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TCP/IP Tutorial and Technical Overview

5.19 The IBM Hubs Family

Basically a hub is a wiring concentrator which connects the participating LAN workstations in a star-wired cabling system. Therefore a hub is mostly located in the wiring closet or near the workgroups. Today the term hub is used to describe multiprotocol devices offering sophisticated network management features and great flexibility for configuration.

One of the trends in networking is the move to centralize network functions in the wiring closet. This goes along with the trend toward collapsed backbones. A collapsed backbone uses the intelligent hub as the network backbone rather than using a segment of cable. Thus the backbone of the network is collapsed into the intelligent hub. This allows the network administrator to consolidate many network functions into a fault tolerant intelligent hub.

Hubs have been used in networks for wiring concentration for many years. Early hubs were passive devices that only provided for network connection such as the 8228. New hubs are becoming more sophisticated and they can do much more than act as wiring concentrators.

The following network functions can be consolidated in the intelligent hub:

IBM offers a large variety of hub products to build a secure, reliable and manageable LAN. Hubs can be divided into two major groups: the first group, which supports only one specific LAN protocol token-ring or FDDI (workgroup hubs) for example, and the second which supports multiple LAN protocols in a single box (intelligent hubs). In this section you get a brief description of the different available hubs and the major information from a TCP/IP point of view.

5.19.1 IBM 8230 Token-Ring Controlled Access Unit

The IBM 8230 is an intelligent token-ring network wiring concentrator, providing enhanced levels of control and reliability over passive token-ring network wiring concentrators, such as the IBM 8228.

The 8230 is a rack mountable device that:

For further information please refer to IBM 8230 Model 3 Planning Guide.

5.19.2 IBM 8222 Workgroup Hub

The IBM 8222 offers low-cost attachment for six 10Base-T nodes and has no in- or out-of-band network management. One of the six ports can be used to cascade to another 10BaseT concentrator when expansion is needed. Its suitable environment could be in small offices, using either permanently installed UTP or short lengths of UTP between devices that are in close proximity to one another. However, the modular expandability of Ethernet and relatively easy connection to the earlier bus topologies allow the IBM 8222 to be used as part of larger, even establishment-wide, LANs.

For further information please refer to IBM 6-Port 10Base-T Workgroup Hub Installation & Planning Guide.

5.19.3 IBM 8224 Ethernet Stackable Hub

The 8224 is IBM's newest Ethernet/802.3 hub. It provides low cost connectivity for 10Base-T networks. It can be managed through SNMP and it can connect to existing 10Base-5, 10Base-2, 10Base-T, and fiber networks.

The 8224 is a stackable, SNMP manageable Ethernet hub for 10Base-T networks. The following is a list of 8224 features:

For further information please refer to IBM 8224 Ethernet Stackable Hub Installation and User' Guide.

5.19.4 IBM 8244 FDDI Workgroup Concentrator

The IBM 8244 Fiber Distributed Data Interface (FDDI) Workgroup Concentrator is the primary attachment to the FDDI dual ring for attaching workstations to the backbone. The 8244 FDDI concentrator allows attaching up to 12 devices to a 100 Mbps network. These devices may be connected via:

The 8244 can provide connection for FDDI devices that are based on the ANSI and ISO standards. The 8244 will operate with management entities that support the ANSI Station Management (SMT) 7.3 frame-based protocols.

Concentrator management is made possible via the imbedded FDDI SNMP agent. This agent will maintain the concentrator's FDDI MIB for SMT 7.3 (RFC 1512) and MIB II (RFC 1213) parameters for use by NetView for AIX or any original equipment manufacturer (OEM) SNMP-based network management system.

Network management is further enhanced by use of the complementary FDDI SNMP Proxy Agent on the OS/2 platform. This agent will convert SMT to SNMP protocols for use by NetView for AIX or any OEM SNMP-based network management system.

For further information please refer to IBM 8244 FDDI Workgroup Concentrator: User' Guide.

5.19.5 IBM 8250 Multiprotocol Intelligent Hub

The IBM 8250 Multiprotocol Intelligent Hub is a family of products designed to provide the platform to build LANs meeting the requirements of customers using various types of cabling systems (such as STP, UTP, fiber and coax) and different types of LANs (such as token-ring, Ethernet, and FDDI).

The 8250 family consists of four models of rack-mountable chassis, each offering an advanced backplane architecture, which allows the concurrent operation of several LANs using various LAN protocols. A range of media and management modules are also provided to allow the design of networks addressing the individual needs of each organization.

8250 modules can be added, removed or reconfigured while the 8250 is in operation. This allows changes to the configuration of the network without affecting the operation of the other users on the network.

For management purposes you need at least one management module per hub. This module can be one of the available management modules, a basic token-ring management module for example. Each of these modules includes a media access adapter, depending on the type of module, for in-band management and a RS-232 interface for out-of-band management. The module also includes the SNMP agent function with MIB II and a specific 8250 MIB and a TELNET server for remote configuration. The management module has access to all other modules residing in the same hub via the management bus on the backplane. This gives you the ability to change the port assignments for example of a token-ring media module from an Ethernet management module without the need to buy a protocol specific management module for each supported protocol in the hub. Of course you won't get any media specific statistics or failures from another segment or LAN type.

The microcode update can be done by TFTP.

Management can be simplified by using the graphical application IBM Intelligent Hub Manager for AIX.

The newest 8250 MIB is available from the anonymous FTP server: on the Internet.

For further information please refer to IBM 8250 Multiprotocol Intelligent Hub and IBM 8260 Multiprotocol Intelligent Switching Hub Planning and Site Preparation Guide.

5.19.6 IBM 8260 Multiprotocol Intelligent Hub

The 8260 is IBM's newest intelligent hub. It is a hub platform for enterprise networking with an option of ATM for future growth. It can use existing 8250 modules so customers who have invested in 8250s can move to the 8260 without discarding their modules.

It can be used as a data center hub for consolidation of enterprise network functions. It also can be used as a wiring closet hub for port concentration and management.

It has all the features of the 8250 and the following new features:

The management of the 8260 hub is similar to the 8250 but more flexible. You can manage multiple LAN segments concurrently with only one management module because of the distributed architecture. The SNMP agent with the MIB II, the 8260 specific MIB, the TELNET server and all the IP functionality resides in the Distributed Management Module (DMM). The media access is provided by Media Access Cards (MAC) which can reside either as daughter cards directly on the media module or on the DMM carrier module. With this architecture you can "watch" up to 6 segments with only one DMM card. This saves space for other media modules and increases the maximum port density.

Management can be simplified by using the graphical application IBM Intelligent Hub Manager for AIX.

ATM management

The 8260 Switch/Control Point Module implements an SNMP ATM agent that includes objects defined by the standards bodies, as well as IBM specific extensions for superior manageability of ATM networks from the network management station

This SNMP agent features the following functions:

With the graphical application IBM ATM Campus Manager for AIX the management is greatly simplified.

The newest 8260 MIB is available from the anonymous FTP server: on the Internet.

For further information please refer to IBM 8250 Multiprotocol Intelligent Hub and IBM 8260 Multiprotocol Intelligent Switching Hub Planning and Site Preparation Guide.

Table of Contents Connectivity Summary