Whitepaper on Migrating X.25 over PSI to X.
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Contents 1 2 3 4 5 6 7 Introduction...............................................................................................4 X.25 Overview...........................................................................................5 X.25 over PSI.............................................................................................6 TCP/IP Overview........................................................................................7 X.25 over TCP...............................................
1 Introduction X.25 is the International Telecommunication Union-Telecommunication Standardization Sector (ITU-T) Protocol standard for WAN communication. X.25 defines how connections between user devices and Network devices are established and maintained in a packet- switched data network. With Ethernet evolving as the preferred network backbone for all environments, X.25 customers are seeking solutions to run X.25 applications on Ethernet interface. X.
2 X.25 Overview The HP-UX X.25 link solution provides the hardware and software components that enable HP 9000 systems and Integrity systems to communicate with other HP and non-HP systems over X.25 packet switching networks. The X.25 link implements the CCITT X.25 Recommendations and includes the components necessary to connect HP 9000 systems and Integrity systems to a public or private packet switching network or to another system in a back-to-back configuration that conforms to the CCITT X.
3 X.25 over PSI In accordance with CCITT X.25 Recommendations, three layers of protocol (Layer 1, Layer 2 and Layer 3) are functional when X.25 is used over PSI cards. Figure 2 shows the three protocol layers in X.25 over PSI. Figure 2 Three layers of protocol in X.25 over PSI 6 X.
4 TCP/IP Overview The primary purpose of the TCP is to provide reliable, securable logical circuit or connection service between pairs of processes. To provide this service on top of a less reliable communication system, the connection oriented TCP protocol has built-in features like Reliability, Flow Control, Multiplexing, Precedence and Security.
5 X.25 over TCP X.25 over TCP (XOT) is based on RFC 1613 (Cisco Systems X.25 over TCP (XOT)). Configuring XOT allows X.25 layer 3 to connect to TCP/IP stack instead of LAP-B and provides X.25 functionality on top of a TCP/IP infrastructure. 8 X.
6 Relationship between X.25 and TCP/IP X.25 requires that the layer below it provides message semantics, in particular in the boundary between packets. To provide this, a small (4-byte) XOT header is added between TCP and X.25. XOT is intended to be insensitive to the DTE/DCE role of the local interfaces at either end of an XOT TCP connection. A separate TCP connection MUST be used for each X.25 virtual circuit. All connections MUST be made to TCP port number 1998.
7 Features of XOT • X.25 over TCP(XOT) allows HP Integrity customers to deploy X.25 applications over a TCP/IP network (without the need of a dedicated X.25 HW card). • Supports Internet Services for HP Integrity/HP 9000-to-HP Integrity/HP 9000 or HP Integrity/HP 9000-to-non-HP computer communication. • Implementation of the X.25 over TCP (XOT) protocol as specified in RFC1613.
8 Benefits of XOT against PSI Following are the advantages of using XOT instead of X.25 over PSI card: Lower hardware cost • Ethernet cards cost less compared to PSI cards. Moreover, the extensive use and large demand for Ethernet cards are expected to lower the cost of Ethernet cards. Lower operational cost • The administration, management, and maintenance costs involved in implementing XOT systems with Ethernet cards are significantly lesser than the costs involved in implementing X.25 over PSI.
9 Migrating X.25 over PSI to XOT XOT is supported on Ethernet cards. This section discusses how to migrate X.25 over PSI to XOT, using Ethernet cards. The migration of X.25 over PSI to XOT involves the following: • Hardware migration • Configuration migration • Application migration Hardware Migration The following hardware elements, which are a part of the X.25 network, are impacted in the migration process: • Cards The HP-UX X.
Figure 3 Network configuration with X.
Figure 4 Network configuration with X.25 over TCP/IP Configuration Migration The XOT functionality on HP-UX 11iv3 is delivered along with the September 2011 (AR1109) release of X.25 product. To configure XOT functionality, the following configuration files must be edited or manually added. • Generic X.
Table 2 Parameters for XOT Field Format Value name xot An XOT interface name NOTE: format It must be in this prescribed local_tcpip_address Dotted decimal notation A valid IP Address configured on the system flowcontrol on Flow control must be ON for a SVC neg_inpacketsize A valid packet size between 128 and Incoming packet size for SVC. 4096 octets Recommended X.25 packet size for XOT is 1024 octets.
Example 1 shows a sample X.25 configuration with XOT specific parameters # # Likely runstring: x25init -c /etc/x25/x25init_xot_def -X /etc/x25/x121_to_ip_map X.121 55555 # X.121 address X.121_packet 55555 # use a null (i.e. length 0) packet # address (TransPac addressing) name xot0 # interface name for Level 3 access # It MUST be of the format xot# # where "instance number" can take a value from 0 to 9 # # XOT Specific Parameters # local_tcpip_address 10.0.0.
Example 2 Sample XOT specific configuration file # X.25 to IP Map File # SVC Routing Information, as per RFC 1613 # #Destination X.21 Destination # Address IP Address 55555 10.0.0.3 11111 10.0.0.4 # # PVC Routing Information as per RFC 1613 # Local(LCN),Remote(LCN),LocalInterfacename,RemoteInterfacename,Remoteip pvcroute 1 4 xot0 xot0 10.0.0.3 #PVC channel 1 mapped to channel 4 pvcroute 2 3 xot0 xot0 10.0.0.4 #PVC channel 2 mapped to channel 3 pvcroute 3 2 xot0 xot0 10.0.0.
Example 3 Configuration on Host A before Migration: X.25 interface: hosta_0p1 X.25 Configuration File: /etc/x25/x25config_0p1 # X.25 Initialization File Created: Tue Apr 3 18:32:47 2012 # # # Global Parameters # x.121 11111 x.
Example 4 Configuration on Host B before Migration: X.25 interface: hostb_0p2 X.25 Configuration File: /etc/x25/x25config_0p2 # X.25 Initialization File Created: Tue Apr 3 18:36:47 2012 # # # Global Parameters # x.121 22222 x.
Figure 6 Topology after Migration- Two hosts are now connected across a TCP/IP Network through XOT over a SVC 20 Migrating X.
Example 5 Configuration on Host A after migration: X.25 interface: xot0 Generic XOT Configuration File: /etc/x25/x25init_xot_def # Likely runstring: x25init -c /etc/x25/x25init_xot_def –X /etc/x25/x121_to_ip_map X.121 11111 # X.121 address X.121_packet 11111 # use a null (i.e.
Example 7 Configuration on Host B after migration: X.25 interface: xot0 Generic XOT Configuration File: /etc/x25/x25init_xot_def # Likely runstring: x25init -c /etc/x25/x25init_xot_def –X /etc/x25/x121_to_ip_map X.121 22222 # X.121 address X.121_packet 22222 # use a null (i.e.
Scenario # 2: Migrating a PVC over X.25/LAPB (PSI) to a PVC over XOT Figure 7 Initial X.25 Topology: Two hosts are connected across a X.25 switch through X.25/LAPB Protocol over a PVC In the above topology, assume that the PVC Table Entries in the X.
Example 9 Configuration on Host A before Migration: X.25 interface: hosta_0p1 X.25 Configuration File: /etc/x25/x25config_0p1 # X.25 Initialization File Created: Tue Apr 3 18:54:56 2012 # # # Global Parameters # x.121 11111 x.
Example 10 Configuration on Host B before Migration: X.25 interface: hostb_0p2 X.25 Configuration File: /etc/x25/x25config_0p2 # X.25 Initialization File Created: Tue Apr 3 18:58:56 2012 # # # Global Parameters # x.121 22222 x.
Figure 8 Topology after Migration- Two hosts are now connected across a TCP/IP Network through XOT over a PVC 26 Migrating X.
Example 11 Configuration on Host A after Migration: X.25 interface: xot0 Generic XOT Configuration File: /etc/x25/x25init_xot_def Likely runstring: x25init -c /etc/x25/x25init_xot_def –X /etc/x25/x121_to_ip_map X.121 11111 # X.121 address X.121_packet 11111 # use a null (i.e.
Example 13 Configuration on Host B after Migration: X.25 interface: xot0 Generic XOT Configuration File: /etc/x25/x25init_xot_def # Likely runstring: x25init -c /etc/x25/x25init_xot_def –X /etc/x25/x121_to_ip_map X.121 22222 # X.121 address X.121_packet 22222 # use a null (i.e.
Scenario # 3: Connectivity between a X.25/LAPB interface and a XOT interface over a SVC Figure 9 Connectivity between X.
Example 15 Configuration on Host A: X.25 interface: hosta_0p1 X.25 Configuration File: /etc/x25/x25config_0p1 # X.25 Initialization File Created: Tue Apr 3 18:42:47 2012 # # # Global Parameters # x.121 11111 x.
Example 16 Configuration on Host B: X.25 interface: xot0 Generic XOT Configuration File: /etc/x25/x25init_xot_def # Likely runstring: x25init -c /etc/x25/x25init_xot_def –X /etc/x25/x121_to_ip_map X.121 22222 # X.121 address X.121_packet 22222 # use a null (i.e.
Example 17 XOT Specific Configuration File for Host B: /etc/x25/x121_to_ip_map # # X.25 to IP Map File for SVCs, as per RFC 1613 # #Destination X.21 Destination # Address IP Address 11111 10.0.0.1 22222 10.0.0.2 Configuration on the X.25/LAPB to XOT Router: This was verified with Cisco 2851 router, and the following X.25 routing table entries would have to be added. Cisco2851#configure terminal Cisco2851(config)# x25 route 11111 interface Serial 0/0/0 Cisco2851(config)# x25 route 22222 xot 10.0.0.
Scenario # 4: Connectivity between a X.25/LAPB interface and a XOT interface over a PVC Figure 10 Connectivity between X.25/LAPB interface and XOT over a PVC In the above topology, assume that the following PVC mapping needs to be used for the X.
Example 18 Configuration on Host A: X.25 interface: hosta_0p1 X.25 Configuration File: /etc/x25/x25config_0p1 # X.25 Initialization File Created: Tue Apr 3 19:04:56 2012 # # # Global Parameters # x.121 11111 x.
Example 19 Configuration on Host B: X.25 interface: xot0 # Likely runstring: x25init -c /etc/x25/x25init_xot_def –X /etc/x25/x121_to_ip_map X.121 22222 # X.121 address X.121_packet 22222 # use a null (i.e. length 0) packet # address (TransPac addressing) name xot0 # interface name for Level 3 access # It MUST be of the format xot # where "instance number" can take a value from 0 to 9 # # XOT Specific Parameters # local_tcpip_address 10.0.0.
Example 20 Configuration on Host B: X.25 interface: /etc/x25/x121_to_ip_map XOT Specific Configuration File: # # X.25 to IP Map File for SVCs, as per RFC 1613 # #Destination X.21 Destination # Address IP Address # None # PVC Routing Information, as per RFC 1613 # Local(LCN), Remote(LCN), LocalInterfacename, RemoteInterfacename,Remoteip pvcroute 1 1 xot0 Serial0/0/0 10.0.0.1 #PVC channel pvcroute 2 2 xot0 Serial0/0/0 10.0.0.1 #PVC channel pvcroute 3 3 xot0 Serial0/0/0 10.0.0.
Application Migration After the XOT interface is configured, the X.25 application uses the XOT interface to communicate with the peer X.25 systems (an XOT or an XOL or a PSI port.) The migration of X.25 from PSI to XOT is seamless. The X.25 applications require minimal or no changes after migration to XOT. The recommended packet size for XOT is 1024 bytes in Layer 3. XOT interfaces should always have interface names in the format xot.
10 Performance Performance benchmarking experiments have shown high throughput in case of X.25 over TCP as compared to X.25 over PSI.
11 Conclusion X.25 over TCP (XOT) allows HP Integrity customers to deploy X.25 applications over a TCP/IP network. This provides flexibility of running X.25 application on multiple hardware and software platforms. The consolidation of X.25 traffic onto a TCP/IP infrastructure reduces network costs while maintaining mission-critical X.25 support.
12 Related Documentation X.25 Documentation Section:http://www.hp.com/products1/serverconnectivity/adapters/x25.html? jumpid=reg_r1002_usen#orde X.25 Product Download Page: https://h20392.www2.hp.com/portal/swdepot/ displayInstallInfo.
