D-Link DGS-3312SR Release 3.5 Manual page 253

It is not a CS or MS of another IP group.
It is connected to the CS through the CS management VLAN.
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Candidate Switch (CaS) – This is a switch that is ready to join a SIM group but is not yet a member of the SIM
group. The Candidate Switch may join the SIM group through an automatic function of the DGS-3312SR, or by manually
configuring it to be a MS of a SIM group. A switch configured as a CaS is not a member of a SIM group and will take on
the following characteristics:
It is not a CS or MS of another Single IP group.
It is connected to the CS through the CS management VLAN
The following rules also apply to the above roles:
→
Each device begins in a Commander state.
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CS's must change their role to CaS and then to MS, to become a MS of a SIM group. Thus the CS cannot
directly be converted to a MS.
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The user can manually configure a CS to become a CaS.
A MS can become a CaS by:
→ Being configured as a CaS through the CS.
→ If report packets from the CS to the MS time-out.
→ The user can manually configure a CaS to become a CS
→ The CaS can be configured through the CS to become a MS.
After configuring one switch to operate as the CS of a SIM group, additional DGS-3312SR switches may join the group
either by an automatic method or by manually configuring the Switch to be a MS. The CS will then serve as the in band
entry point for access to the MS. The CS's IP address will become the path to all MS's of the group and the CS's
Administrator's password, and/or authentication will control access to all MS's of the SIM group.
With SIM enabled, the applications in the CS will redirect the packet instead of executing the packets. The applications
will decode the packet from the administrator, modify some data, and then send it to the MS. After execution, the CS may
receive a response packet from the MS, which it will encode and send it back to the administrator.
When a CaS becomes a MS, it automatically becomes a member of the first SNMP community (include read/write and
read only) to which the CS belongs. However, if a MS has its own IP address, it can belong to SNMP communities to
which other switches in the group, including the CS, do not belong.
All DGS-3312SR switches are set as Candidate (CaS) switches, as their factory default configuration and the Single IP
Management feature will be disabled. To enable SIM for the Switch using the Web interface, go to the Single IP
Management folder and click the SIM Settings link, revealing the following window.
DGS-3312SR Stackable Gigabit Layer 3 Switch
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