FEATURE | ISPs around Australia are actively working on rolling out the next-generation DSL technologies: ADSL2 and ADSL2+, which will provide greater range and higher speeds than the current DSL standard.

Despite their similar names, the two ITU standards are quite different. ADSL2 aims to improve the performance and interoperability of the original ADSL specification with longer range and slightly enhanced speed. ADSL2+ offers twice the speed of ADSL1 and ADSL2, but also uses twice the phone-line bandwidth.

In the article continuation:

• ADSL2 and ADSL2+ compared
• ISPs working on rollouts
• Will your modem need to be upgraded?
• Can you get ADSL2/2+?

ADSL2 and ADSL2+ compared

ADSL2 has slightly longer reach than the original ADSL standard – between 200M and 750M extra, depending on who you believe. It also has marginally better speed, and some other advantages like better line diagnostics inbuilt into modems and power-saving modes for modems when they're not transmitting.

Importantly, it uses the same spectral mask (wavelength) as ADSL1, meaning there is no technical reason why it can't be active today over existing phone lines.

However, ISPs are hesitant to run the standard without the formal approval of the industry's self-regulating body, the Australian Communications Industry Forum (ACIF). According to Internode CEO Simon Hackett, "the only apparent barrier to our turning on ADSL2 in street copper today is ACIF approval of the ADSL2 deployment mode. This is essentially a rubber-stamp exercise for ADSL2 due to the spectral compatibility with ADSL1 noted above."

ADSL2+ is a totally different specification to ADSL2. It doubles the downstream bandwidth on short distances. People living within 1.5km of an exchange will get "up to" 24Mbit/s, a scorching speed that would trump even cable internet, which has previously been the best choice for fast broadband. However, outside a 1.5KM radius, most users will get at best 12Mbit/s, and speed declines rapidly the further away from an exchange the end user is.

An interesting optional mode in ADSL2+ doubles the upstream bandwidth, which (if utilised) will prove very popular amongst users who host servers on their connections. It could be deployed over Australian lines, but, once again, is also being held back by approval from the ACIF.

Because ADSL2+ uses twice the line bandwidth of ADSL1 and ADSL2 (up from the original standard's 1.1MHz to 2.2MHz), there is a legitimate case for proper testing to ensure it doesn't interfere with other services run over phone lines. However, as some ISPs have pointed out, it's already running without problems in some parts of the world.

It has been reported that ACIF is aiming for certification of both standards by the end of the year.

ISPs working on rollouts

The signs are that both ADSL2 and ADSL2+ will be widely supported in Australia. Whirlpool spoke to ISPs and hardware vendors, and almost every company interviewed said they expected services to be online within 6 - 12 months.

• Gold Coast ISP OntheNet says it will offer ADSL2 to the 120,000 residents it currently covers with its own DSLAMs as soon as it the standard is approved by the ACIF.

• Internode has ADSL2 running right now in its test lab, and will have ADSL2+ working within two months following a firmware upgrade from its DSLAM suppliers..

• iiNet intends to roll out ADSL2/2+ as soon as it is ratified by the ACIF. The 'iiSlams' being installed into 100 exchanges around the country are already ADSL2/2+ compatible on a hardware level, and will simply require a firmware upgrade. iiNet's Michael Malone says he fully intends to introduce higher speed services for home users. He is quoted in The Australian as saying that 20Mbit/s speeds are his aim.

• ISP heavyweight iPrimus has made its intention to roll-out ADSL2 and ADSL2+ services clear. According to an AAP report, it has already enabled 40 exchanges, and by the end of this year will have enabled another 150 exchanges. It will roll-out another 150 exchanges next year, bringing the total number of ADSL2/ADSL2+ exchanges to 340.

• Telstra refused to comment, but previously told APC Magazine it was "actively pursuing" the rollout of ADSL2/2+ within its network. Its DSL infrastructure is based around a lot of Alcatel and a small amount of new NEC hardware. The Alcatel hardware can be upgraded to ADSL2/2+ compatibility if 'line cards' are replaced – likely to be a costly exercise across the whole network. The NEC equipment already has ADSL2/2+ compatibility built in. Telstra Wholesale has, however, told its ISP customers that while ADSL2 and 2+ will provide distance enhancements, it doesn't have any immediate plans to offer a higher speed DSL product at wholesale.

• OptusNet is also widely expected to announce a broad DSLAM rollout in coming months, which would undoubtedly use ADSL2/2+ compatible equipment.

The promise of faster speeds and longer ranges are useless to users whose equipment is incompatible with ADSL2/2+. Unless users have purchased their ADSL equipment in the last 6 - 8 months, their equipment will be the equivalent of a 14.4K analog modem connecting to a 56K dial-up provider.

A number of leading manufacturers were contacted for comment, but their responses were mixed.

• D-Link didn't reply to an invitation to comment. However, its DSL-G604T Router is apparently ADSL2/2+ capable via a firmware upgrade.

• Netcomm said that "It is not possible to upgrade most existing products to be ADSL2/2+ compliant". (ADSL2/2+ requires a capable chipset, so ADSL1 chipsets can never be made to work at ADSL2/2+ speeds.) However, Netcomm's just-announced NB5 ADSL Modem/Router is claimed to be "the first Telstra-approved ADSL2-capable modem router on the market".

• A Linksys spokesperson said that none of the current Linksys product line-up is ADSL2/2+ compatible. However, they are expecting to release a new line of products in the next 4 - 8 months which would support the new standards.

• Netgear said that a number of its products are ADSL2/2+ compatible already, and they are working on firmware upgrades for the rest of their currently on-sale product range. Current compatible products include the DG632, DG834v1 DG834v2, DG834Gv1, DG834Gv2. All new products released from Netgear will be ADSL2/2+ compatible, and will be able to take advantage of future technologies such as Video on Demand and Voice Over DSL.

• Billion distributor Raaj Menon said "The products currently DSL2+ ready are Billion 7402 and 7402W. The 7500G is ADSL 2 compatible but not 2+". Billion is intending to offer firmware upgrades to some models to make them ADSL2/2+ capable, but some products will be discontinued and replaced with newer models. All future models released by Billion will support both standards.

As with all broadband technologies, the major problem that ISPs will face will be hoards of users disappointed that they can't immediately get ADSL2/2+. Some industry representatives are predicting a worsened case of the "broadband haves and have nots", with some users able to get the super fast ADSL2+ speeds while others struggle to get 12Mbps.

This will be another headache for ISPs - in addition to complaints from users about pair gain and RIMs, they will have to deal with users unable to get full ADSL2+ speeds on their connections.

Regardless of the difficulties, ADSL2/2+ will bring Australian internet users closer to 'true broadband speeds' within the next year. This can only be welcome news considering Australia has to date had to put up with relatively slow 1.5Mbit/s DSL connections, or opt for one of only two cable networks with patchy coverage.

Links:

• Australian Communications Industry Forum
• ADSL2 and ADSL2+: the new standards  (Aware, Inc (White paper, 110KB PDF))