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Macintosh NBPLookup badUnitErr conditionsDate Written: 11/14/90 Last reviewed: 2/8/91
Why am I getting a
You're probably getting the See the Macintosh Technical Note "Opening AppleTalk" for a description of how to open the AppleTalk drivers. AppleTalk 56 NBP reply packet entity field checksDate Written: 6/14/91 Last reviewed: 6/14/93 As stated in Inside AppleTalk, each entity field in an NBP reply packet can be a maximum of 32 characters. In previous versions of AppleTalk, no range checking was done on entity field lengths, and often names that were too long were used, which eventually caused a crash somewhere else in the protocol stack.
Likewise, a null character in the object field of an entity has never been OK;
it just happened to work because no range checking was done. (The only place
that a null can legally be used in an NBP tuple is in the zone name field of an
NBP Now, under Appletalk 56, a range check is done on each entity field to ensure that the length is legal (1<=length<=32). When it finds a packet that contains a "corrupt" entity name, that packet is discarded. Name Binding Protocol (NBP) interval and count fieldsDate Written: 9/13/91 Last reviewed: 10/8/91
Is there a limit on the values set in the Name Binding Protocol (NBP) interval
and count fields when used with Since the interval and count parameters for NBP calls are both 1-byte, the values used are limited to the range of 0-255 ($00-$FF). Here's what the values do:
Three things can happen to make the
The AppleTalk PLookupName interval and retry valuesDate Written: 1/6/92 Last reviewed: 1/27/92
What are recommended values for retry interval and retry count when using the
AppleTalk NBP call You might want to start with the NBP retry interval and retry count values Apple uses for its Chooser PRER and RDEV device resource files. The Chooser grabs these values from the PRER's or RDEV's GNRL resource -4096:
Apple's engineering teams found these values to work well in most situations. The count value should be based on how likely it is for the device to miss NBP lookup requests. For example, the AppleTalk ImageWriter has a dedicated processor on the LocalTalk option card just to handle AppleTalk, so its count value is low; most Macintosh models and LaserWriter printers depend on their 680x0 processor to handle AppleTalk along with everything else in the system (the Macintosh IIfx and Macintosh Quadra models are exceptions to this), so their count value is higher. The interval value should be based on the speed of the network and how many devices of this type you expect there to be on the network. On a network with very slow connections (for example, one using a modem bridge), or in cases where there are so many devices of a particular type that lots of collisions occur during lookups, the interval value should be increased. Apple puts these values in a resource because not all networks and devices are alike. You should do the same (put your interval and count in a resource so that it can be configured). Don't access the MPW NBP EntityName field directlyDate Written: 1/1/91 Last reviewed: 6/14/93
When I fill in the fields of MPW's Name Binding Protocol (NBP)
The real definition of
The point is that you should never try to access the fields of the Downloadables
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