Installation guide

22 DC 900-1564A
Synchronous Link Control (SLC) Programmer’s Guide
2.2.1 Network-level Support
When the application configures an ICP link for SLC protocol service, it specifies
whether high-level network service or low-level network service is required. The appli-
cation formats each outgoing message and interprets each incoming message, in con-
formance with the message format for the specified network-level service.
2.2.2 Message Blocking Support
Message blocking support allows the application to send and receive each message in its
entirety. The application specifies the attributes of each message sent, and the SLC pro-
tocol reports the attributes of each message received.
The ICP handles the message blocking and block handling procedures of the SLC pro-
tocol. The ICP provides generation and checking of the transmission sequence identi-
fier and the message block identifier within information blocks, as well as automatic
link control block generation and checking for block acknowledgment.
2.2.3 Multi-channel Support
Multi-channel support allows the application to assign up to seven ICP links to support
an SLC network connection. Use of multi-channel support increases the traffic
throughput capacity of an SLC network connection by distributing message traffic over
multiple physical communications channels.
2.2.4 Retransmission Support
Retransmission support allows the application to send a message once, relying upon the
ICP to handle both block-level and message-level retransmission requirements of the
SLC protocol. After a configurable number of successive message retransmissions with-
out receipt of the corresponding acknowledgment, the ICP reports the failure to the
application.