Similar to DSAPs, certain SSAPs are administered by the IEEE and take the following form (note the second bit is set to •1"):
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| S |
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Reserved SSAP Address for IEEE 802 Definition
For example, the following SSAPs are reserved and defined by the IEEE:
SSAP Value |
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02 (hex) |
| Command from an individual Logical Link Control management function | |
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| SSAP (as defined by the IEEE). (Do not associate this SSAP with HP | |
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| Node Management software.) | |
03 (hex) |
| Response from an individual Logical Link Control management function | |
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| SSAP. | |
06 (hex) |
| Internet Protocol (IP) SAP. IP, which is based on a Defense Advanced | |
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| Research Projects Agency (DARPA) standard for an internetwork protocol, | |
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| is used by HP networking software. | |
Null SSAPs are also predefined.
00 (hex) | Command Null SSAP. This SSAP originates from the Medium Access |
| Control sublayer (that is, the LANIC card and firmware). |
01 (hex) | Response Null SSAP. This SSAP also originates from the Medium Access |
| Control sublayer. |
Control
The Control field specifies the interpretation of the data in the Information field. The Control field can assume an 8"bit or 16"bit format as defined by the IEEE 802.2 Standard. The 16"bit format contains additional information to allow flow control and error recovery. Thus, the 16"bit format applies when Type 2 services are provided.
The Hewlett"Packard implementation provides Type 1 services only, where the 8"bit Control field applies. The 8"bit format is referred to as •Unnumbered", or •U"Format", Protocol Data Units. In this case, the Control field structure is as follows:
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| M |
| M | M | P/F | M | M | 1 |
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Unnumbered Format for Control Field
General Information 2%11