Cisco develops own Power over Ethernet standard

Cisco develops own Power over Ethernet standard

Summary: The proprietary 'enhanced Power over Ethernet' standard can power wireless access points designed for the 802.11n draft over the LAN

TOPICS: Networking

Cisco has developed its own proprietary standard to support the latest wireless access points, the company said on Wednesday.

The latest wireless access points, designed for the 802.11n draft, cannot be effectively powered using current switching equipment. 802.11n-based equipment may prove attractive for businesses because it offers up to 300Mbps throughput.

Access points have traditionally been connected via mains electricity, but many new installations are powered over the LAN, using a technique known as Power over Ethernet (PoE).

PoE can only support devices which use less than 15.4W. This includes older access points but, to work effectively, 802.11n-based access points require 18.5W. Businesses wanting to power 802.11n access points have had to disable one of the two radios, which decreases throughput, or else use two switch ports or a separate power injector.

But Cisco now claims to have overcome these problems by supplying 18.5W over the LAN. The power is carried in the spare copper pair which does not carry data.

Although Cisco is a member of the IEEE's PoE standards group — responsible for a global effort to standardise PoE technology — this development has been undertaken separately.

Cisco's go-it-alone effort reflects its history with the technology. Cisco initially developed its own PoE standard, which it called Inline Power, before giving in to competition and adopting standardised PoE in its switches.

The IEEE is developing a separate high-speed standard called PoE Plus, which will support approximately 30W and is expected to be finalised in around 12 months' time. Cisco said it is involved in the IEEE's PoE Plus discussions.

The company said it developed its own high-power technology, which it has named "enhanced PoE", because it had released its own 802.11n-based access point. The Aironet 1250 was released in September 2007.

"The 802.11n standard is out already, so we had to make the switching capability available to customers," said Inbar Lasser-Raab, senior marketing director in Cisco's access routing and switching division.

Lasser-Raab claimed that there would be no interference caused to data by the higher power usage.

Enhanced PoE is included with current Catalyst 3750 and 3560 switches, and will be included on the Catalyst 6500 and 4500 switches from the middle of this year, Cisco said.

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Businesses that currently own those switches can install the feature for free via a software upgrade.

Cisco has also built PoE capability into its 2960 switches, but the feature will incur a substantial price premium.

A 24-port 2960 with eight PoE ports is priced at $1,795 (£920), while the same switch with 24 PoE ports sells for $2,995. Enhanced PoE is not currently available on the 2960.

Cisco has also introduced a small switch which can be powered over the LAN by other switches. The 2960 PD switch is intended for deployment in areas where there is no mains power. It has eight ports, of which one must be given up to bring in the power from the supporting switch. It will be sold at $795.

Lasser-Raab recommended that, as with any PoE deployment, all redundancy options should be considered to avoid a mains outage taking down the network.

Topic: Networking

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  • Cisco should lead the march towards interoperability rather than away

    It is interesting and saddening that Cisco has chosen to go proprietary for powering its "high" power devices, especially at a time, when many PoE vendors who had gone proprietary in their quest for higher power, are now returning back to the IEEE standards to ensure interoperability.

    One of the key goals of the IEEE802.3af standard was to ensure interoperability between any two, standards compliant, devices.

    For over a year, there have been open and inter-operable solutions available that provide up to 30 watts of power.

    I am the CEO of Infomart, which was the first company, globally, to ship a high power PoE splitter under the brand name PoweredEthernet. To ensure interoperability, our PES40 splitters use the existing IEEE802.3af standard with the exception of higher input current limit of up to 720mA, which, by the way, is the current limit proposed for the upcoming IEEE802.3at standard.

    There are quite a few POE injector manufacturers, some major players, like PowerDsine, Phihong, and Panduit, who have developed high power injectors which utilise the same concept of IEEE802.3af compliance, but with up to 720mA of current.

    The models that I am aware of are PowerDsine PD7001G, Phihong POE30U, and Panduit DPOE.

    When paired with these new generation high power single port or multi-port midspans our PES40 splitter delivers up to 30 watts of power.

    Given the influence it wields in the Ethernet space, Cisco should be leading the march towards interoperability, rather than branching out on their own and negatively impacting it. Hopefully Cisco will gain from the lessons of others and return back to interoperability.