Overview of IBM Networking The IBM networking technologies described in this publication can be categorized as network-related or host-related technologies.
Overview of IBM Networking RSRB Note All commands supported on the Cisco 7500 series routers are also supported on the Cisco 7000 series routers. RSRB In contrast to Source-Route Bridging (SRB), which involves bridging between Token Ring media only, RSRB is Cisco’s first technique for connecting Token Ring networks over non-Token Ring network segments. (DLSw+ is Cisco’s strategic method for providing this function.
Overview of IBM Networking RSRB Configuration Considerations Use IP encapsulation only over a TCP connection within complex meshed networks to support connections between peers that are separated by multiple hops and can potentially use multiple paths, and where performance is not an issue. Use direct encapsulation in point-to-point connections. In a point-to-point configuration, using TCP adds unnecessary processing overhead.
Overview of IBM Networking DLSw+ Note As previously stated, local acknowledgment for LLC2 is meant only for extreme cases in which communication is not possible otherwise. Because the router must maintain a full LLC2 session, the number of simultaneous sessions it can support before performance degrades depends on the mix of other protocols and their loads. The routers at each end of the LLC2 session execute the full LLC2 protocol, which can result in some overhead.
Overview of IBM Networking DLSw+ This section contains a brief overview of DLSw+ which is described in the following topics: • DLSw Standard, page 207 • DLSw Version 2 Standard, page 207 • DLSw+ Features, page 208 DLSw Standard The DLSw standard, documented in RFC 1795, defines the switch-to-switch protocol between DLSw routers. The standard also defines a mechanism to terminate data-link control connections locally and multiplex the traffic from the data-link control connections to a TCP connection.
Overview of IBM Networking DLSw+ IP Multicast Multicast service avoids duplication and excessive bandwidth of broadcast traffic because it replicates and propagates messages to its multicast members only as necessary.
Overview of IBM Networking DLSw+ This section contains information on the following topics related to DLSw+ features: • Local Acknowledgment, page 209 • Notes on Using LLC2 Local Acknowledgment, page 211 • DLSw+ Support for Other SNA Features, page 212 DLSw+ is fully compatible with any vendor’s RFC 1795 implementation and the following features are available when both peers are using DLSw+: • Peer groups and border peers • Backup peers • Promiscuous and on-demand peers • Explorer firewalls an
Overview of IBM Networking DLSw+ Figure 86 illustrates an LLC2 session in which a 37x5 on a LAN segment communicates with a 3x74 on a different LAN segment separated via a wide-area backbone network. Frames are transported between Router A and Router B by means of DLSw+. However, the LLC2 session between the 37x5 and the 3x74 is still end-to-end; that is, every frame generated by the 37x5 traverses the backbone network to the 3x74, and the 3x74, on receipt of the frame, acknowledges it.
Overview of IBM Networking DLSw+ 3x74 operates as if the acknowledgments it receives are from the 37x5. Router B looks like the 3x74 to 37x5. Because the frames do not have to travel the WAN backbone networks to be acknowledged, but are locally acknowledged by routers, the end machines do not time out, resulting in no loss of sessions.
Overview of IBM Networking DLSw+ If you are using NetBIOS applications, note that there are two NetBIOS timers—one at the link level and one at the next higher level. Local acknowledgment for LLC2 is designed to solve link timeouts only. If you are experiencing NetBIOS session timeouts, you have two options: Note • Experiment with increasing your NetBIOS timers and decreasing your maximum NetBIOS frame size. • Avoid using NetBIOS applications on slow serial lines.
Overview of IBM Networking STUN and BSTUN Figure 88 VDLC Interaction with Higher-Layer Protocols DLSw+ SNASw Data-link users CLSI Ethernet VDLC Data link controls 28665 Token Ring The higher-layer protocols make no distinction between the VDLC and any other data-link control, but they do identify the VDLC as a destination. In the example shown in , SNASw has two ports: a physical port for Token Ring and a logical (virtual) port for the VDLC.
Overview of IBM Networking STUN and BSTUN Figure 89 Comparison of STUN in Passthrough Mode and Local Acknowledgment Mode 37x5 IBM 1 3x74 IBM1 WAN SDLC session SNA session TCP session 3x74 IBM 2 WAN SDLC session SDLC session SNA session Note S2839 37x5 IBM 1 To enable STUN local acknowledgment, you first enable the routers for STUN and configure them to appear on the network as primary or secondary SDLC nodes. TCP/IP encapsulation must be enabled.
Overview of IBM Networking STUN and BSTUN • Allows networks with IBM mainframes and communications controllers to share data using Cisco routers and existing network links. As an SDLC function, STUN fully supports the IBM SNA and allows IBM SDLC frames to be transmitted across the network media and shared serial links. illustrates a typical network configuration without STUN and the same network configured with STUN.
Overview of IBM Networking STUN and BSTUN Figure 90 IBM Network Configuration without STUN and with STUN Workstation IBM mainframe Ethernet 37x5 Local site Without STUN T1 serial link 3x74 Remote site Ethernet IBM 3x78 terminals Workstation IBM mainframe 37x5 Workstation Local site Ethernet With STUN T1 serial link Remote site Ethernet Workstation IBM 3x78 terminals Cisco IOS Bridging and IBM Networking Configuration Guide BC-216 S2075 3x74
Overview of IBM Networking LLC2 and SDLC Parameters BSTUN Networks The Bisync feature enables your Cisco 2500, 3600, 4000, 4500, 4700, and 7200 series router to support devices that use the Bisync data-link protocol. This protocol enables enterprises to transport Bisync traffic over the same network that supports their SNA and multiprotocol traffic, eliminating the need for separate Bisync facilities. At the access router, traffic from the attached Bisync device is encapsulated in IP.
Overview of IBM Networking LLC2 and SDLC Parameters LLC2 and SDLC package data in frames. LLC2 and SDLC stations require acknowledgments from receiving stations after a set amount of frames have been sent before sending further data. The tasks described in this chapter modify default settings regarding the control field of the data frames.
Overview of IBM Networking IBM Network Media Translation Cisco’s Implementation of SDLC Cisco’s SDLC implementation supports the following features: • Frame Relay Access Support (FRAS) With FRAS, a router functions as a Frame Relay Access Device (FRAD) for SDLC, Token Ring, and Ethernet-attached devices over a Frame Relay Boundary Network Node (BNN) link. Frame Relay access support is described in the chapter “Configuring SNA Frame Relay Access Support.
Overview of IBM Networking IBM Network Media Translation Figure 91 SNA Data Link Layer Support SNA Data link layer SDLC SDLLC LLC LNX QLLC X.25 S3028 Upper layers SDLLC Media Translation Features The SDLLC feature allows a PU 4, PU 2.
Overview of IBM Networking IBM Network Media Translation As part of its virtual telecommunications access method (VTAM) configuration, the IBM node on the Token Ring has knowledge of the SDLLC VTRA of the serial device with which it communicates. The SDLC VTRA and the SDLLC virtual ring number are a part of the SDLLC configuration for the router’s serial interface.
Overview of IBM Networking IBM Network Media Translation QLLC Conversion Qualified Logical Link Control (QLLC) is a data link protocol defined by IBM that allows SNA data to be transported across X.25 networks. (Although IBM has defined other protocols for transporting SNA traffic over an X.25 network, QLLC is the most widely used.) Figure 92 illustrates how QLLC conversion provides data link layer support for SNA communication.
Overview of IBM Networking IBM Network Media Translation QLLC Conversion Running on a Router with an Intermediate IP Network X.25/QLLC session TCP session Running RSRB Running QLLC X.25 network LLC2 session Token Ring IP network Router A S3031 Figure 95 Router B Cisco’s Implementation of QLLC Conversion SNA uses QLLC and X.25 as link layer protocols to provide a reliable connection. QLLC itself processes QLLC control packets.
Overview of IBM Networking IBM Network Media Translation As Figure 97 shows, a router need not directly connect the two IBM end nodes; instead, some type of backbone WAN can connect them. Here, RSRB transports packets between Router A and Router B, while Router B performs all conversion between the LLC2 and X.25 protocols. Only the router attached to the serial line (Router B) needs to be configured for QLLC conversion. Both Router A and Router B are configured for normal RSRB.
Overview of IBM Networking IBM Network Media Translation circuits (PVCs) are available, but the favored use is SVC. While the router maintains a permanent connection to the X.25 network, a remote device can use each SVC for some bounded period of time and then relinquish it for use by another device. Using a PVC is very much like using a leased line. Table 3 shows how the QLLC commands correspond to the SDLLC commands.
Overview of IBM Networking SNA FRAS SNA FRAS Using Frame Relay Access Support (FRAS), the Cisco IOS software allows branch SNA devices to connect directly to a central site front-end processor over a Frame Relay network. FRAS converts LAN or Synchronous Data-Link Control (SDLC) protocols to a Frame Relay format understood by the Network Control Program (NCP) that runs in an FEP. The Cisco IOS software and the NCP support two frame formats: • RFC 1490 routed format for LLC2, specified in the FRF.
Overview of IBM Networking SNA FRAS Figure 99 SNA BNN Support for Frame Relay Frame Relay Token Ring S3218 SDLC NCP The frame format that communicates across the Frame Relay BNN link is defined in RFC 1490 for routed SNA traffic. From the perspective of the SNA host (for example an NCP or AS/400), the Frame Relay connection is defined as a switched resource similar to a Token Ring BNN link.
Overview of IBM Networking NCIA Figure 100 RFC 1490 Bridged Frame Format Q.922 Address Control 0x03 pad 0x00 NLPID SNAP 0x80 OUI 00x0 OUI 0x80-C2 (bridged) PID 0x00-09 pad 0x00 Frame Control Destination/Source MAC (12 bytes) DSAP SSAP Control PCS H7115 SNA Data Because it includes the MAC header information in every frame, BAN supports multiple SNA devices sharing a single permanent virtual circuit without requiring SAP multiplexing.
Overview of IBM Networking NCIA NCIA I Cisco’s NCIA server feature implements RFC 2114, Data Link Switch Client Access Protocol. Using Cisco’s RSRB technology, NCIA I encapsulates the Token Ring traffic inside IP datagrams passed over a TCP connection between a router and a client. A virtual ring is created to allow the router to interconnect any client.
Overview of IBM Networking NCIA Figure 101 NCIA Server Client/Server Model DLSw+ SNASw DLSw local switch DSPU SNA LLC2 RSRB NCIA Client Token Ring TCP/IP TCP/IP S4696 Ethernet NCIA Server NDLC NCIA Data Link Control (NDLC) is the protocol used between clients and servers. NDLC serves two purposes: • Establishes the peer connection • Establishes the circuit between the client and the server The peer session must be established before an end-to-end circuit can be set up.
Overview of IBM Networking NCIA Advantages of the Client/Server Model The client/server model used in the NCIA Server feature extends the scalability of NCIA. In addition, it provides support for both the installed base of RSRB routers and the growing number of DLSw+ routers. Extended Scalability The client/server model minimizes the number of central site RSRB or DLSw+ peer connections required to support a large network of NCIA clients (see Figure 102).
Overview of IBM Networking ALPS Figure 103 NCIA Server Provides Independence from the Upstream Network Implementation Client Workstation Token Ring DLSw+ NCIA Server RSRB/DLSw+ IP Backbone Token Ring Cisco Mainframe with FEP RSRB Computing Center S4706 NCIA Server Router Peers ALPS The Airline Product Set (ALPS) is a tunneling mechanism that transports airline protocol data across a TCP/IP network to a mainframe.
Overview of IBM Networking DSPU and SNA Service Point Figure 104 ALPS Architecture Remote router ASCUs running ALC or UTS 25065 Mainframe with airline reservation system Network management system Remote router ASCUs running ALC or UTS Cisco’s ALPS feature provides an end-to-end solution for airlines and central reservation systems.The ALPS feature is integrated in the Cisco IOS software and allows airlines to replace their existing hardware and software with Cisco routers.
Overview of IBM Networking DSPU and SNA Service Point Figure 105 Router Acting as a DSPU Concentrator LU LU PU 2 + 3 LUs RSRB PU 2 Mainframe with 1 PU and 8 LUs defined PU 5 DSPU concentrator supporting 4 PUs and 8 LUs Token Ring PU 2 + 1 LU PU 2 + 2 LUs S3223 Token Ring Typically, a router establishes one or more upstream connections with one or more hosts and many downstream connections with PU type 2 devices.
Overview of IBM Networking SNA Switching Services SNA Switching Services Note SNA Switching Services functionality supersedes all functionality previously available in the APPN feature in the Cisco IOS software. SNASw configuration will not accept the previous APPN configuration commands. Previous APPN users should use this chapter to configure APPN functionality using the new SNASw commands. SNASw provides an easier way to design and implement networks with SNA routing requirements.
Overview of IBM Networking Benefits of SNASw Scalable APPN Networks With the Branch Extender (BEX) function, the number of network nodes and the amount of broadcast traffic are reduced. IP Infrastructure Support Limiting SNASw routers to the data center and using the BEX function eliminates SNA broadcasts from the IP network. With Enterprise Extender (EE), SNA traffic is routed using the IP routing infrastructure while maintaining end-to-end SNA services.
Overview of IBM Networking HPR Capable SNA Routing Services HPR Capable SNA Routing Services SNASw provides the following SNA routing functions: • Routes SNA sessions between clients and target SNA data hosts. • Supports full SNA class of service (COS) features. • Controls SNA traffic in a multiprotocol environment in conjunction with other Cisco IOS quality of service (QOS) features.
Overview of IBM Networking Enterprise Extender (HPR/IP) Figure 107 BX Functionality Downstream devices CS/390 EN Emulated EN Emulated NN SNASw Cisco CIP PU 2.0 EN CS/390 NN 26186 LEN Enterprise Extender (HPR/IP) SNASw also supports the EE function. EE offers SNA HPR support directly over IP networks. EE also uses connectionless User Datagram Protocol (UDP) transport.
Overview of IBM Networking Usability Features Usability Features SNASw contains the following usability features designed to make SNA networks easier to design and maintain: • Dynamic CP Name Generation Support, page 239 • Dynamic SNA BTU Size, page 239 • DLUR Connect-Out, page 239 • Responsive Mode Adaptive Rate-Based Flow Control, page 240 • User-Settable Port Limits, page 240 Dynamic CP Name Generation Support When scaling the SNASw function to hundreds or thousands of nodes, many network admi
Overview of IBM Networking Management Enhancements Responsive Mode Adaptive Rate-Based Flow Control Early HPR implementations failed to perform well in environments subject to packet loss (for example, Frame Relay, IP transport) and performed poorly when combined with other protocols in multiprotocol networks. SNASw implements the second-generation HPR flow control architecture, called Responsive Mode Adaptive Rate-Based (ARB) architecture.
Overview of IBM Networking LAN and IP-Focused Connection Types Trap MIB Support for Advanced Network Management Awareness SNASw supports the APPN Trap MIB, which proactively sends traps with information about changes in SNA resource status. This implementation reduces the frequency of SNMP polling necessary to manage SNA devices in the network.
Overview of IBM Networking Cisco Transaction Connection Connection to Channel Interface Processor and Channel Port Adapter Virtual Token Ring and SRB can be used to connect SNASw to the Channel Interface Processor (CIP) or Channel Port Adapter (CPA) in routers that support those interfaces. Virtual Data-Link Control SNASw uses Virtual Data-Link Control (VDLC) to connect to DLSw+ transport and local switching technologies.
Overview of IBM Networking Cisco Transaction Connection • CTRC supports the ability to configure routes for CICS transaction. Each transaction can be routed to a specific CICS region.
Overview of IBM Networking Cisco Transaction Connection Figure 109 Cisco Router Configured with the CTRC Feature for CICS Communications CICS transaction monitor CICS client TCP/IP TCP/IP SNA TCP/IP SNA SNA APPC (LU 6.2) 26062 CTRC CTRC and DB2 CTRC enables Cisco routers to implement IBM’s DRDA over TCP/IP.
Overview of IBM Networking CMCC Adapter Hardware For a TCP/IP host connection, the router with CTRC routes the DRDA packets over TCP/IP without protocol changes. To use this TCP/IP passthrough feature of CTRC, the host database version must support direct TCP/IP access. Figure 111 illustrates such a configuration.
Overview of IBM Networking CMCC Adapter Hardware Figure 112 Cisco Mainframe Channel Connection Adapters 7500 with CIP Channel 1/0 ESCON IP SNA APPN HPR TN3270 Channel 1/1 Parallel channel (Bus-and-Tag) LPAR1 LPAR2 APPN HPR TCP/IP SNA ESCON or Parallel Channel 1/0 13337 7200 with CPA Channel Interface Processor The CIP for the Cisco 7000 with RSP7000 and Cisco 7500 series routers is designed for high-end network environments that demand high-performance, high-port density, and high-capacity sol
Overview of IBM Networking CMCC Adapter Hardware The Cisco 7200 series router supports online insertion and removal (OIR), which allows you to install or remove port adapters while the system is operating. Note In this chapter, references to Channel Port Adapter (CPA) correspond to both the ECPA and the PCPA. Refer to the Cisco 7200 Series Port Adapter Hardware Configuration Guidelines publication for more details.
Overview of IBM Networking CMCC Adapter Features for TCP/IP Environments Supported Environments The Cisco IOS software supports the following environments and features on the CMCC adapters: • TCP/IP Environments—CLAW, TCP/IP offload, IP host backup, CMPC+, and TN3270 server features • SNA and APPN Environments—CSNA, CMPC, and TN3270 server features CMCC Adapter Features for TCP/IP Environments The Cisco IOS software supports the following features for CMCC adapters in TCP/IP environments: • Common Lin
Overview of IBM Networking CMCC Adapter Features for TCP/IP Environments IP Host Backup You can connect multiple mainframes to a single CMCC adapter using an ESCON director. Often, these mainframes run using the ESCON Multiple Image Facility (EMIF), which permits the physical machine to be divided into multiple logical partitions (LPARs). By defining an unused partition on another mainframe, a user can move the operating system from a failed mainframe or mainframe partition to the unused partition.
Overview of IBM Networking CMCC Adapter Features for SNA Environments CMCC Adapter Features for SNA Environments The Cisco IOS software supports the following features for CMCC adapters in SNA environments: • Cisco SNA, page 250 • Cisco Multipath Channel, page 251 • TN3270 Server, page 251 Cisco SNA The CSNA feature provides support for SNA protocols to the IBM mainframe from Cisco 7500, Cisco 7200, and Cisco 7000 with RSP7000 series routers, using CMCC adapters (over both ESCON and parallel interfac
Overview of IBM Networking CMCC Adapter Features for SNA Environments Cisco Multipath Channel CMPC is Cisco System’s implementation of IBM’s MultiPath Channel (MPC) feature on Cisco 7500, Cisco 7200, and Cisco 7000 with RSP7000 series routers. CMPC allows VTAM to establish Advanced-Peer-to-Peer Networking (APPN) connections using both High Performance Routing (HPR) and Intermediate Session Routing (ISR) through channel-attached router platforms.
Overview of IBM Networking CMCC Adapter Features for SNA Environments The TN3270 server feature offers an attractive solution when the following conditions need to be supported in an SNA environment: • Maintaining an IP backbone while providing support for SNA 3270-type clients. • Offloading mainframe CPU cycles when using a TN3270 host TCP/IP stack with a TN3270 server. • Providing support for high session density or high transactions per second.
Overview of IBM Networking CMCC Adapter Features for SNA Environments Note To enable the TN3270 server feature, you must have a CMCC adapter installed in a Cisco 7000 with RSP7000, Cisco 7500 series router, or a Cisco 7200 router. The TN3270 server is very different from the TN3270 terminal emulation access feature described in the “Configuring Dial-In Terminal Services” chapter of the Cisco IOS Dial Services Configuration Guide:Terminal Services.
Overview of IBM Networking CMCC Adapter Features for SNA Environments Cisco IOS Bridging and IBM Networking Configuration Guide BC-254