
12. Port Management - non-iMAP Devices Dual End Line Testing (DELT)
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AlliedView NMS Administration Guide
FIGURE 12-6 GenBand Line Report
12.3 Dual End Line Testing (DELT)
DELT provides information about the quality of the link between the ADSL card and the modem by collecting upstream and
downstream values for attainable rate, line attenuation, signal attenuation, signal-to-noise margin, power spectrum density,
and aggregate transmitted power. DELT diagnostics are conducted over a low bit rate channel between the iMAP and the
CPE and can therefore be executed in extremely degraded cases where the ADSL link cannot train up.
The data collected is based on recommendations of ITU G.997.1 section 7.5.
In addition to line-level attributes, DELT tests also collect signaling information on a sub-carrier basis. For ADSL, there are
512 sub-carriers per line. The sub-carrier data can be graphically displayed to show the characteristics of the line. The
graph, in conjunction with signaling templates, can reveal the source or sources of line interference.
For provisioning, note the following:
• This feature works with the xDSL family (ADSL24A, ADSL24B, ADSL48A, ADSL48B, ADSL24SA, VDSL, PAC24A,
ADSL24AE) of cards.
• DELT results are only available if the service module and modem are configured to support one of the ADSL2 modes.
• Not all ADSL2 and ADSL2+ modems support DELT. Running DELT diagnostics on a modem that is not DELT capable
will result in a DELT test failure.Since DELT is relatively new capability, inter operability issues exist with some CPE
devices. These issues can cause DELT diagnostics to fail, or in some cases, cause DELT to report incorrect results. Allied
Telesis will publish a list of CPE (hardware and software versions) that have been verified for proper DELT operation.
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