Already UNIX kernels support a vast number of different vendor products, with 802.11G drivers catching up. Unfortunately, the Wired Equivalent Privacy (WEP) used for link-layer security is inadequate for modern requirements and can be compromised easily. The successor security architecture (IEEE 802.11I) should be ready by the end of 2004. Several vendors have already started to implement the draft of this standard.
802.11-based networks are plagued by uninvited guests who either connect for free Internet access or for the purpose of sniffing with roaming adapter cards. Therefore, it is highly recommended to add IPSec (3DES/AES) on top of wireless 802.11 networks for transparent encryption, eventually accompanied by measures such as SSH or SSL. Alternative user-space crypto tunnels can be deployed, too. In addition, strong and encrypted authentication is necessary, because MAC-address-based accounting is of limited use, due to the fact that these addresses can be easily changed/spoofed and are tedious to deploy in a vast network of access points. IEEE 802.1X addresses some of these issues.
802.11 is not the only wireless technology available, just the youngest one. Microwave links, satellite links, and laser links will still be available for a long time. The use of GPRS (General Packet Radio Service) and UMTS (Universal Mobile Telecommunications System) is on the rise.
SDH/SONET
Customers can rent Synchronous Digital Hierarchy/Synchronous Optical Network (SDH/SONET) links from carriers and provide their Layer 2 protocol/encapsulation of choice or directly deploy PoS (Packet over SDH/SONET). These links can be acquired either protected (spare port) or unprotected.
For larger enterprise customers, the carriers usually deploy add/drop multiplexers to deliver fractional STM1/OC3 bandwidth. Depending on the linecards of these multiplexers, channels as small as 56/64 kbps could be extracted/injected (added/dropped in multiplexer lingo). T1/E1 fractions are the most common when looking at the total number of deployed units, most of them at carrier edge facilities. Due to the increasing bandwidth needs of larger enterprises, such trunks are normally sold as multiples of full T1/E1 rates. In carrier backbones, state-of-the art photonic networks based on optical cross-connects and dense wavelength-division multiplexing (DWDM) technology transport aggregated traffic of multiple 10 to 100 Gbps
Powerline Communications
Deployment of powerline systems (low-voltage communication) for WAN access requires new equipment at every electrical substation of the energy supplier. The subscriber must be within the rather short and tight distance restrictions of a few hundred meters. Powerline intrinsically is a shared-access technology as well and delivers an Ethernet/USB interface as a demarcation point.
Powerline itself, although initially difficult to deploy, offers the opportunity of new and exciting services: LAN-only powerline in-house cabling, energy management, and remote control of electrical home equipment, just to mention a few.
NOTE
Deployment of T1/E1 symmetrical bandwidth is common. For a technology overview, go to http://www.ipcf.org/powerlineintro.html.
Ethernet to the Home/Premises
With the advances and widespread availability of long- and ultra-long-reach photonic networks, carriers can now provide 10/100/1000-Mbps Ethernet or shaped bandwidths to metropolitan customers, delivering Ethernet demarcation points (optical or copper ports). These services are offered transparently or via virtual LAN (VLAN) or Multiprotocol Label Switching (MPLS) architectures.
Cisco Long-Reach Ethernet (LRE)
Cisco LRE delivers speeds of 5 Mbps to 15 Mbps over legacy category 1/2/3 wiring over several thousand meters. LRE is an extension to the IEEE 802.3 Ethernet standard for single-pair wiring. This requires special switch ports on one end and CPE devices for the office ports on the other end to simultaneously use Plain Old Telephone System (POTS) and Integrated Services Digital Network (ISDN). This is achieved via a sophisticated modulation approach: quadrature amplitude modulation (QAM). Cisco provides a solution that consists of switches, CPE devices, and a POTS splitter for simultaneous use of existing private branch exchange (PBX) equipment.
NOTE
The LRE architecture can coexist with DSL on the same wire bundle facilitating frequency-division multiplexing (FDM).
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