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

Overview
Issue  6 June 1997
7-7
11
Link Down
ASAI data messages 
cannot be exchanged.1
Octet 5 contains the link 
down reason.
Octet 5 Value and 
Description: 
101 DEFINITY ECS is 
down.
102 Virtual BRI port    
busied-out or not 
administered. 
103 DEFINITY ECS has 
taken layer 2 down.
104 Virtual BRI port       
busied-out on 
DEFINITY LAN 
Gateway system 
assembly.
(Continued on next page)
Table 7-2. TCP Tunnel Protocol Message Header Values  — (Continued)
Octet 1 value
Message Type
Value and...

TCP Tunnel Protocol
7-8Issue  6 June 1997 
6
Heartbeat 
This message can be 
used to determine the 
health of an 
ASAI-Ethernet connection. 
Upon receipt it must 
immediately be 
responded to with a 
‘‘heartbeat reply’’ 
message.0-255Invoke ID 
This value is repeated by 
the 
Heartbeat Reply to 
allow correlating the 
response to the request.0
No additional data.
7
Heartbeat Reply
0-255
Invoke ID 
This value should be set to 
the same value as the 
Heartbeat Invoke ID 
received in the 
Heartbeat...

Tunnel Protocol Procedure
Issue  6 June 1997
7-9
Tunnel Protocol Procedure
The method by which the messages in Table 7-2 are exchanged in order to 
establish an ASAI-Ethernet connection for ASAI messages is as follows:
1. The client opens a TCP connection to port 5678 on host 
definity.
2. The brouter accepts the connection, and either retains it or sends an 
Error 
Notification
 message and closes the connection.   The normal case is to 
retain the connection. The 
Error Notification message may be sent...

TCP Tunnel Protocol
7-10Issue  6 June 1997 
decide whether to wait or to abort the connection. Finally, a Heartbeat 
message may be sent, and should be replied to immediately with a 
Heartbeat Reply message. Additional information about Heartbeat 
messages follows in this chapter.
7. When the client decides to terminate the connection, it should send a 
Disconnect Notification message. The client is free to immediately close its 
TCP connection after sending this message.
8. Upon receipt of the...

Tunnel Protocol Procedure
Issue  6 June 1997
7-11
Table 7-3. Typical Successful Connection Scenario
Client Connects While ASAI Link is Down
A typical scenario of a client connecting while its ASAI link is down follows:
nThe client opens a TCP connection to port 5678 on host definity.
nClient sends server a Connection Request message with octet 5 set to the 
client’s link number (3) and octet 6 set to the client’s TCP Tunnel protocol 
version number (1).
nServer responds with a Connection Accepted message...

TCP Tunnel Protocol
7-12Issue  6 June 1997 
nThe client and server are now connected and bring up ASAI.
nEventually the client decides to terminate the connection and sends a 
Disconnect Notification message.
nBoth client and server close the TCP.
Table 7-4. ASAI-Link Down Scenario
Client
CTI-host, link 3, version 1 DirectionDEFINITY LAN Gateway
definity, version 1
TCP open to definity
Connection Request
1,0,0,2,3,1
Connection Accepted
Link Down
2,11,0,1,101
Link Status, Link Up
5,10,0,0
ASAI Data (Q.931...

Tunnel Protocol Procedure
Issue  6 June 1997
7-13
Invalid TCP Tunnel Protocol Version Scenario
A typical scenario where a client connect request is rejected because of an 
unsupported tunnel protocol version follows:
nThe client opens a TCP connection to port 5678 on host definity.
nClient sends server a Connection Request message with octet 5 set to the 
client’s link number (3) and octet 6 set to the client’s TCP Tunnel protocol 
version number (2).
nServer responds with a Connection Rejected message...

TCP Tunnel Protocol
7-14Issue  6 June 1997 
Error Notification Scenario
The server may send an Error Notification message and then close the 
connection at any time. The client should immediately close its TCP connection 
whenever it receives this message.
Table 7-6. Error Notification Scenario
Client
CTI-host, link 3, version 1 DirectionDEFINITY LAN Gateway
definity, version 1
ASAI Data (Q.931 Msg.)
8,0,X,X,8,2 ...
ASAI Data (Q.931 Msg.)
8,0,X,X,8,2 ...
Error Notification
0,2,0,0
Close (TCP) Close (TCP) 

Tunnel Protocol Procedure
Issue  6 June 1997
7-15
ASAI Link Status Scenario
A typical scenario depicting changes in link status follows. Links may be 
unadministered or busied out at any time on DEFINITY ECS. Layer 2 may also be 
brought down on a hyperactive link by DEFINITY ECS.   To relay this change in 
link status, the server sends 
Link Status messages, which clients may receive at 
any time.
When a message arrives with the cause set to 
Link Down, the client should stop 
sending 
ASAI Data to the...

TCP Tunnel Protocol
7-16Issue  6 June 1997 
Network Outages
It is possible for an established TCP connection to be unable to pass data from 
client to server (or vice versa). A number of problems, including the following, can 
cause this situation:
nA router failure between client and server
nA physical media failure between client an server
nA failure in either the client or server
TCP can detect such conditions and close down the connection; however, this 
may take up to 15 minutes. 
CallVisor ASAI...