Understanding How Snmp Works; Security Models And Levels - Cisco WS-C6506 Software Manual

Understanding How SNMP Works

Understanding How SNMP Works
SNMP is an application-layer protocol that facilitates the exchange of management information between
the network devices. SNMP enables the network administrators to manage network performance, find
and solve network problems, and plan for network growth.
There are three versions of SNMP:
•
•
•

Security Models and Levels

A security model is an authentication strategy that is set up for a user and the group in which the user
resides. A security level is the permitted level of security within a security model. A combination of a
security model and a security level determines which security mechanism is employed when handling
an SNMP packet. Three security models are available: SNMPv1, SNMPv2c, and SNMPv3.
identifies the combinations of security models and defines the levels for SNMPv1, SNMPv2c, and
SNMPv3.
Table 47-2
Model
v1
v2c
v3
v3
v3
Catalyst 6500 Series Switch Software Configuration Guide—Release 8.7
47-4
Version 1 (SNMPv1)—This version is the initial implementation of SNMP. Refer to RFC 1157 for
a full description of functionality. See the
section on page 47-5 for more information on SNMPv1.
Version 2 (SNMPv2c)—The second release of SNMP, described in RFC 1902, has additions and
enhancements to data types, counter size, and protocol operations. See the
SNMPv1 and SNMPv2c Work" section on page 47-5
Version 3 (SNMPv3)—This version is the most recent version of SNMP and is fully described in
RFC 2571, RFC 2572, RFC 2573, RFC 2574, and RFC 2575. The SNMP functionality on the
Catalyst enterprise LAN switches for SNMPv1 and SNMPv2c remain intact; however, SNMPv3 has
significant enhancements to administration and security. See the
Works" section on page 47-7
SNMP Security Levels
Level
noAuthNoPriv
noAuthNoPriv
noAuthNoPriv
authNoPriv
authPriv
"Understanding How SNMPv1 and SNMPv2c Work"
for more information on SNMPv3.
Authentication Encryption
Community No
String
Community No
String
Username No
MD5 or SHA No
MD5 or SHA DES
Chapter 47
"Understanding How
for more information on SNMPv2.
"Understanding How SNMPv3
What Happens
Uses a community string
match for authentication.
Uses a community string
match for authentication.
Uses a username match for
authentication.
Provides authentication that is
based on the HMAC-MD5 or
HMAC-SHA algorithms.
Provides authentication that is
based on the HMAC-MD5 or
HMAC-SHA algorithms.
Provides DES 56-bit
encryption in addition to
authentication that is based on
the CBC-DES (DES-56)
standard.
Configuring SNMP
Table 47-2
OL-8978-04