Specifications

4-17
Cisco AS5x00 Case Study for Basic IP Modem Services
11/24/1999
Section 4 Verifying Modem Performance
Initiating a Modem Loopback Test Call
Table 4-4 describes the significant parameters in the previous example. For a complete command
reference description, refer to the following URL:
http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/12cgcr/dial_r/drprt1/drmodmgt.ht
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Table 4-4 Operational Parameter Descriptions for a Loopback Test Call
Parameter Description
Parameter #1 Connect Protocol: LAP-M
LapM is the connection protocol.
Parameter #6 Total Retrains: 0
The modem has no retrain counts.
Parameter #8 Connected Standard: V.34+
The modem connects at V.34.
Parameter #9 TX,RX Bit Rate: 33600, 33600
The receive and transmit bit rate is 33600 bps,
which is the fastest possible V.34 speed. You will
never attain V.90 with this test. MICA-to-MICA
calls default to V.34 modulation. V.90 requires
one analog modem.
Parameter #11 TX,RX Symbol Rate: 3429, 3429
The transmit and receive symbol rate is 3429.
To achieve 33600 bps, you must have a 3429 Hz
passband.
Parameter #21 Signal Noise Ratio: 41 dB
The signal to noise ratio is 41 dB.
Parameter #26 Far End Echo Level: -52 dBm
Use this field to detect a near-end
digital-to-analog conversion. For this test, an
acceptable value is less than -55 dB.
If you see a high level of far end echo (-55 or
higher), a digital-to-analog conversion most
likely exists between the NAS and the switch.
This conversion severely impairs modem
performance.
Parameter #30 Characters transmitted,
received: 70966, 80
The number of characters transmitted and
received by the modem.