IBM Token-Ring Network Bridge Program V1.1

The prime function of IBM Token-Ring Network Bridge Program V1.1 is to interconnect 4 Mbps IBM Token-Ring Network segments at the MAC level. Ring stations initiate source routing protocols to resolve the route to a destination station on a separate ring segment. Although still supported, IBM Token-Ring Network Bridge Program V1.1 has been superseded by IBM Token-Ring Network Bridge Program V2.0.

In addition, IBM Token-Ring Network Bridge Program V1.1, via a component called the LAN reporting mechanism, is capable of establishing a reporting link with up to four IBM LAN Manager V1.0s. Each reporting link is an IEEE 802.0 logical link control Type 2 (connection-oriented) link, dedicated to transport network management information in either direction.

LAN management functions and products are discussed in a separate Chapter

"LAN Management and Recovery" on page 253. Some LAN management commands change the way in which a LAN segment operates. When a bridge has a reporting link with several IBM LAN Managers to control the same LAN segment, those commands must be reserved to one LAN Manager only to avoid conflicts. This LAN Manager is called the controlling LAN Manager for a given bridge. All other (up to three) LAN Managers to which this bridge reports are called observing LAN Managers.

The link between a bridge and its controlling LAN Manager is reporting link 0, also referred to as authorization level O. Once a reporting link 0 is established, IBM Token-Ring Network Bridge Program V1.1 will reject subsequent attempts . by other IBM LAN Managers to establish a reporting link 0, thereby avoiding

duplicate controlling LAN Managers.

6. Bridges

165

166

LAN Concepts

Observing LAN Managers have reporting links 1, 2 or 3 with a given bridge.

Reporting links are always initiated by the LAN Manager station, either at LAN Manager initialization or during LAN Manager operation by the network operator through a link Bridge command. The operator may also decide to unlink a reporting link. 'Establishing a reporting link requires the operator to provide a link password.

The IBM Token-Ring Network Bridge Program V1.1 may receive requests from IBM LAN Manager V1.0, and send back appropriate responses over a reporting link after executing a given request on an attached ring segment.

In addition, the IBM Token-Ring Network Bridge Program V1.1 may receive commands, reserved to the controlling IBM LAN Manager V1.0, over reporting link

o.

For IBM Token-Ring Network Bridge Program V1.1, these commands are:

• Set single-route broadcast in a bridge.

• Remove station on a ring segment.

• Set soft error logging options for a ring segment.

• Perform a path test.

The communication between IBM LAN Manager V1.0's and IBM Token-Ring Network Bridge Program V1.1 is shown in Figure 76 on page 167.

Observing Controlling Observing Observing LAN t;lanagers

DDDD

Reporting Links (LLC Type 2)

3 8

*

****

2 1

Bridge Program ~--- ----*---- ---- ---~

LAN Reporting Mechanism (LRM)

$$$$

MAC Router

Ring Segments

Ring:J

L - - - - LAN application LLC session - - - J

Figure 76. IBM Token-Ring Network Bridge Program V1.1 - IBM LAN Manager V1.0 Communication

This figure summarizes both the application flow between end stations (carrying data and higher-level-protocol header information), and network management data flow. The latter consists of LLC Type 2 sessions between LAN Manager and the LAN reporting mechanism which directs a LAN Manager

request/command to the appropriate server function in the Bridge. On the ring segments side, LAN Manager requests/commands are translated into the appropriate MAC frames for execution on one of the two attached ring

segments. Responses provided by the appropriate server function are directed to the LAN reporting mechanism which packages them into an LLC frame addressed to the originating LAN Manager.

Various server functions are also illustrated. Some of these, associated with network management, are optional, while the LAN Bridge Server is always present.

6. Bridges

167

168

LAN Concepts

LAN Bridge Server

The bridge processing by the,LBS function consists of:

.. Reading and validating bridge parameters from a configuration file at bridge initialization time and whenever a controlling LAN Manager modifies bridge parameters.

• Performing the bridge self-test during bridge initialization or upon request from an operator through the bridge user interface. This test includes detection of duplicate parallel paths and invalid network configurations (that is inconsistent ring numbering).

• Maintaining a set of performance counters for each adapter, including counters for the number of frames discarded, not received or not forwarded for any other reason, and for the number of frames and bytes forwarded (both for broadcast and non-broadcast frames). On request, the

accumulated values may be reported to, LAN Manager.

• Accumulating path trace information for frames carrying a system path trace bit set on in the routing information control field. Path trace report frames may be sent to the controlling LAN Manager.

The different bridge server functions which may be enabled optionally on each of the bridge token-ring adapters are also shown in Figure 76 on page 167.

Ring Error Monitor

The REM server function in the bridge compiles error statistics irom received Soft_ Error_ Report MAC frames and selectively generates reports for LAN Manager, depending on the soft error reporting mode (normal/intensive) set by LAN Manager.

Ring Parameter Server

In addition to supplying the ring number to stations in response to

RequestJnit_Parameters MAC frames received by RPS during ring insertion, the RPS function also notifies LAN Manager when a given station has entered the LAN segment. A specific bridge protocol assures that only one RPS function is active on each ring segment.

Configuration Report Server

The CRS function forwards configuration notifications to LAN Manager. Upon receipt of a MAC level configuration notification, it transmits the received information via the LAN reporting mechanism to LAN Manager. From LAN Manager, CRS accepts such commands as Query Adapter, Remove Adapter and Set Station Parameters for execution on a bridge-attached LAN segment.

IBM TOken-Ring Network Bridge Program V1.1 Implementation: The software component consists of IBM PC/DOS 3.3 or 4.0 and IBM Token-Ring Network Bridge Program V1.1 (5871-AAA). The IBM Token-Ring Network Bridge

Program V1.1 includes the direct and logical link control device driver modules.

IBM Token-Ring Network Bridge Program V1.1 also comes with a menu-driven bridge configuration utility, supporting specification of user-modifiable bridge parameters.

IBM Token-Ring Network Bridge Program V1.1 requires a dedicated PC AT, Industrial Computer 7531 or 7532, or any PS/2 model with 256 Kbytes of memory. It attaches to two 4 Mbps Token-Ring Network segments using two IBM Token-Ring Network Adapters II for Family 1 devices or two IBM

TOken-Ring Network Adapters I A for Family 2 devices. One adapter must be primary, the other alternate and the interrupt levels must be set to 2 and 3 respectively.

Bridge Installation: The IBM Token-Ring Network Bridge Program V1.1 diskette contains the following files:

• ECCMAIN.EXE (the main Bridge Program)

• ECCFEA2.EXE (the Ring Error Monitor Error Analysis Program)

• ECCCNFG.EXE (the Configuration Utility program)

• ECCPARMS.BIN (the default and initial bridge Parameters)

• ECCHELP.SCN (the help information file).

Installation begin with completion of the Bridge Planning Chart to determine the bridge parameters. Using this information, the ECCCNFG program is then executed to set the bridge parameters. The main bridge program, ECCMAIN, should be included in the AUTOEXEC.BAT file to allow automatic (re)start of the bridge.

IBM Token-Ring Network Bridge Program V1.1 is shipped with the IBM Token-Ring Network Bridge Program V1.1 User's Guide

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