Apple Network Setup User Manual

Page 152

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C H A P T E R 4

Network Setup Protocol Structures and Data Types

152

Protocol Structures

fTSDUSize

The maximum amount of data that packets of this protocol
can carry. Must be 586, which is the basic AppleTalk
datagram size.

fLoadType

Whether AppleTalk is active. See discussion below for
possible values.

fNode

Most recently acquired node number or the fixed node
number to use.

fNetwork

Most recently acquired network number or the fixed
network number.

fRTMPRequestLimit

Must be 3. This field is ignored by current versions of Open
Transport.

fRTMPRequestInterval

The request interval in milliseconds. This field must be 200.
This field is ignored by current versions of Open Transport.

fAddressGenLimit

Address generation limit. The default is 250.

fBRCAgingInterval

The Best Routing Cache (BRC) aging interval in
milliseconds. This field must be 4000. This field is ignored
by current versions of Open Transport.

fRTMPAgingInterval

The Router Table Maintenance Protocol (RTMP) aging
interval in milliseconds. This field must be 5000. This field
is ignored by current versions of Open Transport.

fMaxAddrTries

The maximum number of retries that OT makes when
trying to acquire an address. The default is 4096.

fDefaultChecksum

When set to

TRUE

, a checksum is performed on the DDP

packet. When set to

FALSE

, no checksum is performed. The

default is

FALSE

.

fIsFixedNode

Set to

TRUE

when fixed node and network numbers are

being used. The default value is

FALSE

.

fMyZone

The most recently acquired zone.

For a detailed description of DDP, see Inside Macintosh: Networking with Open
Transport
and Inside AppleTalk, Second edition.

The value of the

fLoadType

field controls whether AppleTalk is active. The

original definition of this field was as an inactivity timeout (in minutes), similar
to the inactivity timeout implemented for TCP/IP in current versions of Open
Transport.

Before Open Transport 1.0 was released, it was realized that loading and
unloading AppleTalk on demand was not possible, so the

fLoadType

field was

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