the reason for discard parameter field.
7.9.1.5 Error Report Data Field
This field contains the entire header of the discarded Data PDU, and
may contain some or all of the data field of the discarded PDU.
8 Conformance
For conformance to this International Standard, the ability to ori-
ginate, manipulate, and receive PDUs in accordance with the full pro-
tocol (as opposed to the non-segmenting or Inactive Network Layer
Protocol subsets) is required.
Additionally, conformance to the Standard requires provision of the
protocol functions described in Clause 6. Provision of the optional
functions described in Clause 6.18 and enumerated in Table 9-1 must
meet the requirements described therein. Exceptions to this require-
ment are described in Clause 8.1 below.
Additionally, conformance to the Standard requires adherence to the
structure and encoding of PDUs of Clause 7.
If and only if the above requirements are met is there conformance to
this International Standard.
8.1 Provision of Functions for Conformance
The following table categorizes the functions in Clause 6 with
respect to the type of system providing the function:
Note:
1. The support of the PDU Composition and Forward PDU functions
is necessary for the generation of Error Report PDUs.
2. The Segment PDU function is in general mandatory for an
intermediate system. However, a system which is to be
connected only to subnetworks all offering the same maximum
SDU size (such as identical Local Area Networks) will not
need to perform this function and therefore does not need to
implement it.
If this function is not implemented, this shall be stated
as part of the specification of the implementation.
3. The correct treatment of the padding function requires no
processing. A conforming implementation shall support the
function, to the extent of ignoring this parameter wherever
it may appear.
4. This function may or may not be supported. If an
implementation does not support this function, and the
function is selected in a PDU, then the PDU shall be discarded,
and an ER PDU shall be generated and forwarded to the
originating network-entity if the Error Report flag is set
and the conditions of Clause 6.10.4 are satisfied.
5. This function may or may not be supported. If an implementation
does not support this function, and the function is selected
in a PDU, then the function is not performed and the PDU is
processed exactly as though the function had not been
selected. The PDU shall not be discarded for this reason.
___________________________________________________________________
| Function | Send | Forward | Receive |
|____________________________|____________|___________|___________|
| PDU Composition | M | (Note 1) | (Note 1) |
| PDU Decomposition | M | - | M |
| Header Format Analysis | - | M | M |
| PDU Lifetime Control | | M | I |
| Route PDU | - | M | - |
| Forward PDU | M | M | (Note 1) |
| Segment PDU | M | (Note 2) | - |
| Reassemble PDU | - | I | M |
| Discard PDU | - | M | M |
| Error Reporting | M | M | M |
| Header Error Detection | (Note 3) | M | M |
| | | | |
| Security | - | (Note 3) | (Note 4) |
| Complete Source Routing | - | (Note 4) | - |
| Complete Route Recording | - | (Note 4) | - |
| Partial Source Routing | - | (Note 5) | - |
| Partial Route Recording | - | (Note 5) | - |
| Priority | - | (Note 5) | - |
| QoS Maintenance | - | (Note 5) | - |
| Congestion Notification | - | (Note 5) | - |
| Padding | - | (Note 5) | (Note 3) |
|____________________________|____________|___________|___________|
Table 8: Categorization of Functions
Key:
M: Mandatory Function; this function must be implemented.
-: Not applicable.
I: Implementation option, as described in the text.
NOTE: See notes above