A legal (user"defined) DSAP address takes the following form (note the •0" in the second bit):
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Last Bit | First Bit | ||||||||||
Transmitted | Transmitted | ||||||||||
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| D | D | D | D | D | D | 0 | I/G |
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Legal DSAP Address
Certain DSAPs are defined by the IEEE 802.2 Standard for reserved use, that is, they are administered by the IEEE. They are of the following form (note the •1" in the second bit):
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Last Bit | First Bit | ||||||||||
Transmitted | Transmitted | ||||||||||
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| D | D | D | D | D | D | 1 | I/G |
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Reserved DSAP Address for IEEE 802 Definition
For example, the IEEE administers the following DSAP values as follows:
DSAP Value |
| Description |
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FF (hex) |
| Global DSAP, consisting of the I/G bit set to •1", and the seven DSAP | |
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| address bits set to •1". The Global DSAP designates the group of all active | |
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| DSAPs to receive the packet data. | |
02 (hex) |
| DSAP for individual Logical Link Control management functions (as | |
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| defined by the IEEE), consisting of the I/G bit set to •0", and the seven | |
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| DSAP address bits set to •0000001". (Do not associate this DSAP with the | |
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| Hewlett"Packard Node Manager software.) | |
03 (hex) |
| DSAP for group Logical Link Control management functions, consisting of | |
| the I/G bit set to •1", and the seven DSAP address bits set to •0000001". | ||
06 (hex) | DSAP for Internet Protocol (IP), based upon a Defense Advanced | ||
| Research Projects Agency (DARPA) standard for an internetwork protocol. | ||
| The I/G bit is set to •0", and the seven DSAP address bits are set to | ||
| •0000011". (Note: HP networking software uses IP and therefore requires | ||
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| the use of this DSAP. This is in addition to HP reserved SAPs described | |
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| below.) | |
A special predefined value is the •Null" DSAP. The Null address neither identifies a Network Layer process nor management function. Instead, it addresses the Medium Access Control sublayer, which in this case is the LANIC card and firmware.
00 (hex) | Null DSAP, consisting of the I/G bit set to •0" and the seven DSAP address |
| bits set to •0". With the HP 12076A implementation, the card firmware |
| detects a Null DSAP in incoming XID or TEST packets (defined later) and |
| responds appropriately. The driver and upper level software are not |
| accessed. |
General Information 2%9