ZyXEL Communications SBG5500-A User Manual page 80

The following table describes the labels in this screen.
Table 19 Configuration > WAN / Internet > xDSL Advanced
LABEL DESCRIPTION
DSL Capabilities
PhyR US Enable or disable PhyR US (upstream) for upstream transmission to the WAN. PhyR US should be
enabled if data being transmitted upstream is sensitive to noise. However, enabling PhyR US can
decrease the US line rate. Enabling or disabling PhyR will require the CPE to retrain. For PhyR to
function, the DSLAM must also support PhyR and have it enabled.
PhyR DS Enable or disable PhyR DS (downstream) for downstream transmission from the WAN. PhyR DS
should be enabled if data being transmitted downstream is sensitive to noise. However,
enabling PhyR DS can decrease the DS line rate. Enabling or disabling PhyR will require the CPE
to retrain. For PhyR to function, the DSLAM must also support PhyR and have it enabled.
Bitswap Enable to allow the SBG to adapt to line changes when you are using G.dmt.
Bit-swapping is a way of keeping the line more stable by constantly monitoring and redistributing
bits between channels.
SRA Enable or disable Seamless Rate Adaption (SRA). Enable to have the SBG automatically adjust
the connection's data rate according to line conditions without interrupting service.
ADSL Modulation
PTM over ADSL Enable to use PTM over ADSL. Since PTM has less overhead than ATM, some ISPs use PTM over
ADSL for better performance.
G.dmt ITU G.992.1 (better known as G.dmt) is an ITU standard for ADSL using discrete multitone
modulation. G.dmt full-rate ADSL expands the usable bandwidth of existing copper telephone
lines, delivering high-speed data communications at rates up to 8 Mbit/s downstream and 1.3
Mbit/s upstream.
G.lite ITU G.992.2 (better known as G.lite) is an ITU standard for ADSL using discrete multitone
modulation. G.lite does not strictly require the use of DSL filters, but like all variants of ADSL
generally functions better with splitters.
T1.413 ANSI T1.413 is a technical standard that defines the requirements for the single asymmetric
digital subscriber line (ADSL) for the interface between the telecommunications network and
the customer installation in terms of their interaction and electrical characteristics.
ADSL2 It optionally extends the capability of basic ADSL in data rates to 12 Mbit/s downstream and,
depending on Annex version, up to 3.5 Mbit/s upstream (with a mandatory capability of ADSL2
transceivers of 8 Mbit/s downstream and 800 kbit/s upstream).
Annex L Annex L is an optional specification in the ITU-T ADSL2 recommendation G.992.3 titled Specific
requirements for a Reach Extended ADSL2 (READSL2) system operating in the frequency band
above POTS, therefore it is often referred to as Reach Extended ADSL2 or READSL2.The main
difference between this specification and commonly deployed Annex A is the maximum
distance that can be used. The power of the lower frequencies used for transmitting data is
boosted up to increase the reach of this signal up to 7 kilometers (23,000 ft).
ADSL2+ ADSL2+ extends the capability of basic ADSL by doubling the number of downstream channels.
The data rates can be as high as 24 Mbit/s downstream and up to 1.4 Mbit/s upstream
depending on the distance from the DSLAM to the customer's premises.
Annex M You can enable Annex M for the SBG to use double upstream mode to increase the maximum
upstream transfer rate.
VDSL Profile VDSL2 profiles differ in the width of the frequency band used to transmit the broadband
signal.Profiles that use a wider frequency band can deliver higher maximum speeds.
8a, 8b, 8c, 8d, The G.993.2 VDSL standard defines a wide range of profiles that can be used in different VDSL
12a, 12b, 17a, deployment settings, such as in a central office, a street cabinet or a building.
US0, 30a
The SBG must comply with at least one profile specified in G.993.2. but compliance with more
than one profile is allowed.
Apply Click Apply to save your changes back to the SBG.
Reset Click this button to return the screen to its last-saved settings.
Chapter 5 WAN/Internet
SBG5500 Series User's Guide
80