Discussion

juniperMIB, which is the top node of the Juniper enterprise-specific portion of the
MIBtree. Both these OIDs are absolute references because they start at the root
node, which is indicated by the dot (.) before the first number (.1.3.1.4.1.2636
rather than 1.3.1.4.1.2636). In NMS and JUNOS software, you can refer to the
OIDs by absolute OID or by name; the names are generally easier to remember and
type. Figure 4-1 illustrates a portion of the MIBtree that leads to these OIDs and
shows that each node has both text and a number to identify it.
+-iso(1)
+--org(3)
+--dod(6)
+--internet(1)
| +--directory(1)
| +--mgmt(2)
| +--mib-2(1)
| +--system(1)
| sysDescr(1)
| sysObjectID(2)
| sysUpTime(3)
| sysContact(4)
| sysName(5)
| sysLocation(6)
| sysServices(7)
... |
+-private(4)
+-enterprises(1)
+-juniperMIB(2636)
+-jnxProducts(1)
+-jnxServices(2)
+-jnxMIBs(3)
+-jnxBoxAnatomy(1)
+-mpls(2)
+-ifJnx(32)
+-jnxAlarms(4)
+-jnxFirewalls(5)
+-mpls(2)
...
Figure 4-1. MIB tree with OIDs
The SNMP manager targets specific nodes in the MIBtree when gathering status and
statistics about the agent systems.
While the OID relates to the location in the MIBtree, it is the instance that relates to
the data object or value at that location. For example, the OID .1.3.6.1.2.1.1.4 corresponds
to sysContact, and .1.3.6.1.2.1.1.4.0 corresponds to the value in that
field, such as “Fred Flintstone.”
MIBobjects can be defined as being read-only, meaning that the SNMP manager can
retrieve its information only with an SNMP Get command (or with Get derivatives
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Introduction | 131