The applTable provides server information. It is a one-dimensional table with one row for the MTA and an additional row for each of the following servers, if enabled: WebMail HTTP, IMAP, POP, SMTP, and SMTP Submit. This table provides version information, uptime, current operational status (up, down, congested), number of current connections, total accumulated connections, and other related data.
Below is an example of data from applTable (mib-188.8.131.52).
applTable: applName.1 = mailsrv-1 MTA on mailsrv-1.west.sesta.com (1) applVersion.1 = 5.1 applUptime.1 = 7322 (2) applOperStatus.1 = up (3) applLastChange.1 = 7422 (2) applInboundAssociations.1 = (5) applOutboundAssociations.1 = (2) applAccumulatedInboundAssociations.1 = 873 applAccumulatedOutboundAssociations.1 = 234 applLastInboundActivity.1 = 1054822 (2) applLastOutboundActivity.1 = 1054222 (2) applRejectedInboundAssociations.1 = 0 (4) applFailedOutboundAssociations.1 = 17 applDescription.1 = Sun Java System Messaging Server 6.1 applName.2 1 = mailsrv-1 HTTP WebMail svr. mailsrv-1.sesta.com (1) ... applName.3 = mailsrv-1 IMAP server on mailsrv-1.west.sesta.com ... applName.4 = mailsrv-1 POP server on mailsrv-1.west.sesta.com ... applName.5 = mailsrv-1 SMTP server on mailsrv-1.west.sesta.com ... applName.6 = mailsrv-1 SMTP Submit server on mailsrv-1.west.sesta.com ...
The application (.appl*) suffixes (.1, .2, etc.) are the row numbers, applIndex. applIndex has the value 1 for the MTA, value 2 for the HTTP server, etc. Thus, in this example, the first row of the table provides data on the MTA, the second on the POP server, etc.
The name after the equal sign is the name of the Messaging Server instance being monitored. In this example, the instance name is mailsrv-1.
These are SNMP TimeStamp values and are the value of sysUpTime at the time of the event. sysUpTime, in turn, is the count of hundredths of seconds since the SNMP master agent was started.
The operational status of the HTTP, IMAP, POP, SMTP, and SMTP Submit servers is determined by actually connecting to them via their configured TCP ports and performing a simple operation using the appropriate protocol (for example, a HEAD request and response for HTTP, a HELO command and response for SMTP, and so on). From this connection attempt, the status—up (1), down (2), or congested (4)—of each server is determined.
Note that these probes appear as normal inbound connections to the servers and contribute to the value of the applAccumulatedInboundAssociations MIB variable for each server.
For the MTA, the operational status is taken to be that of the Job Controller. If the MTA is shown to be up, then the Job Controller is up. If the MTA is shown to be down, then the Job Controller is down. This MTA operational status is independent of the status of the MTA’s Service Dispatcher. The operational status for the MTA only takes on the value of up or down. Although the Job Controller does have a concept of “congested,” it is not indicated in the MTA status.
For the HTTP, IMAP, and POP servers the applRejectedInboundAssociations MIB variable indicates the number of failed login attempts and not the number of rejected inbound connection attempts.
Monitoring server status (applOperStatus) for each of the listed applications is key to monitoring each server.
If it’s been a long time since the MTA last inbound activity as indicated by applLastInboundActivity, then something may be broken preventing connections. If applOperStatus=2 (down), then the monitored service is down. If applOperStatus=1 (up), then the problem may be elsewhere.