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3.9. LAN

47

set the value to one until it succeeds. You then set it to zero when you are done. This locking mechanism leads to problem if the locker dies while it holds the lock, so you probably need some way to override the lock if this happens. The lock does not actually keep anyone from changing the data, it is simply a common mechanism to mutual exclusion. Note also that the lock has a “commit” mechanism, writing two to the lock will commit the contents if the system supports it. If the system supports rollback, setting the value to zero will rollback and not commit the changes you made. So for correctness, you should write a two when you are complete, and if that fails then write a zero.

All network parameters such as IP address, port, and MAC address are in network order, also called big endian or most significant byte first. Unless marked “volatile”, all of these will survive removal of power.

Table 3.16: LAN Configuration Parameters

Parameter

#

Set In

Progress

0

(volatile)

Description Used to indicate that the parameters are being updated. Bits 2-7 are reserved. Bits 0-1 have the following values: 00b - set complete. This is the state the system comes up in. This means that any user is finished updating the parameters. If roll- back is implemented, setting this value will cause any changes made since last setting this value to “set in progress” to be un- done. 01b - set in progress. A user will set this value to inform others that it is updating these parameters. This value can only be set if the current value is “set complete”. 10b - commit write (optional). This will commit any changes that are pending and go to “set complete” state. Some systems may not support this, if setting this returns an error you should set this value to “set complete” by hand.

Authentication Type Support (Read only) Authentication Type Enables

1

2

IP Address

3

A read only field showing which authentication types are supported. The format for this is defined in table 3.31. A 5 byte field that holds the allowed authentication type for each priv- ilege level. The bytes are:

byte 0 - callback byte 1 - user byte 2 - operator byte 3 - admin byte 4 - oem The format for each byte is defined in table 3.31. A 4 byte field holding the IP address, in network order. This is the local IP address used for this particular channel. You only need to set this is parameter 4 is set to “static address”.

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