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Catalyst 2950 Desktop Switch Software Configuration Guide
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Chapter 5 Configuring IE 2100 CNS Agents Understanding IE2100 Series Configuration Registrar Software

CNS E ven t Serv i ce

The Configuration Registrar uses the CNS Event Service for receipt and generation of configuration
e ven ts. The CNS e v ent agen t resides on the switch an d faci litates the communicati on between the switch
and th e event gateway on the C onfigura tion Registra r.
The CNS Event Service is a highly-scalable publish-and-subscribe communication method. The CNS
Event Service uses subject-based addressing to send messages to their destinations. Subject-based
addressi ng conventions define a simple, uni form namespa ce for message s and their de stination s.

NameSpace Mapper

The Confi guration Registrar includes the NameSpace Mapper (NSM) that provides a lookup service for
managing l ogic al gr oup s of d evices base d on ap pli cat ion, device ID or gr oup ID, and event.
Cisco IO S devices rec ognize on ly event subject-n ames tha t mat ch th ose configured i n Ci sco I OS
software; f or exampl e, c isco .c ns.co nfig.loa d. You can use the nam esp ace m appi ng ser vi ce to de signa te
events by using a ny desired nam in g convention . Whe n you have populat ed you r d ata st o re w ith y our
subject name s, N SM re solves your event subject -nam e st ring s to those k nown by IOS.
For a subs crib er, when gi v en a u niq ue device ID an d even t, the nam esp ace ma ppin g serv ice re tur ns a set
of ev ents to which to subscribe. Similarly , for a publisher, when given a unique group ID, device ID, and
event , t he m a pping serv ice r etur ns a set of events on whi ch t o publ ish.

What You Should Know About ConfigID, DeviceID, and Host Name

The Configuration Re g i st r ar assum e s tha t a un iq ue identifier is associated with each co nfigured switch.
This uni que iden tif ier c an t ake on multiple synon yms, where e ach synon ym is u nique w ithin a partic ular
namespace. The event service uses namespace content for subject-based addressing of messages.
The Con fi gurat ion Registrar inte rsects two nam espaces , one for the event bus and the other for the
configuration server. Within the scope of the con figuration server namespace, the ter m configID is the
unique identifier for a device. Within the scope of the event bus namespace, the term deviceID is the
CNS uni que i den tifier for a device.
Because the Configuratio n Registrar uses bot h the event bus and the configur ation server to provide
configurati ons to devices, you must define both configID an d deviceID for each co nfigured swit ch.
Within the scope of a single instance of the configuration server, no two configured switches can share
the same value for configID. Within the scope of a single in stance of the event bu s, no two configured
switches can share the same value for deviceID.

ConfigID

Each configured switch has a unique configID, which serves as the ke y into the Configuration Registrar
directo ry for the co rresp onding s et of switch CLI attributes. The configID defined on the sw itch must
match t he c onfigID f or the cor res pondi ng switc h de finition on t he Configura tion R egistrar.
The configID is fixed at boo t time and cannot be changed until r eboot, even when the switch host name
is reconfigured.