IBM 8237, Инструкция по установке и эксплуатации

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Chapter 1 Introduction and Planning
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You can also interconnect 8237s in different backplanes using a bridge, router, or
Ethernet switch.
In order to manage a stack of 8237s:
•
The 8237 you want to manage must be a Model 002 or Model 003, or it must be
connected in a stack that includes at least one Model 002 or Model 003, and
•
There must be an Ethernet link between the 8237 to which your management
workstation is attached and the Model 002 or Model 003 that is serving as the
primary management unit for the stack.
Assigning Backup Port Pairs
A managed stack provides the option of making redundant connections to network-
critical devices, such as servers or LAN switches. You can use the VT100 interface
or any SNMP-based network management application to assign backup port pairs.
These ports are called the
primary
and
secondary
ports. Any port in an 8237,
including those on Expansion Ports, can be used as a backup for any other port. A
stack can have up to 18 pairs of redundant ports. The primary and secondary ports
can be on separate backplanes. Note that you must establish two physical
connections to the desired device.
When a backup port pair has been configured and activated, the primary port will be
enabled and the secondary port will be disabled to prevent looping. When a backup
port pair is operating, the Link/Activity LED will indicate activity on the
primary port
and the Partition LED for the secondary port will be on.
If the connection to the primary port is broken, the secondary port will be enabled to
keep the device connected. The Link/Activity LED will indicate activity on the
secondary
port and the Partition LED for the
primary
port will be on. When you
reset the backup function, the secondary port will be disabled and the primary port
will be re-enabled.
Ethernet Planning
The size of each Ethernet collision domain you create is limited by these factors:
•
The cable length restrictions unique to each type of segment (that is, for
10BASE-T, 100BASE-TX, 10BASE2, 10BASE-FL, FOIRL).
•
The limit of four repeaters between any two devices in one collision domain.
These factors are explained in greater detail in the following sections.