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© Virtual Access 2018
GW2020 Series User Manual
Issue: 2.1
Page 370 of 423
36.4
Configuring SNMP interface alias with static SNMP index
A Linux interface index changes dynamically. This is not ideal for SNMP managers that
require static interface indexes to be defined.
The network package interface section allows defining a static SNMP interface alias index
for this interface.
An alias entry is created in the SNMP ifEntry table at index (snmp_alias_i
1000). This entry is a shadow of the real underlying Linux interface corresponding to the
UCI definition. You may use any numbering scheme you wish; the alias values do not
need to be consecutive.
36.4.1
Configuration package used
Package
Sections
network
interface
36.4.2
Configuring SNMP interface alias
To enter and SNMP alias for an interface, select Network->Interfaces->Edit-
>Common Configuration->Advanced Settings.
Enter a small index value for SNMP Alias ifindex that is unique to this interface. To
retrieve SNMP statistics for this interface, the SNMP manager should be configured to
poll (snmp_alias_i 1000). For example, if an interface is configured with an
snmp_alias_ifindex of 11, then the SNMP manager should poll ifIndex=1011. The
ifIndex will remain fixed regardless of how many times the underlying interface is added
or removed.
If the Linux interface associated with the UCI entry is active when the alias index is
polled, the normal ifEntry information for that interface is reported. Otherwise, a dummy
entry is created with the same ifDescr, and its ifOper field set to DOWN.
Note: if you are using SIM roaming, where mobile interfaces are created dynamically,
you need to specify a fixed snmp_alias_ifindex value and a fixed ifName value in the
roaming template. All roaming entries will then map to the same Linux interface name
and underlying device.
Figure 177: The interface SNMP Alias ifindex field advanced settings page