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Unformatted text preview: media. Figure 25.18 Variables in interface table: ifTable.
We can query the host sun for some of these variables for all its interfaces. Wet expect to find three
interfaces, as in Section 3.8, if the SLIP interface is up:
sun % snmpi -a sun
snropi> next ifTable first see what index of first interface is
snmpi> get ifDescr.1 if Type.1 ifMtu.1 if Speed.1 ifPhysAddress.1
snmpi> next ifDescr.1 if Type.1 ifMtu.1 if Speed.1 ifPhysAddress.1
snmpi> next ifDescr.2 ifType.2 ifMtu.2 if Speed.2 ifPhysAddress.2
We first get five variables for the first interface using the get operator, and then get the same five
variables for the second interface using the get-next operator. The last command gets these same
five variables for the third interface, again using the get-next command.
The interface type for the SLIP link is reported as proprietary point-to-point serial, not SLIP. Also,
the speed of the SLIP link is not reported.
It is critical to understand the relationship between the get-next operator and the column-row
ordering. When we say next ifDescr.1 it returns the next row of the table for this variable, not
the next variable in the same row. If tables were stored in a row-column order instead, we wouldn't
be able to step to the next occurrence of a given variable this way. file:///D|/Documents%20and%20Settings/bigini/Doc...omenet2run/tcpip/tcp-ip-illustrated/snmp_sim.htm (16 of 33) [12/09/2001 14.47.40] Chapter 25. SNMP: Simple Network Management Protocol at Group
The address translation group is mandatory for all systems, but was deprecated by MIB-II. Starting
with MIB-II, each network protocol group (e.g...
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