What are Ad Hoc and Infrastructure Networks?
LAVA’s wireless serial device servers (WiFi ESLs) can operate in Ad Hoc or Infrastructure modes. These two modes are fundamentally different, each with their own advantages and disadvantages.
Ad Hoc Networks
The Latin expression “ad hoc” translates into English as “for this,” a translation that loosely suggests what ad hoc networks are: networks set up for a single simple purpose. In their simplest form, Ad Hoc networks are peer-to-peer connections between two wireless devices capable of operating in Ad Hoc mode. The two devices have a direct wireless connection to each other, with no intervening wireless devices (or “infrastructure”) such as wireless access points or routers.
Additionally, multiple Ad Hoc devices sharing the same SSID (“Service Set Identifier”) can be on the same Ad Hoc network, extending the concept from a one-to-one network to a multi-node system of connections.
Ad Hoc networks can be set up simply and easily with no need for a pre-existing wireless network, or for additional network hardware beyond the nodes in the network itself. Ad Hoc networks offer low cost networking as well. Disadvantages of Ad Hoc networks include generally shorter working ranges than those of more highly-powered Infrastructure networks, decreasing performance as the number of devices in an Ad Hoc network increases, and no bridge to wired networks. Another disadvantage of conventional Ad Hoc networks is that they do not implement the strongest levels of security now available.
Infrastructure networks are collections of wireless devices attached to an intermediate piece of network infrastructure, typically an access point, router, or PC running access point software. A WiFi ESL in Infrastructure mode becomes a wireless part of a larger Local Area Network (LAN).
Advantages of Infrastructure networks include greater power and distance than most Ad Hoc networks, greater scalability and stability, and better security. These advantages come at the cost of greater expense to set up, and of reduced flexibility.
What does this mean for wireless serial device servers? For one thing, it means that a WiFi ESL in Ad Hoc mode is an extremely simple and effective means of adding a serial port to a laptop, with no need for USB-to-serial, hard wired Ethernet-to-serial connection, or a wireless router. For another, in Infrastructure mode, WiFi ESLs offer all the advantages of wired networked serial ports: simplicity, reliability, and configurability.
LAVA has expanded its Ether-Serial Link serial device server line with wireless Ethernet variants of its ESL 1-232-DB9, ESL 2-232-DB9, ESL 1-232-RJ45, and ESL 2-232-RJ45 units.
These new wireless serial device servers support 802.11a or 802.11b+g modes, with choices of WEP 64, WEP 128, WPA (TKIP), or WPA2 (AES) encryption. They retain all the functionality of the standard LAVA Ether-Serial Links, with DHCP/manual IP address configuration, intuitive installation and configuration, full-throughput non-blocking serial ports at 115.2 kbps, and upgradeable firmware.
The serial ports are configurable in a variety of modes: Windows-implemented ports (driver mode), raw TCP client connections, raw TCP server connections, raw data connections (client + server), Ethernet modems (accepting Hayes-compatible command strings), or RFC 2217 controlled ports (serial control over Telnet).
The wireless Ether-Serial Links include full Windows support from Windows XP through Windows 7, as well as Linux support. In raw modes they are operating system independent.
They include a power supply, the LAVA Ether-Link Manager application (Windows), and of course, the LAVA Lifetime Warranty.
Shergroup Textiles runs its DOS-based accounting system “RealWorld” inside an emulator on a SCO Unix server. This accounting package has a virtual serial interface, but no physical serial port exists on the server. Users at Shergroup can access this accounting package through dedicated terminals. One exception exists however: a user on a Windows system, who needs to run another Windows-based package as well.
Shergroup has developed a solution that provides the best of both worlds for this user: on that person’s system they have installed another DOS emulator that talks to a LAVA single serial port card (the LAVA SSerial-PCI). That card is in turn connected to a LAVA Ether-Serial Link serial device server, which in turn is connected to the UNIX server.
In effect, a serial tunnel runs between the two emulators, making it possible for the user on the Windows system to connect to the DOS emulator on the UNIX system.
You’re probably aware that all LAVA boards are covered by the LAVA Lifetime Warranty. We don’t beat around the bush — the bottom line is that if your LAVA card fails to perform in its intended use, we will fix or replace it.
What makes us confident enough to offer this warranty? It’s simple: we engineer and manufacture LAVA boards ourselves, so we know our products inside out. But more than that, we test every LAVA board individually to ensure that it is working, before it ships.
That final statement means a lot, and is worth a close look. It is not actually enough to know a design works. The fact is that “stuff” happens, and not every component is identical. The overwhelming majority of finished cards coming out of the solder machine will work, but there will be some that won’t and at the end of it all the only way to know that a given card works is to test it.
It’s almost too obvious to say such a thing, but the reality is that many manufacturers test only a sample of products in a production lot, on the assumption that a given failure rate is acceptable, or maybe thinking that failures won’t happen. That belief might be good enough for them, but is it good enough for you? What will it cost you to visit a customer site to troubleshoot a hardware failure?
Life isn’t perfect, but LAVA tries to come close. And remember, we also have unlimited live free technical support and a no-hassle return policy.