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ADSL2+ Tester 5 Performing Measurements
72-0046-03A 61
ADSL2+ can be used to correct this problem by using frequencies below 1.1 MHz from
the central office, and frequencies between 1.1 MHz and 2.2 MHz from the remote
terminal to the customer premise. This will eliminate most of the crosstalk between
the services and preserve data rates on the line from the central office.
If the operator want to know more about ADSL, please refer to ITU-T
G.992.1 (G.DMT), ITU-T G.992.2 (G.lite), ITU-T G.992.3 (G.DMT.bis), ITU-T
G.992.4 (G.lite.bis), ITU-T G.992.5 (ADSL2+), ITU-T G.992 Annex A, Annex
B, Annex C (FBM/DBM), ANSI T1.413 Issue 2, YDN078-1998 for details.
5.2.2
PING
PING is one of the most useful network debugging tools available. It takes its name from a
submarine sonar search - you send a short sound burst and listen for an echo - a ping -
coming back.
In an IP network, PING sends a short data burst - a single packet - and listens for a single
packet in reply. Since this tests the most basic function of an IP network (delivery of single
packet), it's easy to see how you can learn a lot from some pings.
Ping can tell you:
²
Ping places a unique sequence number on each packet it transmits, and reports
which sequence numbers it receives back. Thus, you can determine if packets have
been dropped, duplicated, or reordered.
²
Ping checksums each packet it exchanges. You can detect some forms of damaged
packets.
²
Ping places a timestamp in each packet, which is echoed back and can easily be
used to compute how long each packet exchange took - the Round Trip Time (RTT).
Ping reports other ICMP messages that might otherwise get buried in the system software.
It reports, for example, if a router is declaring the target host unreachable.
5.3
Performing Measurements
This section will introduce how to make measurements with ADSL2+ Tester. Test applications
of Line Parameter, WAN Ping, LAN Ping, Trace and Modem Simulator will be described in
detail.
5.3.1
Line Parameter, WAN PING, TRACE testing
In general, tests shown as below should be made after installation to confirm the quality of
service delivered by ADSL provider.
•
Line Parameter Testing: simulate ATU-R to test ADSL line parameters, such as
Line Bit Rate, SNR Margin, Tx Power, Line Attenuation and Line Standards.
•
ISP PING and Trace.