D-Link 3100 48 User Manual - Page 30

DGS-3100 Series Gigabit Stackable Managed Switch User Manual These stacking members do not participate in the Master Election process, and if no Stack Master is present, the stacking members' network ports are shut down. Only the stacking ports are operational. Both the Stack Master and all other stacking members carry out a continuous process of Master Discovery by frequently exchanging stack control messages. This allows the stacking members to discover when a stacking member fails or is unreachable. Allocating Unit IDs/Resolving Unit ID Conflicts Once the Stack Master is elected, it allocates the Unit IDs to the stacking members that do not have a Unit ID. Stacking members that do not have a Unit ID operate in the Factory Default mode. In addition, the stack Master attempts to resolve all duplicate Unit IDs occurrences among stacking members. The Stack Master reallocates the duplicate Unit ID if there are available Unit IDs. If two stacks are merged, stacking units that were initially in the Stack Master's sub-group retain their Unit ID. New stacking member are allocated new Unit IDs. If a conflict occurs after the stacking members are rebooted, the following occurs: • If both duplicate stacking members are in Auto Assign mode, then the Unit ID is assigned by the MAC address. The stacking member with the lowest MAC address maintains its Unit ID. The other stacking member is assigned a new Unit ID. • If one of the stacking members with duplicate Unit IDs is in Auto Assign mode and the other stacking member is in manual mode, the stacking member in Manual mode maintains its Unit ID, The other stacking member is assigned a new Unit ID. . Stacking members are shut down if: • If both duplicate stacking members are in Manual mode then both stacking members are shut down. • If the Stack Master is able to allocate a Unit ID to each stacking member, then all stacking members operate as a stack. If the Stack Master is unable to allocate a Unit ID to any stacking member, that stacking member is effectively shut down and does not participate in the stack. • Stacking members with a conflicting manually set ID are shut down as the Stack Master cannot override the system administrator's Unit ID assignment to resolve the conflict. • If there are more stacking members than the maximum number allowed in a stack, and the incoming stacking members are already in Factory Default mode, the Stack Master is elected following Master Discovery and Master Election processes. All other stacking members are shut down in some extreme cases, due to during the boot process, where some stacking members may be connected and join the stack. If the new stacking members are already assigned a Unit, then the new stacking members cannot join the stack. The switches are remains shut down. If a stacking member is shut down, the stacking members stacking links are inactive. Moreover, if the stacking members are connected in a chain topology, the shut down of one stacking member breaks the chain. This may cause other stacking members to be disconnected and shut down if the stacking members have no active link to the Stack Master. Unit and Stacking Port Configuration Each stacking member has a Unit ID; one of the stacking members is the stack Master, and, possibly, one of the stacking members serves as Backup Master. The Stack Master now configures each stacking member according to the Configuration file stored on the Stack Master. If the stack has a Backup Master the Configuration file are also be copied to the Backup Master. Once all the stacking members are configured, the stack proceeds to a normal operational mode. If any change is made to the system configuration, the change is stored by the stack Master and is copied to the Backup Master. 18