Significance of context name in snmpv3

Question

Snmpv3 is a secured protocol compared to Snmpv2 and Snmpv1. But I dont understand what is the use of context name.We already have an user name and also authentication and privacy passwords which provide a security level. Someone using a wireshark cannot identify it as it is sent through encrypted form. So what is the use of context name in Snmpv3?

Denise

Answer 1

The contextName and contextEngineID parameters allow multiple versions of the same MIB objects to be made available by a single SNMPv3 engine, as if you have multiple agents running on the same IP address and port. These are distinguished from one another by contextName and contextEngineID, where otherwise they would have had a different address and/or port. One reason for this could be that you have a master agent with multiple sub-agents and the sub-agents have some overlap. Another reason would be a proxy agent: for example, a manager that only speaks SNMPv3 and devices than only speak SNMPv1 could use a multi-lingual proxy at a single address/port and use the contextName and contextEngineID to identify devices. The proxy here would map the contextName and contextEngineID to device address/port and translate/forward requests to the devices and responses back to the manager.

Crumhorn