Foremost, the unrivalled bandwidth capacity of DWDM transmission/switching
systems makes EoWDM by far the most scalable approach for high-density/high-speed
data port aggregation, for example, n ?— 10 Gigabit Ethernet. By contrast, SONET/SDH
or MPLS switching platforms are simply not cost-competitive at multiterabit switching
rates. Moreover, EoWDM can enforce hard-QoS guarantees at all network loadings,
and this capability is only matched by EoS??”also a circuit-switching technology??”
albeit at much lower absolute loadings. Conversely, packet-switching solutions (such
as EoMPLS, EoRPR, Ethernet switching) use more complex scheduler and priority
mechanisms to enforce ???relative??? separation between coarse classes of service (CoS). At
the carrier level, this requires a level of over-engineering as latency performance is very
load-dependent [12], further increasing CAPEX and lowering amortization/payback
periods. Also note that next-generation SONET (NGS)/multiservice provisioning
platform (MSPP) technologies have become very popular with incumbents and can
deliver very high efficiency and carrier-class OAM (see Chapter 11). Nevertheless,
Feature
Ethernet
Switching
Ethernet-
SONET
Ethernet
MPLS
Ethernet
RPR
Ethernet-
Fiber
Ethernet
WDM
Topologies Mesh Linear, ring,
mesh
Mesh Dual ring Point-topoint
Linear,
ring, mesh
Service types EPL/EVPL,
ELAN/EVPLAN
EPL/EVPL EPL/EVPL,
ELAN/
EVPLAN
EPL/EVPL,
ELAN/
EVPLAN
EPL EPL
Scalability Medium (Gbps) Medium (Gbps) Medium(Gbps) Medium
(Gbps)
Medium
(Gbps)
High
(Tbps)
Granularity Very fine
(kbps-Mbps)
Fine (VT1.
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