Linksys SLM224G4S Manuel d'utilisateur télécharger pdf (Page 60)

About Switch Stacking

Appendix B

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

If the incoming unit did not have an assigned Unit

ID (that is, it was in factory default mode), it will

be assigned the lowest available Unit ID by the

Master. It is strongly recommended that automatic

assigned unit ID mode be used since it provides

better resiliency to the stack.

If the incoming unit already has an assigned Unit

ID, and that Unit ID is unused in the current stack,

the incoming unit will keep its assigned Unit ID

and the Master will apply to it any configuration

relevant to that Unit ID.

If the incoming unit already has an assigned Unit

ID, and that Unit ID conflicts with a unit ID in the

current stack, the Master will reallocate a new

Unit ID to the incoming unit, giving it the lowest

available Unit ID (assuming, of course, that the

incoming unit does not have a manually assigned

Unit ID, which the Master cannot change).

If the incoming unit cannot be assigned an

available Unit ID for any reason (in the case of unit

replacement that can only happen if the incoming

unit has a manually assigned Unit ID), then it will

be effectively shut down—that is, it will not be

joined to the stack.

The stack Master will now carry out Unit and port

configuration for the incoming unit.

Any configuration information the Master has

that is relevant to the number assigned to the

incoming unit will be applied. In particular, if the

incoming unit was assigned the same Unit ID of

the unit it replaces, then it will receive the same

configuration as the failed unit, to the extent

possible.

If the incoming unit is identical in makeup to the

replaced unit, the entire configuration of the replaced

unit will be applied to the incoming one and the stack

will go back to the state it was in before unit failure.

However, sometimes the incoming unit is not identical

to the unit that failed in these cases. The stack Master

will apply the configuration in the following manner:

If a 24-port unit replaces a failed 48-port unit,

then the ports of the incoming unit will be

configured according to the way the first 24

ports of the failed unit were configured.

(Note that the configuration of all 48 ports of the

failed unit is remembered, even though only the

first 24 are currently applied. If, in the future, a 48

port unit is inserted and assigned the same Unit

ID, it will be configured as the original failed 48-

port unit was configured).

•

If a 48-port unit replaces a 24-port unit, then

the first 24 ports of the incoming unit will be

configured according to the way the ports of the

failed unit were configured, and the rest of the

ports of the incoming unit will be configured at

default settings.

If the units (the failed one and its replacement)

had/have uplink ports, then the first uplink of

the incoming unit will be configured as was the

first uplink of the failed unit, and so on.

Stack Master Failure and Replacement

In this example, the master unit fails in a running stack.

When notified of the failure, a system administrator

removes the failed unit and replaces it with another one.

When the unit fails, the stack Backup Master detects (via

the ongoing monitoring Master Discovery process) that

the master unit no longer responds and takes over as the

stack master. The backup master directs all other stack

members to route unit-to-unit traffic around the failed

unit using the ring topology of the stacking connections.

At the same time the stack Backup Master notifies the

system administrator (using SYSLOG messages and SNMP

traps) of the failure.

When the failed unit is disconnected from the stack, all

traffic will already be routed around it, and as long as all

other stacking connections are left intact, the stack should

continue to run.

When a new unit is inserted in the stack and powered up,

the following will happen:

The incoming unit will perform Master discovery, and

perhaps participate in a Master Election, as described

above.

If the incoming unit has a Unit ID of 1 or 2 (that

is, the unit is a master-enabled unit), then Master

Election will be initiated. However, since the

running stack Backup Master has a longer run

time, assuming that it has been running for more

then 10 minutes, it will remain elected as the stack

Master and the incoming unit will not become a

new stack Master. This may result in an incoming

unit using Unit ID=1, and serving as the stack

backup master, while the already running unit

with Unit ID=2 remains the active stack master.

The stack Master at this stage will carry out a Unit ID

allocation and conflict resolution process.

If the incoming unit did not have an assigned Unit

ID (that is, it was in factory default mode), it will

be assigned the lowest available Unit ID by the

Master. It is strongly recommended that automatic

assigned unit ID mode be used since it provides

better resiliency to the stack.

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Linksys SLM224G4S Manuel d'utilisateur Page 60

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