Skip to main content

Device 0004 - IBM 8228 TokenRing MAU

8228-001 IBM Token-Ring Network Multistation Access Unit Model 001

Id: D0004

Description:

The 8228 - an unmanaged hub - has 8 token ring user ports which use the IBM Cabling System (ICS) connectors; a media filter can be used to attach an RJ-45 token ring cable to the 8228. The 8228 has no external power supply; all its power requirements are provided by the connecting token ring adapters themselves which cause relays inside the 8228 to operate when a connection is made. There are no indicator lights on the 8228, so there is no way to know whether or not any particular port is in use or not.

The 8228 also has ring-in and ring-out ports, which can be used to link to other 8228s to form a complete ring. Two 8228s can be connected using a single cable between one unit’s RO port and the other unit’s RI port; greater resilience will be provided for networks of two or more 8228s if all RI/RO ports are attached, with the RO port of the last 8228 being connected back to the RI port of the first 8228. Doing this will allow the ring to remain active and complete even if any one of the RI/RO cables should fail or be disconnected. If the 8228 is to be used on its own then it is not necessary to connect the ring-out port to the ring-in port to complete the ring.

In a ring formed solely of 8228s, the speed at which the ring operates (4 Mbps or 16 Mbps) is determined by the first device to connect to the ring. This sometimes causes problems when the first device is set to auto-sense the speed of the ring: because there is not yet any ring activity it is unable to determine which speed to use and is unable to connect. This sometimes requires pre-configuration of ring speed in one or more devices. Watch out, however, because if the ring is operating at one speed (say 16 Mbps) and a new device is pre-configured with the other speed (4 Mbps in this case), attaching the new device to the 8228 will cause the ring to break. No recovery is possible until the offending device is disconnected from the 8228. The only totally fool-proof mode of operation is one in which all connecting devices are pre-configured with the same ring speed.

Type: Communications::Network::TokeRing

Links

Comments

Post a Comment

Popular posts from this blog

Movies - The Bubble (2022)

  Back to Evolution (2001) .
Post a Comment
Read more

IT - Fixing Windows Error 1327: Account Restrictions Are Preventing This User from Signing In

Fixing Windows Error 1327: Account Restrictions Are Preventing This User from Signing In Introduction Error 1327, “Account restrictions are preventing this user from signing in,” is a perplexing and disruptive issue that occurs on some Windows 10 and Windows 11 machines. The message typically appears at login or while connecting to remote resources, like shared folders, network drives, or remote desktops. Table of Contents Symptoms of Error 1327 Common Causes Step-by-Step Troubleshooting Advanced Fixes Automation via PowerShell Prevention Tips Further Reading Symptoms of Error 1327 Users experiencing this error may encounter one or more of the following: Login screen fails after credentials are entered. Error message appears when accessing mapped drives or network resources. Remote Desktop Connection (RDP) is rejected with the 1327 message. Group Policy logon restrictions silently block access. Co...
Post a Comment
Read more

ATA Drive Capacity Limitations

ATA interface versions up through ATA-5 suffered from a drive capacity limitation of about 137GB (billion bytes). Depending on the BIOS used, you can further reduce this limitation to 8.4GB, or even as low as 528MB (million bytes). This is due to limitations in both the BIOS and the ATA interface, which when combined create even further limitations. To understand these limits, you have to look at the BIOS (software) and ATA (hardware) interfaces together. NOTE In addition to the BIOS/ATA limitations discussed in this section, various operating system limitations exist. These are described later in this chapter. The limitations when dealing with ATA drives are those of the ATA interface as well as the BIOS interface used to talk to the drive. A summary of the limitations is shown in Table 7.12. Table 7.12. ATA/IDE Capacity Limitations for Various Sector Addressing Methods Sector Addressing Method Total Sectors Calculation Maximum Total Sectors Maximum Capacity (Byte...
Post a Comment
Read more