In computer networking, network address translation (NAT) is the process of modifying network address information in datagram (IP) packet headers while in transit across a traffic routing device for the purpose of remapping one IP address space into another.
Most often today, NAT is used in conjunction with network masquerading (or IP masquerading) which is a technique that hides an entire IP address space, usually consisting of private network IP addresses, behind a single IP address in another, often public address space. This mechanism is implemented in a routing device that uses stateful translation tables to map the "hidden" addresses into a single IP address and then readdresses the outgoing Internet Protocol (IP) packets on exit so that they appear to originate from the router. In the reverse communications path, responses are mapped back to the originating IP address using the rules ("state") stored in the translation tables. The translation table rules established in this fashion are flushed after a short period without new traffic refreshing their state.
As described, the method enables communication through the router only when the conversation originates in the masqueraded network, since this establishes the translation tables. For example, a web browser in the masqueraded network can browse a website outside, but a web browser outside could not browse a web site in the masqueraded network. However, most NAT devices today allow the network administrator to configure translation table entries for permanent use. This feature is often referred to as "static NAT" or port forwarding and allows traffic originating in the 'outside' network to reach designated hosts in the masqueraded network.
Thursday, June 24, 2010
Sunday, March 28, 2010
Gobi™ - Global Mobile Internet Technology
The World is Your Hotspot™
Of all the things that your notebook computer does, connecting to the Internet – simply and reliably – is among the most important. Gobi™ is the first embedded mobile wireless solution designed to put an end to connectivity limitations. With Gobi, the notebook computer becomes the unifying agent between the different high speed wireless networking technologies deployed around the world and that means freedom from having to locate hotspots, more choice in carrier networks, and, ultimately, freedom to Gobi where you want without fear of losing connectivity – your lifeline to your world.
Would you like your notebook to provide a choice of wireless network carriers and global connectivity possibilities? No matter where you travel?
Notebooks featuring the multi-mode Gobi solution can take advantage of the high-speed mobile Internet services offered by leading network operators in virtually all parts of the world, as well as GPS. The Gobi solution is meeting the demand from leading notebook manufacturers for worldwide connectivity capabilities beyond Wi-Fi and is being certified to operate on 3G networks worldwide. What does this mean for you? With your Gobi notebook you'll have mobile Internet access wherever you can make a mobile phone call. Regardless of where you go, you'll have global connectivity – even international travel is no longer a problem with Gobi. Searching for Wi-Fi hotspots will be a thing of the past when you have Gobi built in to your notebook. And, Gobi enables popular location-based services delivered via GPS, such as driving directions, asset tracking, anti-theft, and enhanced commerce when you're on the road.
Benefits
- Removes complex technology decision process – end users can use their favorite carrier to connect wherever life takes them
- Provides global connectivity for the end user
- Simplifies notebook supply chain logistics with a single global SKU that supports many different geographies, technologies, and carriers
- Optimizes battery, radio, and throughput performance
Technical Features
- Integrated GPS functionality that allows deployment of location-based services while concurrently operating with other data modes
- Integrated mobile reception diversity for much improved performance and better, faster connections
- Integrated power management system
- Major RF bands and GPS functionality all on one chipset
Sunday, February 28, 2010
High-Speed Packet Access (HSPA+ )
HSPA+, also known as Evolved High-Speed Packet Access is a wireless broadband standard defined in 3GPP release 7.
HSPA+ provides HSPA data rates up to 56 Mbit/s on the downlink and 22 Mbit/s on the uplink withMIMO technologies and higher order modulation (64QAM). MIMO on CDMA based systems acts like virtual sectors to give extra capacity closer to the mast. The 56Mbit/s and 22Mbit/s represent theoretical peak sector speeds. The actual speed for a user will be lower. At cell edge and even at half the distance to the cell edge there may only be slight increase compared with 14.4 Mbit/s HSDPA unless a wider channel than 5 MHz is used. Future revisions of HSPA+ support up to 168Mbps using multiple carriers[1].
HSPA+ also introduces an optional all-IP architecture for the network where base stations are directly connected to IP based backhaul and then to the ISP's edge routers. The technology also delivers significant battery life improvements and dramatically quicker wake-from-idle time - delivering a true always-on connection. HSPA+ should not be confused with LTE, which uses a new air interface.
Mobile telephony and mobile telecommunications standards
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An all-IP architecture is an option within HSPA+. Base stations connect to the network via standard gigabit Ethernet to the ISP's edge routers connected to the internet or other ISP via peering arrangements. This makes the network faster, cheaper to deploy and operate.
However the legacy architecture is still possible with the Evolved HSPA. This 'flat architecture' communicates 'user plane' IP directly from the base station to the GGSN IP router system, using any available link technology. It is defined in 3GPP TR25.999. User IP data bypasses the Radio Network Controller (RNC) and the SGSN of the previous 3GPP UMTS architecture versions. This is a major step towards the 3GPP Long Term Evolution (LTE) flat architecture as defined in the 3GPP standard Rel-8. In essence the flat architecture turns the cellular base station into an IP router. It connects to the Internet with cost effective modern IP link layer technologies like Ethernet, and for user plane data it is not tied to the SONET/SDH infrastructure or T1/E1 lines anymore.
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