Ccna routing and Switching Complete Study Guide

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Simple Network Management Protocol (SNMP)

Simple Network Management Protocol (SNMP) collects and manipulates valuable net-

work information, as you can see in Figure 3.7. It gathers data by polling the devices on the 

network from a network management station (NMS) at fixed or random intervals, requir-

ing them to disclose certain information, or even asking for certain information from the 

device. In addition, network devices can inform the NMS station about problems as they 

occur so the network administrator is alerted.

f I g u r e   3 . 7    SNMP

MY FAN DIED! I’M BURNING

UP!! UGH!!

OKAY! I’ll sound 

the alarm!

NMS Station

When all is well, SNMP receives something called a baseline—a report delimiting the 

operational traits of a healthy network. This protocol can also stand as a watchdog over the 

network, quickly notifying managers of any sudden turn of events. These network watch-

dogs are called agents, and when aberrations occur, agents send an alert called a trap to the 

management station.

snmP versions 1, 2, and 3

SNMP versions 1 and 2 are pretty much obsolete. This doesn’t mean you won’t see them 

in a network now and then, but you’ll only come across v1 rarely, if ever. SNMPv2 pro-

vided improvements, especially in performance. But one of the best additions was called 

GETBULK, which allowed a host to retrieve a large amount of data at once. Even so, v2 

never really caught on in the networking world and SNMPv3 is now the standard. Unlike 

v1, which used only UDP, v3 uses both TCP and UDP and added even more security, mes-

sage integrity, authentication, and encryption.