Lucent Technologies DEFINITY Enterprise Communications Server Release 5, CallVisor, ASAI Protocol Reference Instructions Manual

							Management Information Message (MIM)
Issue 6 June 1997
3-3
Management Information Message 
(MIM)
This message is currently used in ASAI only to enable and disable the ECS 
alarming of an ASAI link. This document contains only the necessary subset of 
the MIM and its related procedures. See the 
ISDN Basic Rate Interface (BRI) 
Specification
 for a complete discussion. The MIM carries only the global CRV on 
an ASAI link.
Message type: Management Information Message (MIM)
Direction: both
REGister Message
The REGister message carries the initial capability invocation that initiates an 
ASAI association and assigns a call reference value that the endpoint uses for the 
duration of that ASAI association.
Message type: REGister
Direction: both
Table 3-3. Management Information Message (MIM) Content
Information Element Direction Type Length
Protocol discriminator both M 1
Call reference both M 2-3
Message type both M 2 
Locking Shift to Code Set 6 both M 1
Management Information Element both M 6-?
Table 3-4. REGister Message Content
Information Element Direction Type Length
Protocol discriminator both M 1
Call reference both M 2-3
Message type both M 1
Locking Shift to Code Set 6 both M 1
Facility both M 8-? 
						

							Message Descriptions
3-4Issue 6 June 1997 
RELease COMplete Message
The RELease COMplete message ends an ASAI association.   The sending and 
receiving endpoints release the CRV.
Message type: RELease COMplete
Direction: both
RESTart Message
The RESTart message may be sent from either side of the ASAI interface to 
request the recipient to restart the ASAI interface. The sending endpoint clears all 
ASAI associations in progress on the interface and expects the receiving endpoint 
to do the same and then acknowledge the request.
NOTE:
Clearing a Call Control association does not affect the call.
Although in the 
ISDN Basic Rate Interface (BRI) Specification RESTart is an 
optional message in the terminal-to-ECS direction, adjunct support of this 
message is mandatory in that direction on an ASAI.
NOTE:
The Call Reference Value is encoded as the Global CRV, and the Restart 
indicator is coded to “all interfaces.”
Table 3-5. RELease COMplete Message Content
Information Element Direction Type Length
Protocol discriminator both M 1
Call reference both M 2-3
Message type both M 1
Cause both O 4-22
Locking Shift to Code Set 6 both O 1
Facility both O 8-? 
						

							RESTart Message
Issue 6 June 1997
3-5
Message type: RESTart
Direction: both
Table 3-6. RESTart Message Content
Information Element Direction Type Length
Protocol discriminator both M 1
Call reference both M 2-3
Message type both M 1
Restart Indicator both M 3
Locking Shift to Code Set 6 both 0 1
Version IE both O 3-7
(multiple IEs allowed) 
						

							Message Descriptions
3-6Issue 6 June 1997 
RESTart ACKnowledge Message
The RESTart ACKnowledge message acknowledges the receipt of the RESTart 
message and signifies that the requested restart of the ASAI interface is 
complete.
Although in the 
ISDN Basic Rate Interface (BRI) Specification this is an optional 
message in the terminal-to-ECS direction, adjunct support of this message is 
mandatory in that direction on an ASAI.
NOTE:
The Call Reference Value is encoded as the Global CRV, and the Restart 
indicator is coded to “all interfaces.”
Message type: RESTart ACKnowledge
Direction: both
Table 3-7. RESTart ACKnowledge Message Content
Information Element Direction Type Length
Protocol discriminator both M 1
Call reference both M 2-3
Message type both M 1
Restart Indicator both M 3
Locking Shift to Code Set 6 both 0 1
Version IE both O 3-7 
						

							Status Message
Issue 6 June 1997
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Status Message
The STATUS message is included here for completeness. Certain BRI (hence 
ASAI) implementations may send STATUS in response to protocol errors. 
Although the ECS does not transmit STATUS messages, the ECS recognizes 
incoming STATUS messages as valid messages and does not treat them as ASAI 
protocol errors. The ECS ignores incoming STATUS messages; there is no 
response.
Message type: STATUS
Direction: both
Table 3-8. STATUS Message Content
Information Element Reference Direction Type
Protocol discriminator both M 1
Call reference both M 2-3
Message type both M 1
Call State both M 3 
						

							Message Descriptions
3-8Issue 6 June 1997  
						

							Issue 6  June 19974-1
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Information Elements
This chapter describes the element structure (information element) of the layer 3 
protocol messages.
Every message contains a grouping of the following information elements (IEs):
nThe BRI protocol discriminator
nCall Reference Value (CRV)
nMessage type
nMandatory information elements, as required
nAdditional information elements, when required
The first three elements are common to all the messages and must always be 
present, while the last two elements are specific to each message type.
Figure 4-1 illustrates this message structure. 
						

							Information Elements
4-2Issue 6  June 1997 
Figure 4-1. General Message Organization Example
Unless specified otherwise, a particular information element may be present only 
once in a given message.
The term default means the default value defined is used in the absence of any 
assignment or negotiation of alternate values.
Because an information element may occur several times in a message, the 
ordering of the instances of the information element is important. Chapter 5, ‘‘Byte 
Level Messages’’ explicitly notes where a particular ordering of a repeated 
information element is required. In all other cases, when an information element 
occurs more than once in a message, the receiving endpoint must be able to 
accept those instances in any order.
Every message carries the information elements in a byte structure. Within each 
byte, the bit appointed as bit 1 is transmitted first, followed by bits 2, 3, 4, and so 
on. These bits are assigned the information element values. Their order of 
appearance varies with each message group. Byte 1 is transmitted first also. 
When a field such as the call reference value extends over more than one byte, 
the order of the bit values decreases as the byte number increases. The least 
significant bit of the field is represented by the lowest-numbered bit of the 
highest-numbered byte of that field.
The ISDN Basic Rate Interface (BRI) Specification limits the maximum length of a 
BRI message, hence an ASAI message, to 260 bytes. In all information elements, 
including the Facility IE, the “length of IE contents” (which follows the IE identifier) 
is a single byte. Thus, the maximum binary value that the “length of IE contents” 
field may hold is 255. However, to limit the message to 260 bytes, the maximum 
value that the “length of IE contents” field can take on is less than the maximum 
binary value of 255. Consider a typical ASAI message containing a Facility IE. The 8 7 6 5 4 3 2 1
00001000
BRI Protocol discriminator Byte 1
0000Length of
call reference
value (in bytes)2
Call reference value 3
0 Message type 4
Mandatory and additional information
elements as required        etc. 
						

							Protocol Discriminator
Issue 6  June 1997
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value of the “length of IE contents” for the Facility IE that gives a 260-byte 
message is shown in the following table:
Protocol Discriminator
 The BRI protocol discriminator is 0x08, “0 0 0 0 1 0 0 0.”
Call Reference Value (CRV)
ISDN CRVs are unique at an ASAI interface and are present in every ASAI 
message that passes across the interface. ASAI endpoints use the CRV to 
associate a sequence of messages that comprise an ASAI association.
The originating ASAI endpoint assigns a CRV for the ASAI association. These 
values are unique to the origination side within a specific D-channel layer 2 logical 
link connection. The CRV is fixed for the duration of the ASAI association. Once 
the association ends, the originating endpoint may assign the CRV to a later 
association.
Figure 4-2 shows the structure and encoding of the ISDN CRV.Message Component 1-byte CRV 2-byte CRV
BRI Protocol Discriminator 1 byte 1 byte
length of CRV 1 byte 1byte
CRV 1 byte 2 bytes
message type 1 byte 1 byte
locking shift to code set 6 1 byte 1 byte
facility IE identifier 1 byte 1 byte
length of Facility IE 1 byte 1 byte
remaining bytes 253 bytes 252 bytes
Total 260 bytes 260 bytes 
						

							Information Elements
4-4Issue 6  June 1997 
Figure 4-2. ISDN Call Reference Value
The CRV has three fields:
nThe length of the CRV
nThe call reference value
nThe call reference flag
The CRV length is the number of bytes that follow the byte containing the length, 
so the length may take on the values “0 0 0 1” (one byte follows), or “0 0 1 0” (two 
bytes follow). Each ASAI interface is administered individually for one- or two-byte 
CRV lengths.
The Global Call Reference value is a CRV with length 1 or 2 (however 
administered for the ASAI link) and value zero.
If the ECS receives a CRV on an ASAI interface where the CRV is not the global 
CRV and has a length different from that permitted on the ASAI interface, the CRV 
is considered invalid and the ECS ignores the message. When the CRV length is 
administered as two bytes for an ASAI interface:
nAn adjunct is permitted to send messages containing a CRV with length 1 
or 2 on that interface.
nThe ECS always sends two-byte CRVs (even though the CRV value may 
possibly fit into a single byte).
Certain ASAI messages (RESTart, RESTart Acknowledge, and MIM) always 
contain the Global Call Reference value.
The call reference flag accepts the values “0” or “1.” An originating ASAI endpoint 
always sets the flag to “0;” the destination ASAI endpoint always sets the flag to 
“1.” Furthermore, the interface receiving a CRV first complements the flag before 
using the CRV internally. For example:
If the adjunct originates an ASAI association with a CRV of 64, the adjunct 
would code byte 2 of the CRV as “0 1 0 0 0 0 0 0.” Messages from the ECS for 
this ASAI association would have a CRV with byte 2 coded as “1 1 0 0 0 0 0 0.”8 7654321
 
0  
0 
00 Length of 
call reference 
value (in bytes)Byte 1
Flag Call Reference Value 2
 Call Reference Value — 2nd byte           2a