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Description:
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atmfAtmServiceLayer3ProtocolId OBJECT-TYPE
SYNTAX OCTET STRING
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"This object shall be used to select a user plane layer 3 protocol
(or user plane layer 2 bridging). The first octet of this object
shall be encoded as follows. Bits 5-7 (i.e., the three most
significant bits) shall be set to 0; any other values shall be
ignored. Bits 0-4 (i.e., the five least significant bits) shall be
encoded as shown in the entry for 'User information layer 3
protocol (octet 7)' in Table 4-10/Q.2931. However, if no user plane
layer 3 protocol is specified, then the first (and only) octet
shall be encoded as '0b00000000'.
a) If ISO TR9577 network layer protocol identification is to be
used, then the first octet shall be encoded to indicate 'ISO/IEC
TR9577'. In this case, either:
i) the user plane layer 3 protocol is to be selected in the
management plane. The second octet of this object shall
contain the ISO/IEC TR9577 Initial Protocol Identifier (IPI).
- For layer 3 protocols for which ISO/IEC has assigned a
Network Layer Protocol Identifier (NLPID), then this NLPID
shall be used as the IPI, and the length of the octet
string shall be 2.
- For layer 3 protocols for which ISO/IEC has not assigned
an NLPID, the IPI shall be encoded to indicate 'IEEE
802.1a SNAP identifier' (see Annex D of ISO/IEC 9577). The
following five octets (octets 3 through 7) of this object
shall then contain a SNAP identifier, which consists of a
3-octet organization unique identifier (OUI) and a 2-octet
protocol identifier (PID). This SNAP coding shall be used
only if ISO/IEC has not assigned a Network Layer Protocol
Identifier for the layer 3 or layer 2 protocol. The octet
string shall thus be 7 octets long.
- If an IME wishes to indicate that bridged LAN frames are
to be carried in the user plane then the IPI shall be
encoded to indicate 'IEEE 802.1a SNAP identifier'. The
following five octets of this object shall contain a SNAP
identifier, which indicates the bridged protocol.
For consistency with SIG 4.0, use of the ISO/IEC subsequent
protocol identifier (SPI) is not recommended but not explicitly
prohibited as one can envision scenarios where it has utility.
or
ii) the user plane layer 3 protocol is to be selected using
network layer protocol identification in the user plane. The
octet-string shall be one octet long. The first octet(s) of
each layer 3 protocol data unit shall contain layer 3
protocol identification according to ISO/IEC TR9577.
b)If bits 0-4 of the first octet of the octet string are set to any
value other than 'ISO/IEC TR9577', then any subsequent octets shall
be encoded as follows. Bit 7 (i.e., the most significant bit) of
each of these octets shall be set to 0; however, if it is set to 1,
it shall be ignored. Bits 0-6 shall be encoded according to the
codings for octet 7a, octet 7b and octet 7c specified in table 4-
10/Q.2931. If more than one subsequent octet is needed, then octets
shall appear in the order shown in figure 4-16/Q.2931."
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