SNMP MIB2 sensor

The SNMP MIB2 sensor supports Level 2 discovery of SNMP network devices.

In Level 1 discovery profiles, use the SNMP Light sensor with the Stack Scan sensor to improve the accuracy of the discovery. In Level 2 or Level 3 discovery profiles, use the SNMP MIB2 sensor, which discovers additional data for building detailed Level 2 topologies.

The SNMP MIB2 sensor discovers basic SNMP information about the device and other information such as router details, bridge details, IP data (both IPv4 and IPv6), and port data. The SNMP MIB2 sensor calls the Entity MIB sensor and the Bridge SNMP sensor if they are enabled in the discovery profile.

Other sensors are called as the SNMP MIB2 sensor detects the devices that Agile Service Manager supports (for example, the Cisco port sensor and the Cisco VLAN sensor are called if a Cisco device is detected).

The SNMP MIB2 sensor gathers the data that is shown in the following tabs of the Details pane:

General
SNMP Info
IPv6 Router Details
IPv4 Router Details
IP
Interfaces

The SNMP Light sensor and the SNMP MIB2 sensor gather generic information from the following object identifiers (OIDs):

snmpwalk -v 3 -u cmdbadmin -l authPriv -a MD5 -A "" -x DES -X "" 10.199.250.9 
   .1.3.6.1.2.1.1.1.0
SNMPv2-MIB::sysDescr.0 = STRING: Cisco Internetwork Operating System Software
IOS (tm) s72033_rp Software (s72033_rp-JK9SV-M), Version 12.2(17d)SXB11, 
   RELEASE SOFTWARE (fc1)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2005 by cisco Systems, Inc.
Compiled T

snmpwalk -v 3 -u cmdbadmin -l authPriv -a MD5 -A "" -x DES -X "Y1UN9;4b/1tz9l#" 
   10.199.250.9 .1.3.6.1.2.1.1.2.0
SNMPv2-MIB::sysObjectID.0 = OID: SNMPv2-SMI::enterprises.9.1.400

snmpwalk -v 3 -u cmdbadmin -l authPriv -a MD5 -A "" -x DES -X "Y1UN9;4b/1tz9l#" 
   10.199.250.9 .1.3.6.1.2.1.1.4.0
SNMPv2-MIB::sysContact.0 = STRING: Network Support - CH

snmpwalk -v 3 -u cmdbadmin -l authPriv -a MD5 -A "" -x DES -X "" 10.199.250.9 
   .1.3.6.1.2.1.1.5.0
SNMPv2-MIB::sysName.0 = STRING: NC89ZNC01TSL302

snmpwalk -v 3 -u cmdbadmin -l authPriv -a MD5 -A “" -x DES -X "" 10.199.250.9 
   .1.3.6.1.2.1.1.6.0
SNMPv2-MIB::sysLocation.0 = STRING: NC89ACB01

The SNMP MIB2 sensor discovers IPv4 and IPv6 information. Using the IP-MIB and IP-FORWARD-MIB modules (updated in RFC 4293 and RFC 4292), the sensor collects IP interface, forwarding, and routing information. The following OIDs are queried:

1.3.6.1.2.1.4.34	IP-MIB (ipAddressTable)
1.3.6.1.2.1.4.32	IP-MIB (ipAddressPrefixTable)
1.3.6.1.2.1.4.25	IP-MIB (ipv6IpForwarding)
1.3.6.1.2.1.4.1		IP-MIB (ipForwarding)
1.3.6.1.2.1.4.24.7	IP-FORWARD-MIB (inetCidrRouteTable)

ipAddressTable: This table lists the IPv4 and IPv6 addresses.
ipAddressPrefixTable: This table lists the prefix information for all addresses.
ipv6IpForwarding: This flag indicates whether the target device is acting as a router to forward IPv6 packets.
ipForwarding: This flag indicates whether the target device is acting as a router to forward IPv4 packets.
inetCidrRouteTable: This IP routing table lists the routes for both IPv4 and IPv6 interfaces.

If the target device supports the necessary versions of the IP-MIB and IP-FORWARD-MIB modules, the SNMP MIB2 sensor collects all the required information, and discovery completes. If the target device does not support the necessary versions of these modules, the older versions (RFC 2011 and RFC 1213), which gather only IPv4 information, are used, and the following OIDs are queried:

1.3.6.1.2.1.4.20	IP-MIB (ipAddrTable)
1.3.6.1.2.1.4.1		IP-MIB (ipForwarding)
1.3.6.1.2.1.4.21	RFC1213-MIB (ipRouteTable)

In addition, if the target device is a Cisco device, the CISCO-IETF-IP-MIB and CISCO-IETF-IP-FORWARDING-MIB modules are used to gather just the IPv6 information, and the following OIDs are queried:

1.3.6.1.4.1.9.10.86.1.1.2 CISCO-IETF-IP-MIB (cIpAddressTable)
1.3.6.1.4.1.9.10.86.1.1.1 CISCO-IETF-IP-MIB (cIpAddressPfxTable)
1.3.6.1.4.1.9.10.86.1.2.1 CISCO-IETF-IP-MIB (cIpv6Forwarding)
1.3.5.1.4.9.10.85.7 CISCO-IETF-IP-FORWARD-MIB (cInetCidrRouteTable)

Sensor name that is used in the GUI and logs

SnmpMib2Sensor

Limitations

Agile Service Manager currently supports a limited number of network devices. In addition, Agile Service Manager L2 switches are switches and L3 switches are routers. So, L3 switches are displayed as a Router in the Physical Infrastructure tree and in the Topology.

All computer system sensors and the SNMP MIB2 sensor ignore network interfaces that are configured to be down. Agile Service Manager does not populate the net.IpNetwork attribute on the following types of IP interfaces:

loopback, for example, 127.0.0.1, 0:0:0:0:0:0:0:1
link-local, for example, 169.254.1.1, FE80:0:0:0:0:0:0:1
multicast, for example, 224.0.0.1, FF00:0:0:0:0:0:0:1
unspecified, for example, 0.0.0.0, 0:0:0:0:0:0:0:0

Therefore, IP networks are not populated in the Agile Service Manager user interface.

Model objects created

The sensor creates the following model objects:

net.Bridge
net.IpInterface
net.IpRoute
net.IpV4Address
net.IpV6Address
net.IpV4Router
net.IpV6Router
net.L2Interface
sys.UnitaryComputerSystem
sys.OperatingSystem
sys.SnmpSystemGroup