Snmp Versions - Cisco ASR 9000 Series User Configuration Manual

SNMP Versions

several times. The retries increase traffic and contribute to a higher overhead on the network. Thus, traps and
inform requests provide a trade-off between reliability and resources.
In this illustration, the agent router sends a trap to the SNMP manager. Although the manager receives the
trap, it does not send any acknowledgment to the agent. The agent has no way of knowing that the trap reached
its destination.
Figure 9: Trap Received by the SNMP Manager
In this illustration, the agent sends a trap to the manager, but the trap does not reach the manager. Because
the agent has no way of knowing that the trap did not reach its destination, the trap is not sent again. The
manager never receives the trap.
Figure 10: Trap Not Received by the SNMP Manager
SNMP Versions
Cisco IOS XR software supports the following versions of SNMP:
• Simple Network Management Protocol Version 1 (SNMPv1)
• Simple Network Management Protocol Version 2c (SNMPv2c)
• Simple Network Management Protocol Version 3 (SNMPv3)
Both SNMPv1 and SNMPv2c use a community-based form of security. The community of managers able to
access the agent MIB is defined by an IP address access control list and password.
SNMPv2c support includes a bulk retrieval mechanism and more detailed error message reporting to
management stations. The bulk retrieval mechanism supports the retrieval of tables and large quantities of
information, minimizing the number of round-trips required. The SNMPv2c improved error handling support
includes expanded error codes that distinguish different kinds of error conditions; these conditions are reported
Cisco ASR 9000 Series Aggregation Services Router System Management Configuration Guide, Release 5.1.x
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Implementing SNMP