MK50H28N ST Microelectronics, Inc., MK50H28N Datasheet - Page 13

• Manufacturer Part Number: MK50H28N
• Description: Multi Logical Link Frame Relay Controller
• Manufacturer: ST Microelectronics, Inc.

Table 1 - MK50H28 Frame Types
3.2.8 Modes of Protocol Operation
The User mode of operation is entered by issuing
an Auto LMI primitive 7 with UPARM=0. In this
mode, the device transmits STATUS ENQUIRY
messages to the network with an interval deter-
mined by the nT1 timer. After every nN1 transmis-
sions of STATUS ENQUIRY with Report Type of
"Length Integrity Verification (LIV) Only" the
MK50H28 transmits a STATUS ENQUIRY with
Report Type of "Full Status".
When a STATUS frame is received in response to
a STATUS ENQUIRY(LIV only), the receive se-
quence number received from the Network side
is checked against the User send sequence num-
ber. A received Full STATUS frame will be stored
into the LMI/LIV channel buffer, the sequence
number checking will be performed, and its recep-
tion will be indicated to the host via Provider
Primitive 13. An available transmit or receive buff-
er is not required for the MK50H28 automatic
processing of "LIV only" frames.
A received Asynchronous STATUS frame will be
stored into the LMI/LIV channel buffer and its re-
ception will be indicated to the host via Provider
Primitive 14. If a STATUS ENQUIRY frame (Full
or LIV only) is received in this mode of operation,
the MK50H28 will discard the frame and incre-
ment the Discarded Frames Counter in Context
Table enrtry 0. Also see nT1 description in 4.2.2
Timer/Counter section.
The Network mode of operation is entered by is-
suing an Auto LMI primitive 7 with UPARM=1. In
this mode, the device automatically responds to
STATUS ENQUIRY with Report Type of "Length
Integrity Verification (LIV) Only" by transmitting a
STATUS frame with Report Type of "LIV Only"
along with restarting the nT2 timer. An available
transmit or receive buffer is not required for the
MK50H28 automatic processing of "LIV only"
frames.
NOTES:
1. STATUS_ENQUIRY Frame - This Frame has the format as shown in Figure 4.
2. STATUS Frame - This Frame has the format as shown in Figure 5. If Full STATUS information is to be sent, the
3. Asynchronous STATUS Frame - This Frame has the format as shown in Figure 6. The host must specify the PVC_
4. UPDATE_STATUS Frame - Not used in most current applications, MK50H28 supported for backwards compatibility.
Message Type
INFORMATION ELEMENT
host must specify the PVC_STATUS Information Element(s) in the transmit buffer(s).
STATUS Information Element in the transmit buffer(s).
STATUS_ENQUIRY
STATUS
UPDATE_STATUS
NAME
User -> Network
Network -> User
Network <-> User
When a STATUS ENQUIRY with Report Type of
"Full Status" is received, the device issues the
LMI Received primitive 13 (with PPARM=1) and
expects the host to respond with an LMI Status
Request Primitive 11 with UPARM=0 (when the
host is ready to transmit the Full STATUS frame).
Asynchronous STATUS frames may be transmit-
ted by placing the data to be transmitted into the
appropriate buffer and issueing Primtive 11 with
UPARM=2. If a STATUS frame (Full, LIV Only, or
Asynchronous) is received in this mode of opera-
tion, the MK50H28 will discard the frame and in-
crement the Discarded Frames Counter in Con-
text Table enrtry 0. Also see nT2 description in
4.2.2 Timer/Counter section.
The Bi-directional Network Procedures mode
is entered by issuing an Auto LMI primitive 7 with
UPARM=2. The MK50H28 supports this opera-
tion using separate User and Network sequence
numbers and N392 and N393 counters. In this
mode, the device transmits STATUS ENQUIRY
messages with a User set of sequence numbers
at an interval determined by the nT1/T391 timer.
The expected response is a STATUS frame with
corresponding sequence numbers. After every
nN1/N391 transmissions of STATUS ENQUIRY
with Report Type of "LIV Only", the MK50H28
transmits a STATUS ENQUIRY with Report Type
of "Full Status".
A received Full STATUS frame will be stored into
the LMI/LIV channel buffer, the sequence number
checking will be performed, and its reception will
be indicated to the host via Provider Primitive 13.
A received Asynchronous STATUS frame will be
stored into the LMI/LIV channel buffer and its re-
ception will be indicated to the host via Provider
Primitive 14.
In this mode, the device also automatically re-
sponds to STATUS ENQUIRY ("LIV Only") by
transmitting a STATUS ("LIV Only") frame along
with restarting the nT2 timer. When a "Full Status"
DIRECTION
MSB
0
0
0
Message Type Encoding
1
1
1
1
1
1
1
1
1
0
1
1
MK50H28
1
1
0
0
0
1
LSB
13/64
1
1
1