3.7.2 Monitoring DS-1 Lines

There are two options available to a management station that allows it to monitor trunk lines managed by this MIB module. The most high-level option is to monitor the DS-1 Alarm table for changes in the Alarm Type column. Using this method, a management station can determine high-level shifts in line service status. For instance, if a management station observes that a trunk line's alarm type changes from no-alarm to red, the conclusion can be made that a severe fault has been detected for that trunk.

A more detailed way of monitoring trunk line service status is to poll the Line Status column in the DS-1 Trunk Configuration table. Each entry in this column is a bitmap that indicates very specific fault conditions, but does not make any interpretation on what changes in these faults mean. This gives the management station flexibility in making its own policy decisions on what constitutes severe and non-severe alarm conditions.

A management station may use the Line Status trap as a trigger to poll these two columns. This can lead to a more efficient and timely alert to the user when a trunk fault is observed. For example, suppose a management station is configured to poll the Line Status column in the configuration table every five minutes. If the management station does not take advantage of the Line Status trap, a line fault would only be detected on the expiration of every five-minute interval. If the management station is configured to poll when it receives the line status trap, it can take action right away instead of waiting up to five minutes for its polling interval to expire.

Like tables in other media-specific MIBs, the interface number of the DS-1 line indexes the DS-1 MIB tables. These indices correspond to the indices of the same interfaces in the Interfaces Table. This correspondence between interface indices allows management software to quickly find the complete set of general (RFC 1213 MIB-2) and specific (RFC 2495 DS-1) information available for each DS-1 interface.

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