5-5
Catalyst 2950 Desktop Switch Software Configuration Guide
78-14982-01
Chapter 5 Configuring IE 2100 CNS Agents Understanding CNS Embedded Agents

Understandin g CNS Embedde d Agents

The CNS event agent feature allows the switch to publish and subscribe to events on the event bus and
works with the CNS configuratio n agent. The CNS configuration agent feature supports the switch by
providing:
Initial configurations
Incremental ( partial) configurations
Synchroniz ed c on figuration updat es

Initial Configuration

When the switch first comes up, it attempts to get an IP address by broadcasting a Dynamic Host
Configuration Prot ocol (DH CP) request on the network . Assuming there is no DHC P server on the
subnet, the d istrib ution swit ch acts as a DHCP relay agen t and forw ards the requ est to the DHCP serve r.
Upon re ceiving the reque st, the DH CP se rver a ssigns an I P addr es s t o t he new switch and i nclu des t he
Trivia l File Transfer Pr otoc ol (T FTP) 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 t he reply to the switch.
The switch automatically configures the assigned IP address on interface VLAN 1 (the default) and
downloads the b ootst rap c onfigurati on file fro m the T FTP ser ver. U po n su cce ssfu l download of the
bootstrap configuratio n file, the switch loads the file in its ru nning con figuration.
The embedded CNS agents initiate communication with the IE2100 Configuration Registrar by using the
appro pria te c onfigID and eventID. T he Co nfigur ati on Regi stra r m aps t h e co nfigID to a t emp la te and
downloads the full configuration file to the switch.
Figure 5-2 sh ows a sample network configuratio n for retrieving the initial bootstr ap configuration file
by using DHCP-base d autoco nfiguration.
Figure 5-2 Initial Configuration Overvi ew
TFTP
server
DHCP relay agent
default gatewayDistribution layer
IE2100
Configuration
Registrar
Access layer
switches
71445
DHCP
server
VWAN