I believe that I found one answer to my delima wrt the ifTable not being refreshed when an interface goes away.
I found this excerpt from a Working Group Synopses, by Frank Kastenholz many years back:
"A question regarding the ifTable in dynamic environments was asked. In some environments, the number of interfaces can change without requiring the management system to be re-initialized. This is a problem since the definitions of ifNumber and ifIndex require that the ifTable be a fixed array. The response suggested that the entries in the ifTable remain in existence but be removed from all MIB views."
I must conclude that things haven't changed much. The ifTable does not get updated when an interface (virtual in my case) goes away. Fortunately the ifOperatingStatus does go into the "down" state.
Any further comments or insights are very welcome.
From: Judith Walker [mailto:Judith.Walker@...]
Sent: Friday, November 05, 2010 4:22 PM
Subject: re-reading snmpd.conf file question
I'm finding that when reading the ifTable, some old deleted interfaces are still around. So my snmpwalk of the IfTable is showing data that is out-of-date. (By the way, ethtool does not seem to have this problem.) If I look at the /var/lib/net-snmp/snmpd.conf file, it is correct. In other words, the deleted interface is gone. How can I get the snmpd to re-read the snmp.conf file. The ways mentioned for UCD snmp agents do not seem to work. Can anyone help me?
Kill -HUP 22222 // does not work