateway The router translates data received from X 25 virtual connections into TCP data packets and forwards those packets out through TCP connections The router also translates data received from TCP connections into X 25 data and forwards the data out through X 25 connections You can connect the equipment to the router by a leased line an X 25 packet switched network or a T1 or E1 circuit switched network You can also configure the router as a TCP IP to CCITT now ITU T X 25 Level 2 gateway as in the bottom part of Figure 1 1 This configuration allows access from LAPB based X 25 Level 2 equipment with no X 25 Level 3 support This manual refers to this feature as LAPB only
16. 21 Address Destination X 121 Address Destination PVC LCN Remote IP Address Remote TCP Port Number Figure 2 8 IPEX Mapping Table Configuration Window After Replicating a TCP to PVC Connection 117378 A Rev A 2 17 Configuring X 25 Gateway Services Parameters for Replicating Connections Parameter Default Options Function Instructions Parameter Default Options Function Instructions Parameter Default Options Function Instructions Number of Instances None 1 to 9 for a FRE2 040 32MB platform 1 to 31 for a FRE2 060 64MB platform Specifies the number of connections to be replicated The maximum number of VCs per channel for the FRE2 040 32MB platform is 10 so you can make up to 9 replicates for the FRE1 060 64MB platform the maximum is 32 so you can make up to 31 replicates Enter the number of PVC to TCP or TCP to PVC replicate connections you want to configure First LCN number None 2 to 10 for a FRE2 040 32MB platform 2 to 32 for a FRE2 060 64MB platform Identifies the LCN number of the first PVC that will use the replicate configuration Each LCN number on a channel must be unique The options given above assume that you have assigned an LCN number of 1 for the PVC that you are using as the source for replicates Enter the LCN number First TCP port number None For a PVC to TCP connection this value can be any valid port number For a TCP to PVC connecti
17. Failure Conditions for PVC TCP Translation The X 25 Gateway software running on X 25 PVC devices is able to reestablish a connection when a fault occurs at the TCP IP or X 25 physical layer You do not have to enable or configure this feature The figures below show how the software reestablishes a connection between X 25 and TCP IP Reestablishing the X 25 Connection When a physical layer fault occurs a disconnected cable at the X 25 interface Figure 1 3 X 25 Gateway disconnects the associated TCP connections It reestablishes the TCP connections to the mapped X 25 virtual circuits when the X 25 interface is again available 1 8 117378 A Rev A X 25 Gateway Overview X 25 TCP IP gateway host TORO X 25 EL JL terminal pd T p EM C TCP X 25 connections interface L 3 reset down X250024A Figure 1 3 Reestablishing X 25 Connections Reestablishing the TCP IP Connection In the event of a physical layer fault on the TCP IP interface Figure 1 4 X 25 Gateway resets any established TCP connections as well as the X 25 connections associated with each TCP connection The software attempts to reestablish a TCP connection until the TCP interface is again available When TCP connections are available the software resets the X 25 connections to an operational state Examples of physical layer faults include a disconnected cable or
18. ILL BAY NETWORKS OR ITS LICENSORS BE LIABLE FOR ANY COST OF SUBSTITUTE PROCUREMENT SPECIAL INDIRECT INCIDENTAL OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES RESULTING FROM INACCURATE OR LOST DATA OR LOSS OF USE OR PROFITS ARISING OUT OF OR IN CONNECTION WITH THE PERFORMANCE OF THE SOFTWARE EVEN IF BAY NETWORKS HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES IN NO EVENT SHALL THE LIABILITY OF BAY NETWORKS RELATING TO THE SOFTWARE OR THIS AGREEMENT EXCEED THE PRICE PAID TO BAY NETWORKS FOR THE SOFTWARE LICENSE 5 Government Licensees This provision applies to all Software and documentation acquired directly or indirectly by or on behalf of the United States Government The Software and documentation are commercial products licensed on the open market at market prices and were developed entirely at private expense and without the use of any U S Government funds The license to the U S Government is granted only with restricted rights and use duplication or disclosure by the U S Government is subject to the restrictions set forth in subparagraph c 1 of the Commercial Computer Software Restricted Rights clause of FAR 52 227 19 and the limitations set out in this license for civilian agencies and subparagraph c 1 ii of the Rights in Technical Data and Computer Software clause of DFARS 252 227 7013 for agencies of the Department of Defense or their successors whichever is applicable 6 Use of Software in the European Community This pr
19. ITHOUT LIMITATION THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE In addition the program and information contained herein are licensed only pursuant to a license agreement that contains restrictions on use and disclosure that may incorporate by reference certain limitations and notices imposed by third parties 117378 A Rev A Bay Networks Inc Software License Agreement NOTICE Please carefully read this license agreement before copying or using the accompanying software or installing the hardware unit with pre enabled software each of which is referred to as Software in this Agreement BY COPYING OR USING THE SOFTWARE YOU ACCEPT ALL OF THE TERMS AND CONDITIONS OF THIS LICENSE AGREEMENT THE TERMS EXPRESSED IN THIS AGREEMENT ARE THE ONLY TERMS UNDER WHICH BAY NETWORKS WILL PERMIT YOU TO USE THE SOFTWARE If you do not accept these terms and conditions return the product unused and in the original shipping container within 30 days of purchase to obtain a credit for the full purchase price 1 License Grant Bay Networks Inc Bay Networks grants the end user of the Software Licensee a personal nonexclusive nontransferable license a to use the Software either on a single computer or if applicable on a single authorized device identified by host ID for which it was originally acquired b to copy the Software solely for backup purposes in support of authorized use of the Software and
20. ITU T LAN LAPB LCN MAN MIB MCTI MTU PDN PLP PPP PToP PVC SNMP SVC TCP TCP IP Telnet TFTP WAN About This Guide International Telegraph and Telephone Consultative Committee now ITU T data circuit terminating eguipment Defense Data Network data terminal eguipment Fiber Distributed Data Interface Internet Protocol IP Encapsulation of X 25 International Telecommunications Union Telecommunications formerly CCITT local area network Link Access Procedure Balanced logical channel number metropolitan area network Management Information Base Multichannel T1 maximum transmission unit Public Data Network Packet Layer Protocol Point to Point Protocol Point to Point Bay Networks proprietary permanent virtual circuit Simple Network Management Protocol switched virtual circuit Transmission Control Protocol Transmission Control Protocol Internet Protocol Telecommunication Network Trivial File Transfer Protocol wide area network 117378 A Rev A xi Configuring X 25 Gateway Services Ordering Bay Networks Publications To purchase additional copies of this document or other Bay Networks publications order by part number from Bay Networks Press at the following numbers e Phone U S Canada 888 422 9773 e Phone International 510 490 4752 e FAX U S Canada and International 510 498 2609 The Bay Networks Press catalog is available on the World Wide Web at support baynetworks com Li
21. PERSEDES ALL PRIOR ORAL AND WRITTEN AGREEMENTS AND COMMUNICATIONS BETWEEN THE PARTIES PERTAINING TO THE SUBJECT MATTER OF THIS AGREEMENT NO DIFFERENT OR ADDITIONAL TERMS WILL BE ENFORCEABLE AGAINST BAY NETWORKS UNLESS BAY NETWORKS GIVES ITS EXPRESS WRITTEN CONSENT INCLUDING AN EXPRESS WAIVER OF THE TERMS OF THIS AGREEMENT iv 117378 A Rev A Contents About This Guide PER AU EE nenne A ix Conventions E pan MN Eben E m x DENE neigen xi Ordering Bay Nebwolke PUDNC AMONG uses nenne xii Bay Nebworks Customer SBIVIDB etie ala xii FOR BSR HE m TU xiii Chapter 1 X 25 Gateway Overview Roe Garewal OPO lr c 1 2 SNS NEISSE in los oa k slo Sse Puer Ran OD k 1 3 24 Level S PLP Niere E 1 3 X25 Legal 2 ILAPB On Hess ae oido d E Rene RH bo d a ba 1 3 GS 0 10218 d eR 1 4 Wiat 2 Gateway DOGS ui 1 4 POCS Tane a ae E duc bi Fea EEA 1 4 Establishing Connections from the X 25 Equipment Spine EEE 1 6 mvs With a Galled X 121 Address une 1 6 SVCs Without a Called X 121 Address sse 1 7 Permanent Virtual Circuits PVCS ua 1 7 Establishing Connections from the X 25 Level 2 LAPB Terminal 1 7 Establishing Connections During Failure Conditions for PV TOF TIS DS aiina rd biennio est enr ca pong Hop abba it kb dl pondre 1 8 Heestablishing the X 25 Cornneglfoli aan 1 8 Reestablishing the TEPAP Oonfgellblt een cec b ke abiret rueda 1 9 Establishing Connections from t
22. Valbonne France 33 4 92 96 69 68 33 4 92 96 69 98 Sydney Australia 61 2 9927 8800 61 2 9927 8811 Tokyo Japan 81 3 5402 0180 81 3 5402 0173 117378 A Rev A xiii Chapter 1 X 25 Gateway Overview X 25 Gateway lets you send and receive messages between X 25 and Transmission Control Protocol Internet Protocol TCP IP networks It maps TCP sockets to X 25 virtual circuits and vice versa or to Link Access Procedure Balanced LAPB point to point connection identifiers The Gateway software supports X 25 permanent virtual circuits PVCs and switched virtual circuits SVCs as well as TCP IP over all interface types supported in the Bay Networks router X 25 Gateway supports e TCP IP over Fiber Distributed Data Interface FDDI Ethernet and token ring LAN media or over X 25 frame relay Asynchronous Transfer Mode ATM and switched multimegabit data service SMDS wide area network WAN or metropolitan area network MAN media e X25Levels 2 and 3 over synchronous interfaces 6 MB s and below or Multichannel T1 MCT1 interfaces e 10 VCs per logical channel for the FRE2 040 32MB platform for a total of 240VCs per slot e 32 VCs per channel for the FRE1 060 64MB for a total of 310VCs per slot Use Site Manager s Configuration Manager to configure a system for X 25 Gateway services 117378 A Rev A 1 1 Configuring X 25 Gateway Services X 25 Gateway Topology Figure
23. X 25 parameters Refer to Chapter 5 of that guide for instructions on configuring IPEX 117378 A Rev A 2 1 Configuring X 25 Gateway Services Enabling X 25 Gateway Services To enable X 25 Gateway services 1 Add an entry to the IPEX mapping table 2 Choose Gateway as the IPEX Mapping Type 3 Configure mapping parameters Use the following instructions to add an IPEX mapping entry and choose Gateway as the mapping type Adding an Entry to the IPEX Mapping Table Complete the following steps to add an entry to the IPEX mapping table Site Manager Procedure You do this System responds 1 In the Configuration Manager window The Circuit List window opens select Circuits Edit Circuits 2 Choose an X 25 interface then click on The Circuit Definition window opens Edit 3 Choose X25 Protocol Service The X 25 Service Configuration window appears It lists all currently defined network service records 4 Choose the network service record you want to configure for X 25 Gateway services 5 Click on Add The X 25 Service window opens Position your cursor in the Type parameter bar click on the Values button and choose IPEX as the service type 2 2 117378 A Rev A Enabling X 25 Gateway Site Manager Procedure continued You do this System responds T Edit the following parameters as appropriate to your network Use Help or see the parameter de
24. ateway Services The TCP and X 25 communication stacks share the responsibility for maintaining reliable and efficient data flow If data loss occurs on one side that side retransmits the lost data In addition both sides independently maintain protocol flow control Data loss may result from either software or hardware errors or catastrophic failures Redundancy in network design is critical for handling these types of data communication failures Handling Large Data Messages X 25 is a message based protocol and TCP is an unstructured stream protocol They differ in the way they send outgoing traffic and deliver incoming traffic to their clients How X 25 Handles Large Data Messages When the X 25 client submits an X 25 message that is larger than an X 25 packet size the X 25 protocol fragments the message X 25 then transmits the sequence of packets containing these fragments Within each packet X 25 includes a flag that indicates the fragmentation and aids in the reassembly process at the receiving end How TCP Handles Large Data Messages TCP on the other hand does not have a flag to mark fragmentation of messages that are larger than the TCP maximum transmission unit MTU size The portion that does not fit into one TCP data segment is sent in a subsequent data segment Without the flag and any indication of the size of the message the TCP client has no way of determining the boundary of a message that is whether the comple
25. brary GenMisc Bay Networks publications are available on the World Wide Web at support baynetworks com Library tpubs Bay Networks Customer Service You can purchase a support contract from your Bay Networks distributor or authorized reseller or directly from Bay Networks Services For information about or to purchase a Bay Networks service contract either call your local Bay Networks field sales office or one of the following numbers Region Telephone number Fax number United States and 800 2LANWAN then enter Express 978 916 3514 Canada Routing Code ERC 290 when prompted to purchase or renew a service contract 978 916 8880 direct Europe 33 4 92 96 69 66 33 4 92 96 69 96 Asia Pacific 61 2 9927 8888 61 2 9927 8899 Latin America 561 988 7661 561 988 7550 Information about customer service is also available on the World Wide Web at support baynetworks com xii 117378 A Rev A How to Get Help About This Guide If you purchased a service contract for your Bay Networks product from a distributor or authorized reseller contact the technical support staff for that distributor or reseller for assistance If you purchased a Bay Networks service program call one of the following Bay Networks Technical Solutions Centers Technical Solutions Center Telephone number Fax number Billerica MA 800 2LANWAN 978 916 3514 Santa Clara CA 800 2LANWAN 408 495 1188
26. ccident misuse or abuse The Licensee assumes all responsibility for selection of the Software to achieve Licensee s intended results and for the installation use and results obtained from the Software Bay Networks does not warrant a that the functions contained in the software will meet the Licensee s requirements b that the Software will operate in the hardware or software combinations that the Licensee may select c that the operation of the Software will be uninterrupted or error free or d that all defects in the operation of the Software will be corrected Bay Networks is not obligated to remedy any Software defect that cannot be reproduced with the latest Software release These warranties do not apply to the Software if it has been 1 altered except by Bay Networks or in accordance with its instructions ii used in conjunction with another vendor s product resulting in the defect or iii damaged by improper environment abuse misuse accident or negligence THE FOREGOING WARRANTIES AND LIMITATIONS ARE EXCLUSIVE REMEDIES AND ARE IN LIEU OF ALL OTHER WARRANTIES EXPRESS OR IMPLIED INCLUDING WITHOUT LIMITATION ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE Licensee is responsible for the security of 117378 A Rev A iii its own data and information and for maintaining adequate procedures apart from the Software to reconstruct lost or altered files data or programs 4 Limitation of liability IN NO EVENT W
27. cuit Select SVC to specify an X 25 connection to a switched virtual circuit Select TCP to specify a Transmission Control Protocol connection MIB Object ID 1 3 6 1 4 18 3 5 15 2 1 4 2 4 117378 A Rev A Parameter Default Options Function Instructions MIB Object ID Enabling X 25 Gateway Mapping Type End to End Local End to End Gateway Specifies whether facilities call user data and M bit and Q bit support terminate locally or are passed end to end X 25 parameters that you configure at the packet and service record level determine which facilities are supported The last option is to configure X 25 Gateway services If you set this parameter to Local IPEX ports can support different packet sizes at each end You must also configure the Source X 121 Address parameter for an SVC source connection type and both Source and Destination X 121 Address parameters for a TCP source connection type If you configure End to End mapping all IPEX ports must have the same packet and window size because different packet sizes cause M bit support to malfunction If you set this parameter to Gateway you use X 25 Gateway services X 25 terminates at the router interface but allows you to configure one of three message header types at the TCP application layer Choose Gateway 1 3 6 1 4 1 18 3 5 15 2 1 16 117378 A Rev A 2 5 Configuring X 25 Gateway Services Parameter Default Options Functio
28. ftware or any information about the operation design performance or implementation of the Software and user manuals that is confidential to Bay Networks and its licensors however Licensee may grant permission to its consultants subcontractors and agents to use the Software at Licensee s facility provided they have agreed to use the Software only in accordance with the terms of this license 3 Limited warranty Bay Networks warrants each item of Software as delivered by Bay Networks and properly installed and operated on Bay Networks hardware or other equipment it is originally licensed for to function substantially as described in its accompanying user manual during its warranty period which begins on the date Software is first shipped to Licensee If any item of Software fails to so function during its warranty period as the sole remedy Bay Networks will at its discretion provide a suitable fix patch or workaround for the problem that may be included in a future Software release Bay Networks further warrants to Licensee that the media on which the Software is provided will be free from defects in materials and workmanship under normal use for a period of 90 days from the date Software is first shipped to Licensee Bay Networks will replace defective media at no charge if it is returned to Bay Networks during the warranty period along with proof of the date of shipment This warranty does not apply if the media has been damaged as a result of a
29. hat uniquely identifies the translation session The type of connection SVC or PVC at the X 25 end of the connection e The logical channel number LCN of the PVC connection or the pair of calling and called X 121 addresses of the SVC connection 1 10 117378 A Rev A X 25 Gateway Overview After establishing this X 25 to TCP session X 25 Gateway translates X 25 Level 3 data packets received from the X 25 client terminals to TCP data segments and vice versa Connection Summary To set up a reliable X 25 Gateway session both sides must successfully establish the connections When one side receives a connection indication the other side initiates a connection attempt If the connection attempt fails on the far side the near side rejects the connection request it received Figure 1 6 shows how X 25 Gateway mediates the interaction between the two protocol stacks as the data flows between the X 25 client terminals and the TCP based hosts Information from to other Information TCP hosts from to other or other Gateway X 25 terminals routers l X 25 Gateway e N gt gt 2 LO te N N x x IEEE 802 2 eh X 25 level 3 n IP u sla SNMP X 25 level 2 M n IEEE 802 2 o Lu ul Lu V 35 IEEE 802 3 X9250013R Figure 1 6 Role of the X 25 and TCP Protocol Stacks in X 25 Gateway 117378 A Rev A 1 11 Configuring X 25 G
30. he TCP IP Host rrzurrsenrenennnnnnnnonennnenneen nenn nenn 1 9 Connection SUIm fartY aaa seien Tenn T irren 1 11 Handling Large Data Messages san ale 1 12 117378 A Rev A V How X 25 Handles Large Data Messages ssseeeeneeeeeeennen 1 12 How TCP Handles Large Data Messages ssssseeeeeeeeennne 1 12 X25 Gateway Message Block Opliane aan incre 1 13 Chapter 2 Enabling X 25 Gateway Preparing a Configuration File een M 2 1 Gong 4 5 PEX RES Lisci daas ee 2 1 Enabling X25 Gateway SASS are 2 2 Adding an Entry to the IPEX Mapping Table u a 2 2 Canfigaring Mapping Parameters sn 2 7 IPEX Mapping Parameters Windows sse Tm 2 7 Parameters for PVC and SVO Connecting ae 2 9 Paramore Tor TOP Connect DSi ana 2 11 Replicating a Configuration A eee er E ee 2 12 Parameters for Replicating Connections use 2 18 Index vi 117378 A Rev A Figure 1 1 Figure 1 2 Figure 1 3 Figure 1 4 Figure 1 5 Figure 1 6 Figure 2 1 Figure 2 2 Figure 2 3 Figure 2 4 Figure 2 5 Figure 2 6 Figure 2 7 Figure 2 8 117378 A Rev A Figures Sample Network Topology Using X 25 Gateway sssssssss 1 2 How X 25 Gateway Establishes a Session X 25 Initiated 1 5 Meestablehirg A 2a DOnbbolloltis una 1 8 Reestablishing TCP IP Gonnactions unse 1 9 How X 25 Gateway Establishes a Session
31. lp or see the parameter descriptions beginning on page 2 9 Parameters include Source PVC LCN X 121 Called Address Remote IP Address Remote TCP Port Number Local TCP Port Destination Connection Type Destination PVC LCN Click on OK The IPEX Mapping Table Configuration window reopens Click on Done The X 25 Gateway configuration is complete You return to the X 25 Service Configuration window To learn how to replicate this configuration for other PVC TCP connections see the later section of the guide Replicating a Configuration Otherwise click on Done You return to the main Configuration Manager window IPEX Mapping Parameters Windows In the appropriate IPEX Mapping Parameters window define a new mapping entry by specifying source and destination addresses the format of which depend on whether the connection type is PVC SVC or TCP 117378 A Rev A 2 7 Configuring X 25 Gateway Services Cancel OK Values Help Source PVC LCN Remote IP Address Remote TCP Port Number Figure 2 2 IPEX Mapping Parameters Window for PVC Cancel OK Values Help X 121 Called Address 1234567 Remote IP Address Remote TCP Port Number Figure 2 3 IPEX Mapping Parameters Window for SVC 2 8 117378 A Rev A Local TCP Port Enabling X 25 Gateway Cancel OK Values Help Destination Connection Type Destination PVC LCN
32. lutions Centers xiii D DCE interface 1 7 destination circuit definition of 1 4 Destination Connection Type parameter 2 12 Destination PVC LCN parameter 2 12 DTE interface 1 7 E Ethernet 1 1 F fault physical layer 1 8 FDDI 1 1 flow control 1 3 G Gateway definition of 1 1 H header message 1 13 I interface circuit 1 6 DCE 1 7 DTE 1 7 Index 1 TCP 1 4 IP Internet Protocol address 1 4 protocol 1 3 IPEX adding a mapping entry 2 2 mapping parameters configuring 2 7 requirement to configure 2 1 IPEX Mapping Add window 2 3 IPEX Mapping Parameters window PVC 2 8 SVC 2 8 TCP 2 9 IPEX Mapping Replication Window 2 15 IPEX Mapping Table Configuration Window 2 13 IPEX Mapping Table Configuration Window After Replication PVC to TCP Connection 2 16 TCP to PVC Connection 2 17 L LAN media 1 1 LAPB Link Access Procedure Balanced connection to TCP 1 7 description of 1 2 1 3 point to point connection 1 1 protocol 1 3 large data message 1 12 LCN logical channel number 1 7 Level 3 Packet Layer Protocol 1 3 Local TCP Port parameter 2 11 MAN metropolitan area network media 1 1 mapping 1 8 1 10 Mapping Type parameter 2 5 Index 2 Maximum Transmission Unit MTU 1 12 MCTI Multichannel T1 interface 1 1 message block 1 13 boundary 1 12 header 1 13 large 1 12 message based protocol 1 12 MTU Maximum Transmission Unit 1 12 netw
33. n Instructions Parameter Default Options Function Instructions MIB Object ID TCP Circuit Name None The name of this circuit When you add a TCP circuit the name is displayed in the Add Circuit window Identifies this TCP circuit for mapping purposes Enter the name of the appropriate TCP circuit If you do not know this name return to the main Configuration Manager window and click on the connector you are configuring to reopen the Add Circuit window TCP Header Type Short None Short Long Enables the Message Boundary Protocol This bit marks the boundary of TCP application data that is consistent with Gateway operation None means that there is no message header Message Boundary Protocol is off Short means that the message header contains a 2 byte length field Long means that the message header contains a 1 byte type a 1 byte version and a 2 byte length field Choose a header type 1 3 6 1 4 1 18 3 5 15 2 1 22 2 6 117378 A Rev A Configuring Mapping Parameters Enabling X 25 Gateway Complete the following steps to configure IPEX mapping parameters Site Manager Procedure You do this System responds 1 In the IPEX Mapping Add window click on OK The IPEX Mapping Parameters window opens Depending on your Source Connection Type Figure 2 2 Figure 2 3 or Figure 2 4 opens Configure the parameters appropriate to your connection type Click on He
34. ntal approvals Without limiting the foregoing Licensee on behalf of itself and its subsidiaries and affiliates agrees that it will not without first obtaining all export licenses and approvals required by the U S Government 1 export re export transfer or divert any such Software or technical data or any direct product thereof to any country to which such exports or re exports are restricted or embargoed under United States export control laws and regulations or to any national or resident of such restricted or embargoed countries or ii provide the Software or related technical data or information to any military end user or for any military end use including the design development or production of any chemical nuclear or biological weapons 9 General If any provision of this Agreement is held to be invalid or unenforceable by a court of competent jurisdiction the remainder of the provisions of this Agreement shall remain in full force and effect This Agreement will be governed by the laws of the state of California Should you have any questions concerning this Agreement contact Bay Networks Inc 4401 Great America Parkway P O Box 58185 Santa Clara California 95054 8185 LICENSEE ACKNOWLEDGES THAT LICENSEE HAS READ THIS AGREEMENT UNDERSTANDS IT AND AGREES TO BE BOUND BY ITS TERMS AND CONDITIONS LICENSEE FURTHER AGREES THAT THIS AGREEMENT IS THE ENTIRE AND EXCLUSIVE AGREEMENT BETWEEN BAY NETWORKS AND LICENSEE WHICH SU
35. on this value must be within the range of TCP ports reserved for Gateway service 12 304 to 16 399 Identifies the number of the first TCP port that will use the replicate configuration Enter the first TCP port number 2 18 117378 A Rev A Parameter Default Options Function Instructions Enabling X 25 Gateway TCP port increment None Any integer You can assign all of your replicates to the same port in which case you enter 0 for this parameter or you can assign each its own port by adding a value to each succeeding port number In the example given in Figure 2 6 each succeeding port is incremented by a value of 1 Instructs the router how to increment port numbers assigned to each of the replicate configurations Enter a value 117378 A Rev A 2 19 A adding an IPEX mapping entry 2 2 address called X 121 1 6 Bay Networks Press xii block message 1 13 boundary message 1 12 C called X 121 address 1 3 1 6 SVC with 1 6 SVC without 1 7 channel 1 7 circuits interface 1 6 configuration file preparing 2 1 replicating 2 12 Configuration Manager 1 1 configuring IPEX mapping parameters 2 7 congestion 1 3 1 5 connection automatic reestablishment after a fault occurs 1 8 from a LAPB terminal 1 7 from a TCP IP terminal 1 9 from an X 25 terminal 1 6 summary 1 11 copying a configuration 2 12 customer support programs xii 117378 A Rev A Index Technical So
36. ork topology TCP IP to LAPB 1 2 TCP IP to X 25 1 2 P Packet Layer Protocol See PLP parameters IPEX Destination Connection Type 2 12 Destination PVC LCN 2 12 Local TCP Port 2 11 Mapping Type 2 5 Remote IP Address 2 10 Remote TCP Port Number 2 11 Source Connection Type 2 4 Source PVC LCN 2 9 TCP Circuit Name 2 6 TCP Header Type 2 6 X 121 Called Address 2 10 permanent virtual circuit See PVC PLP Packet Layer Protocol 1 3 point to point connection 1 1 port TCP 1 4 2 11 protocol IP 1 3 message based X 25 1 12 TCE 1 3 TCP stack 1 11 unstructured stream TCP 1 12 X 25 Level 2 1 3 117378 A Rev A X 25 Level 3 1 3 X 25 stack 1 11 publications ordering xii PVC configuring for X 25 Gateway 1 3 description of Gateway connection 1 7 R Remote IP Address parameter 2 10 Remote TCP Port Number parameter 2 11 replicating a configuration 2 12 S Site Manager 1 1 socket 1 6 1 7 1 8 source circuit definition of 1 4 Source Connection Type parameter 2 4 Source PVC LCN parameter 2 9 stream protocol TCP 1 12 SVC configuring for X 25 Gateway 1 3 description of Gateway connection 1 6 with called X 121 called address 1 6 without called X 121 address 1 7 1 T1 interface 1 1 TCP description of Gateway connection 1 10 large data message 1 12 port number 2 11 protocol stack 1 11 socket 1 6 1 7 unstructured stream protocol 1 12 TCP Transmission Control P
37. ovision applies to all Software acquired for use within the European Community If Licensee uses the Software within a country in the European Community the Software Directive enacted by the Council of European Communities Directive dated 14 May 1991 will apply to the examination of the Software to facilitate interoperability Licensee agrees to notify Bay Networks of any such intended examination of the Software and may procure support and assistance from Bay Networks 7 Term and termination This license is effective until terminated however all of the restrictions with respect to Bay Networks copyright in the Software and user manuals will cease being effective at the date of expiration of the Bay Networks copyright those restrictions relating to use and disclosure of Bay Networks confidential information shall continue in effect Licensee may terminate this license at any time The license will automatically terminate if Licensee fails to comply with any of the terms and conditions of the license Upon termination for any reason Licensee will immediately destroy or return to Bay Networks the Software user manuals and all copies Bay Networks is not liable to Licensee for damages in any form solely by reason of the termination of this license 8 Export and Re export Licensee agrees not to export directly or indirectly the Software or related technical data or information without first obtaining any required export licenses or other governme
38. rotocol interface 1 4 port number 1 4 117378 A Rev A TCP Circuit Name parameter 2 6 TCP Header Type parameter 2 6 TCP IP to X 25 gateway 1 2 Technical Solutions Centers xiii terminal X 25 establishing connections from 1 6 token ring 1 1 translation stream 1 8 establishing TCP initiated 1 10 establishing X 25 initiated 1 5 X 25 to TCP 1 11 Transmission Control Protocol See TCP transmission unit maximum 1 12 V VC virtual circuit 1 1 W windows IPEX Mapping Add 2 3 IPEX Mapping Parameters PVC 2 8 SVC 2 8 TCP 2 9 IPEX Mapping Replication 2 15 IPEX Mapping Table Configuration 2 13 IPEX Mapping Table Configuration After Duplication TCP to PVC Connection 2 17 IPEX Mapping Table Configuration After Replication PVC to TCP Connection 2 16 X X 121 called address 1 3 1 6 1 7 X 121 Called Address parameter 2 10 X25 Gateway definition of 1 1 large data message 1 12 Index 3 Level 2 ee ers D 1 1 3
39. scriptions in Configuring X 25 Services First PVC LCN Number of PVC LCN Service VC Type Window Size Packet Size 8 Click on OK The IPEX Mapping Table Configuration window opens 9 Click on Add The IPEX Mapping Add window opens Figure 2 1 10 Set the following parameters Click on Help or see the parameter descriptions beginning on page 2 4 Source Connection Type Mapping Type TCP Circuit Name TCP Header Type 117378 A Rev A Configuring X 25 Gateway Services Cancel OK Values Help Source Connection Type PVC Mapping Type GATEWAY TCP Circuit Name MCT1 21 1 TCP Header Tupe Figure 2 1 IPEX Mapping Add Window for Source PVC Note This window is the same for PVC SVC and TCP source connections The Mapping Type is always Gateway Values for the other parameters are specific to your network Parameter Source Connection Type Default None Option PVC SVC TCP Function Specifies the type of connection at the sending end of the original message PVC and SVC specify an X 25 Level 3 connection either a permanent virtual circuit or a switched virtual circuit TCP is a Transmission Control Protocol connection Source connection types PVC and SVC send to destination connection type TCP Source connection type TCP sends to destination connection type PVC or SVC Instructions Select PVC to specify an X 25 connection to a permanent virtual cir
40. sed to establish a TCP connection to the destination You configure this parameter only when the source connection type is SVC Enter the IP address of the remote connection Use dotted decimal notation for example 1 1 1 1 Consult your network administrator for the correct value 1 3 6 1 4 1 18 3 5 15 2 1 12 2 10 117378 A Rev A Enabling X 25 Gateway Parameter Default Options Function Instructions MIB Object ID Remote TCP Port Number None The TCP port number at the remote connection a value between 12304 and 16399 Specifies the remote TCP port number used to establish a TCP connection to the destination The remote TCP port originates connections to the local TCP port You configure this parameter only when the source connection type is SVC Enter the TCP port number for the remote connection 1 3 6 1 4 1 18 3 5 15 2 1 13 Parameters for TCP Connections Parameter descriptions for TCP connections follow Parameter Default Options Function Instructions MIB Object ID Local TCP Port None The local TCP port number a value between 12304 and 16399 Specifies the TCP port in the local IPEX connection This port accepts inbound TCP connections from the remote TCP port You configure this parameter when the Source Connection Type is TCP Enter the TCP port number 1 3 6 1 4 18 3 5 15 2 1 5 117378 A Rev A Configuring X 25 Gateway Services Parameter Default Options
41. t correspond to the X 25 called address This correspondence is the mapping information that you must configure for X 25 to TCP conversion The mapping information consists of e The point of attachment that is the circuit interface on the Gateway system at which the SVC establishes the connection e The X 25 called address of the incoming connection e The associated remote TCP socket IP address and TCP port number that identifies the remote end of the TCP connection 1 6 117378 A Rev A X 25 Gateway Overview SVCs Without a Called X 121 Address When the X 25 SVC connection does not contain an X 121 called address in the incoming call request packet you specify the SVC service on that circuit to be a special SVC service interface by configuring e The circuit interface in X 25 Gateway at which the SVC establishes the connection The SVC service interface on that circuit which is special in that it must be set up as a data terminal equipment DTE interface instead of as a data circuit terminating equipment DCE interface e The associated remote TCP socket remote IP address and TCP port number that identifies the remote end of the TCP connection The router uses this information to form a translation session by accepting this connection and establishing an associated TCP connection Permanent Virtual Circuits PVCs For each permanent virtual circuit connection between the X 25 system and X 25 Gateway there
42. te message is contained within one or in several data segments When X 25 Gateway receives the X 25 user data and translates it to a TCP data segment the message boundary is lost To minimize changes in the existing host applications X 25 Gateway maintains the X 25 message boundary It structures the application information into message blocks before encapsulating it in TCP data segments Each message block contains a header and a data portion 117378 A Rev A X 25 Gateway Overview X 25 Gateway Message Block Options You can configure X 25 Gateway with the following message block options e No message block structure in any TCP segment X 25 Gateway translates each TCP data segment as a complete message e Message length specified The header portion of the message contains a 2 byte message length field The data portion holds the actual application information The length field indicates the total length of the application data portion in the message block Message version type and length specified in the header The header specifies the version of the message header format including a More flag bit The Type field specifies the message type DATA The data portion holds the actual application information The message block options that let you specify the message length allow TCP clients to determine message boundaries Depending on the size of the message block a TCP data segment can contain multiple message blocks
43. test version of Bay Networks Site Manager and router software For instructions refer to Upgrading Routers from Version 7 11 xx to Version 12 00 117378 A Rev A Configuring X 25 Gateway Services Conventions bold text italic text quotation marks screen text separator gt vertical line Indicates text that you need to enter command names and buttons in menu paths Example Enter wfsm amp Example Use the dinfo command Example ATM DXI gt Interfaces gt PVCs identifies the PVCs button in the window that appears when you select the Interfaces option from the ATM DXI menu Indicates variable values in command syntax descriptions new terms file and directory names and book titles Indicate the title of a chapter or section within a book Indicates data that appears on the screen Example Set Bay Networks Trap Monitor Filters Separates menu and option names in instructions and internal pin to pin wire connections Example Protocols gt AppleTalk identifies the AppleTalk option in the Protocols menu Example Pin 7 19 20 Indicates that you enter only one of the parts of the command The vertical line separates choices Do not type the vertical line when entering the command Example If the command syntax is show at routes nets you enter either show at routes or show at nets but not both 117378 A Rev A Acronyms CCITT DCE DDN DTE FDDI IP IPEX
44. ttempts to establish an outgoing connection on the destination circuit In Figure 1 2 the source circuit is the one with the X 25 connection Protocol Translation Figure 1 2 shows the sequence of establishing the translation session when the connection request comes from the X 25 terminal 1 4 117378 A Rev A X 25 terminal poU Step 1 connection requested X 25 terminal L p X 25 request pending Step 2 X 25 terminal C X 25 reguest pending Step 3 X 25 terminal Step 4 O X 25 request accepted Figure 1 2 X 25 Gateway Overview X 25 gateway router TCP IP mcm host el X 25 gateway router TCP IP host Ei TCP connection X 25 attempt gateway router TCP IP host 3 zZ TCP connection X 25 accepted gateway router TCP IP ca host Ee gt m TCP connection established X250023A How X 25 Gateway Establishes a Session X 25 Initiated If the router detects congestion on the receiving side of the network it controls the data flow by queuing the requests on the sending side until the congestion lifts or the connection terminates 117378 A Rev A 1 5 Configuring X 25 Gateway Services Establishing Connections from the X 25 Equipment Either the X 25 equipment or the TCP IP based system can
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