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Cisco IE 2000 Switch Software Configuration Guide
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Chapter 5 Configuring Cisco IOS Configuration Engine
Information About Configuring Cisco IOS Configuration Engine
The origin of the DeviceID is defined by the Cisco IOS hostname of the switch. However, the DeviceID
variable and its usage reside within the event gateway adjacent to the switch.
The logical Cisco IOS termination point on the event bus is embedded in the event gateway, which in
turn functions as a proxy on behalf of the switch. The event gateway represents the switch and its
corresponding DeviceID to the event bus.
The switch declares its hostname to the event gateway immediately after the successful connection to
the event gateway. The event gateway couples the DeviceID value to the Cisco IOS hostname each time
this connection is established. The event gateway caches this DeviceID value for the duration of its
connection to the switch.

Hostname and DeviceID Interaction

The DeviceID is fixed at the time of the connection to the event gateway and doe s not change even when
the switch hostname is reconfigured.
When changing the switch hostname on the switch, the only way to refresh the DeviceID is to break the
connection between the switch and the event gateway. Enter the no cns event global configuration
command followed by the cns event global configuration command.
When the connection is reestablished, the switch sends its modified hostname to the event gateway. The
event gateway redefines the DeviceID to the new value.

Using Hostname, DeviceID, and ConfigID

In standalone mode, when a hostname value is set for a switch , the configuration server uses the
hostname as the DeviceID when an event is sent on hostname. If the hostname has not been set, the event
is sent on the cn=<value> of the device.
In server mode, the hostname is not used. In this mode, the u nique DeviceID attribute is always used for
sending an event on the bus. If this attribute is not set, you cannot update t he switch.
These and other associated attributes (tag value pairs) are set when you run Setup on Configuration
Engine.
Cisco IOS Agents
The CNS event agent feature allows the switch to publish and subscribe to events on the event bus and
works with the Cisco IOS agent.

Initial Configuration

When the switch first comes up, it attempts to get an IP address by broadcasting a DHCP request on the
network. Assuming there is no DHCP server on the subnet, the distribution switch acts as a DHCP relay
agent and forwards the request to the DHCP server. Upon receiving the r equest, the DHCP server assigns
an IP address to the new switch and includes the TFTP server IP address, the path to the bootstrap
configuration file, and the default gateway IP address in a unicast reply to the DHCP relay agent. The
DHCP relay agent forwards the reply to the switch.
The switch automatically configures the assigned IP address on interface VLAN 1 (the default) and
downloads the bootstrap configuration file from the TFTP server. Upon successful download of the
bootstrap configuration file, the switch loads the file in its running configuration.