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Encyclopedia > AppleTalk Remote Access

AppleTalk Remote Access, or ARA, was a protocol stack that allowed AppleTalk to be run over modems. It became a fairly major product for Apple Computer in the early to mid-1990s when their first portable and laptop computers were available (and very popular). ARA slowly disappeared in the late 1990s when TCP/IP took over the vast majority of networking needs, notably remote access.


Most networking protocols have strong "layering" that separates the varies jobs inside the protocol to different pieces of software. This allows them to be run on top of any hardware by replacing the lowest level software, the hardware drivers. For instance, IP can be made to run on a variety of Ethernet cards or even TokenRing with little effort. For slower speeds, like on modems, things become somewhat more difficult, as the protocols often have "invisible" assumptions about timing and performance that make it inefficient with very limited bandwidth.


AppleTalk included a number of features that made this even more difficult. In particular AppleTalk had a number of internal tasks for discovery and naming that ran all the time and made the protocol "chatty". This added to the bandwidth problems, making it even less efficient in this case.


Thus ARA was considerably more complex than similar solutions for IP, replacing many parts of the AppleTalk stack and seriously modifying others. As a result ARA was quite large, larger than the basic AppleTalk stack, and somewhat memory hungry. It was also slow, a problem it shared with IP at similar speeds.


Nevetheless ARA was the only game in town, and also shared the typical Apple properties of being easy to install, set up and run. It became a fairly profitable product on its own, and was sold widely in stores. However the introduction of SLIP and the increased use of IP on the Macintosh led to some infighting within Apple as the profits from ARA were cut into. This led Apple to place their IP remote access software in ARA as well, although this had the side-effect of making various freeware implementations much more popular.


ARA remained an important, if somewhat less so, product for Apple into the late 1990s. In Mac OS X it is no longer required, as Apple has migrated the vast majority of their networking software to IP, and includes remote access software for free.




  Results from FactBites:
 
RFC 1504 (rfc1504) - Appletalk Update-Based Routing Protocol: Enhanced App (17756 words)
If the length of an AppleTalk data packet in bytes is greater than that of the data field of a foreign-protocol packet, a forwarding exterior router must fragment the AppleTalk data packet into multiple foreign-protocol packets, then forward these packets to their destination.
AppleTalk networking software running on a node on a hidden network lists all of the AppleTalk zone names exported by exterior routers connected to a tunnel, but may list the names of only some or none of the devices in those zones.
The exterior router maps UIs corresponding to network numbers for remote networks-that is, networks connected to other exterior routers on the tunnel-that are in packets received through the tunneling port to network numbers in the remapping range configured for the local internet, as shown in Figure 4-2.
  More results at FactBites »


 

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