It needs to be reiterated that most of these solutions were conceived for delivering
commercial services other than Ethernet and, in fact, primarily continue to serve that
purpose. Thus, while assessing any of these ???Ethernet??? solutions, one must consider its
primary functionality and its relevance in this broader context.
Different (OSI Layer) Functions The Carrier Ethernet solutions discussed provide functionality
that can be categorized across Layer 1, 2, and/or 3 of the OSI model (the
physical, link, and/or network layer, respectively). As such, they either merely serve
as a transport mechanism for delivering Carrier Ethernet services (basically enabling
point-to-point E-Line services) or also, provide switching and routing functionality that
will allow them to provide multipoint E-LAN services. Figure 16.2 illustrates the OSI
defined functionality that is provided by the different solutions.
Carrier Ethernet attributes may inherently be present in the ???base??? solutions, either
partially or fully; for example, reliability is an attribute that is inevitably present in
all SONET/MSPP solutions (even pre-Carrier Ethernet).
Pages:
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126