Linksys SLM224G4S Manuel d'utilisateur télécharger pdf (Page 57)

About Switch Stacking

Appendix B

24/48-Port 10/100 + 4-Port Gigabit Resilient Clustering Smart Switch with 2 Combo SFPs

the Console port, Telnet or Web-based Utility) and reset

the units to make this assignment permanent.

The unit that is assigned number 1 will act as the Master;

this is indicated by the Stack Master LED on its front panel

being lit amber. The unit that is assigned number 2 will act

as the Backup Master.

Stack Resiliency

A stack’s topology may be either Ring or Chain. The best

practice is to configure the stack in Ring topology, due to

its higher resiliency in case of unit failure or stacking link

failure.

Additionally, if a redundant power supply is used, it is

recommended to make sure that the Master and Backup

Master units are connected to the redundant power

supply.

Advanced Stacking

In order to understand the operation of the stack it is

necessary to understand two key concepts:

Unit IDs, and how they are allocated

Stack unit start up process

Unit IDs

Each unit in a stack has an assigned unique Unit ID number.

Unit ID numbers are meaningful as follows:

The unit that is assigned Unit ID=1 will serve as the

Stack Master. All other units will be stack members.

The stack Master provides a single point of control,

configuration and management for the entire stack,

and stores the configuration for all stack members

(which themselves do not store any configuration

information at all).

The unit that is assigned Unit ID=2 is a special stack

member, which serves as the Stack Backup Master.

A stack Backup Master, in addition to being a stack

member, serves as a Backup in case the stack Master

fails or is disconnected for any reason. If that should

happen, the Backup Master takes over the role of stack

Master for the remaining stack members.

To make this possible, the stack Master will store a copy

of the active configuration on the Backup Master, but

this copy will only be used if and when it takes over the

role of stack Master. Note that only the configuration

file is copied. Any dynamically filled tables, e.g.

addresses learned, are not copied from the Master to

the Backup Master. If the Backup Master takes over

the role of stack Master, it will start building its own

dynamic tables from scratch.

•

Units that are assigned Unit IDs 3-6 (SLM224G4S) or

Unit IDs 3-4 (SLM248G4S) are called Stack Members.

A stack member will only operate as a member of

the stack under the direction of an operational stack

Master (or a Backup Master that has taken over the

role).

Stack members are not directly manageable and

configurable, and must be managed through the

stack Master, and do not contain any meaningful

configuration information (not even their own

configuration). If an operational master is not present

and reachable, these units will not be functional.

Master Enabled units

Units that are assigned a unit ID number of 1 or 2 are

called master enabled units. Only master enabled units

participate in master election (see below) whenever

they are initiated, inserted into a new stack or lose

connectivity with the existing master. Only master

enabled units can become the stack master or backup

master. Units with assigned IDs of 3-6 (SLM224G4S)

or 3-4 (SLM248G4S) can become neither a master nor

a backup master unless this is done manually by the

system administrator or they are reset to the factory

default first.

Unit ID Allocation

Units are shipped from the factory with no Unit ID, and

must be assigned a unique Unit ID before they can operate

as part of a stack. Unit ID numbers are assigned to units in

one of two ways:

Assigned by the system administrator, in which case

they can only be changed manually by the system

administrator

Allocated to a stack member unit by the stack Master

during system initialization

In general, a unit that was assigned a Unit ID will tend

to keep this number even after it is rebooted. The stack

Master may reallocate Unit IDs during system initialization

to resolve duplicate Unit ID conflicts (see below). Manually

assigned Unit IDs cannot be changed by the stack Master,

even if they are in conflict.

Unit ID assignment/change takes effect only during

system initialization and does not take place during run-

time of the system.

Units of a stack do not have to be numbered in sequence

or in order, and may be interconnected as desired, as long

as each unit has a unique ID and at least one unit of the

stack serves as stack Master.

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1 2 ... 52 53 54 55 56 57 58 59 60 61 62 ... 76 77

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Linksys SLM224G4S Manuel d'utilisateur Page 57

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