OSI/TS Configuration and Management Manual

Introduction
OSI/TS Configuration and Management Manual—424831-001
1-2
Implemented Standards
•
ISO 9542 1988(E) end system to intermediate system (ES-IS) routing exchange
protocol
•
ISO 8208 packet-switched network protocol
•
Data Link Layer (Layer 2)
•
IEEE 802.2 Logical Link Control Type 1 (LLC1)
•
CCITT X.25 link access protocol balanced (LAPB)
•
Physical Layer (Layer 1)
•
IEEE 802.3 baseband
Figure 1-1
illustrates the protocols supported by OSI/TS.
Two types of systems make up an OSI network:
•
End systems, which implement at least the lower four layers of OSI services and in
which application processes run
•
Intermediate systems, which implement only the lower three layers of the model and
which function as relay nodes between end systems
The OSI/TS subsystem supports only end systems—not intermediate systems.
A system of intermediate systems is referred to as a subnetwork. OSI/TS regards local
area networks (LANs) and X.25 wide area networks (WANs) as subnetworks. Any
public, X.25 packet-switched network, or any LAN, can serve as a subnetwork for OSI
end systems.
Figure 1-1. OSI/TS Supported Protocol
101CDT .CDD
Layer
Transport
Network
Data Link
Physical
WAN
OSI Transport
Classes 0-4
ISO 8073
Internet Protocol
ISO 8473
SNDCF
X.25 1980
X.25 1984
LAPB
RS-449, RS-232C, X.21, V.35
LAN
OSI Transport
Class 4
ISO 8073
Internet Protocol
ISO 8473
LLC1
ES-IS Routing
Exchange Protocol
ISO 9542
Baseband