VDSL and GSHDSL
Very High-Speed Digital Subscriber Line (VDSL) is a digital subscriber line (DSL) technology that provides high-speed data transmission over existing copper telephone wires. It is an advanced version of earlier DSL standards like ADSL, offering significantly faster speeds by utilizing higher frequency ranges
Symmetric High-Speed Digital Subscriber Line (G.SHDSL) is a data communications technology designed for symmetric high-speed data transmission over copper twisted pairs. While the query mentioned G.HDSL, G.SHDSL (standardized as ITU-T G.991.2) is the more modern and widely adopted international standard for symmetric DSL. G.HDSL (G.991.1) is an older standard.
Key characteristics of VDSL
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Speed: VDSL can offer speeds up to 52 Mbit/s downstream and 16 Mbit/s upstream. Its successor, VDSL2 (ITU-T G.993.2), can provide data rates exceeding 100 Mbit/s simultaneously in both upstream and downstream directions, and VDSL2+ can reach 300+ Mbit/s.
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Technology: It uses frequencies up to 12 MHz (VDSL) or up to 30 MHz (VDSL2) to achieve these higher speeds.
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Applications: VDSL is capable of supporting applications such as high-definition television (HDTV), voice over IP (VoIP), and general high-speed internet access over a single connection.
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Distance Sensitivity: The performance of VDSL degrades as the distance from the service provider's equipment increases.
For related information, see VDSL Commands.
Key characteristics of G.SHDSL
G.SHDSL is an international standard that allows devices to send and receive high-speed symmetrical data streams over a single pair of copper wires. This section provides information about the Cisco G.SHDSL EFM/ATM NIM and provides guidelines for configuring G.SHDSL in SD-WAN mode.
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Symmetry: Unlike asymmetric DSL (ADSL), G.SHDSL provides symmetrical transmit and receive data rates, meaning the upload and download speeds are equal.
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Speed: It offers symmetric rates typically ranging from 192 kbit/s to 15296 kbit/s on a single twisted pair.
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Applications: G.SHDSL is often used for high-speed commercial broadband services, enabling applications that require significant data transfer in both directions, such as LAN remote access, web hosting, and combining multiple voice and data channels.
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Compatibility: It is compatible with other DSL technologies and can extend transmission distances while maintaining high data rates.
For related information, see Configuring Cisco G.SHDSL HWICs in Cisco Access Routers and VDSL Commands.
VDSL configuration guidelines
This table provides usage information and guidelines for configuring asymmetric DSL (ADSL2/2+) and VDSL for supported Integrated Services Router Network Interface Modules (ISR NIMs) in SD-WAN mode. VDSL2 and ADSL2/2+ provide highly reliable WAN connections for remote sites.
|
Function |
Command |
Guidelines |
|---|---|---|
|
Configure operating mode |
Device# configure terminal Device(config)# controller VDSL slot/subslot/port Device(config)# operating mode auto |
To switch from operating mode auto adsl1 (adsl2+/ or vdsl2) to operating mode auto ads2+ (adsl1 or vdsl2), switch to operating mode auto first. Before you change the operating mode, ensure that line-mode is changed to line-mode single-wire line 0. |
|
Enable DSL on a line |
Device(config)# line-mode single-wire line line-number |
This command is supported only on DSL NIM-VAB-A. |
|
Enable bonding |
Device(config)# line-mode bonding |
This command is supported only on DSL NIM-VAB-A. |
|
Load firmware on a device |
Device# configure terminal Device(config)# controller VDSL slot / subslot / port Device(config-controller)# firmware phy filename filename |
The Cisco Catalyst SD-WAN CLI template does not support specifying the file location. Prepend the file name with flash: or with bootflash:, depending on its location. |
|
Enable or disable SRA |
Device(config-controller)# sra |
The Cisco Catalyst SD-WAN CLI template does not support the sra line number command. In line-mode bonding, sra enables sra on both lines and no sra disables sra on both lines. |
|
Enable or disable bitswap |
Device(config-controller)# bitswap |
The Cisco Catalyst SD-WAN CLI template does not support the bitswap line number command. In line-mode bonding, bitswap enables bitswap on both lines and no bitswap disables bitswap on both lines. |
|
Enable modem features |
Device(config-controller)# modem keyword |
– |
|
Display a description of a controller |
Device(config-controller)# description string |
– |
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Enable dual ended line testing |
Device(config-controller)# diagnostics DELT |
– |
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Modify the file in which the training log is stored |
Device(config-controller)# training log filename flash: filename |
The Cisco Catalyst SD-WAN CLI template does not support specifying the file location. Prepend the file name with flash: or with bootflash: , depending where the file should be stored. |
|
Enable sync mode |
Device(config-controller)# sync mode mode |
To switch from one sync mode to another, delete the existing sync mode, then configure the new one. |
|
Enable sync interval |
Device(config-controller)# sync interval seconds |
– |
GSHDSL configuration guidelines
This table provides usage information and guidelines that apply when you configure the Cisco G.SHDSL EFM/ATM in CPE or CO mode.
|
Function |
Command |
Guidelines |
|---|---|---|
|
Configure a device with the dsl-group auto command |
Device(config-controller)# dsl-group auto |
Use customer premises equipment (CPE) mode when configuring a device with the dsl-group auto command. If you use this command in Central Office (CO) mode, the configuration does not take effect. |
| Add or delete a link |
— |
The efm-grp command is not supported. To add or delete a link to a dsl-group, delete the dsl-group, then create a new dsl-group. |
|
Load firmware on a device |
Device(config-controller)# firmware phy filename location |
File name location options are not supported when using the firmware phy command. Prepend the file name with flash: or with bootflash: , depending on the location. |
|
Create or delete an annex |
Device(config-controller-dsl-group)# no shdsl annex Device(config-controller-dsl-group)# no shdsl rate rate |
To avoid Cisco IOS and Cisco Catalyst SD-WAN configuration from going out of sync when you create or delete an annex, create or delete the rate in the same transaction. |
|
Enable SHDSL to use enhanced mode |
(config-controller-dsl-group)# shdsl 4-wire mode enhanced |
To enable SHDSL to use the enhanced mode in a 2-pair digital subscriber line (DSL) group, use the shdsl 4-wire mode enhanced command in configuration controller DSL group mode. |
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Ignore CRC errors |
(config-controller-dsl-group)# ignore seconds |
To configure a device to ignore CRC errors, use the ignore command. Replace timeout with a value from 0 through 60, which indicates the number of seconds that the device ignores CRC errors that do not resolve before the device terminates an action. |
|
Shutdown a DSL group |
(config-controller-dsl-group)# shutdown |
To shut down a DSL group, use the shutdown command. |
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