D-Link xStack DGS-3420 Series Reference Manual page 52

xStack® DGS-3420 Series Layer 2 Managed Stackable Gigabit Switch Web UI Reference Guide
SIM group, and a Candidate Switch (CaS), which is a Switch that has a physical link to the SIM group but
has not been recognized by the CS as a member of the SIM group.
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A SIM group can only have one Commander Switch (CS).
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A SIM group accepts up to 32 switches (numbered 1-32), not including the Commander Switch (numbered
0).
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Members of a SIM group cannot cross a router.
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There is no limit to the number of SIM groups in the same IP subnet (broadcast domain); however a single
switch can only belong to one group.
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If multiple VLANs are configured, the SIM group will only utilize the default VLAN on any switch.
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SIM allows intermediate devices that do not support SIM. This enables the user to manage switches that
are more than one hop away from the CS.
The SIM group is a group of switches that are managed as a single entity. The Switch may take on three different
roles:
1. Commander Switch (CS) – This is a switch that has been manually configured as the controlling device
for a group, and takes on the following characteristics:
a. It has an IP Address.
b. It is not a command switch or member switch of another Single IP group.
c. It is connected to the member switches through its management VLAN.
2. Member Switch (MS) – This is a switch that has joined a single IP group and is accessible from the CS,
and it takes on the following characteristics:
a. It is not a CS or MS of another IP group.
b. It is connected to the CS through the CS management VLAN.
3. 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 of the Switch 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:
a. It is not a CS or MS of another Single IP group.
b. It is connected to the CS through the CS management VLAN
The following rules also apply to the above roles:
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Each device begins in a Candidate state.
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CSs 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.
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A MS can become a CaS by:
Being configured as a CaS through the CS.
o
If report packets from the CS to the MS time out.
o
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The user can manually configure a CaS to become a CS
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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-3420 Series switches may join
the group 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 (includes 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.
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