DEFINITY Enterprise Communications Server Release 7
Maintenance for R7r
555-230-126 Issue 4
June 1999
Maintenance Architecture
1-34Protocols
1
Both the physical-layer protoc ol and the Digital Multip lexed Interface (DMI) mode
used in the connection are d ependent upon the typ e of 8-bit code used at laye r 2
between the DTE equipment and DCE equip ment, as listed in Table 1-9 and
Table 1-10.
Connectivity Rules
Figure 1-9 implies the following connectivity rules:
■Only the DS1 port and the analog trunk port are trunking facilities (all other
ports are line ports). For communic ation over these facilities, the
destination DCE equipment can be a hemisphere away from the system,
and the signal can traverse any number of intervening switching systems
before reaching the de stination equipment.
■Data originating at any type of digital device, whether DCP or BRI, can exit
the system at any type of dig ital port — BRI, digital-line, PRI, DS1, and
others; as long as the call d estination is equipped with a data module
using the same DMI mode used at the c all origin. This is because once the
data enters the system through a di gital port, its representation is uniform
(raw bits at layer 1, and DMI at level 2), reg ardless of where it originated.
Table 1-9. Physical-Layer Protocol Versus Character Code
Protocol Code
RS-232 Asynchronous 8-bit ASCII, and sync hronous
RS-449 Asynchronous 8-bit ASCII, and sync hronous
V.35 Synchronous
Table 1-10. Digital Multiplexed Interface (DMI) Mode Versus
Character Code
DMI Mode Code
0 Synchronous (64 kbps)
1 Synchronous (56 kbps)
2 Asynchronous 8-bit ASCII (up to 19.2 kb ps), and synchronous
3 Asynchronous 8-bit ASCII, and private p roprietary