363-206-295
Applications
Issue 1
December 1997
2-15
Dual Homing
2
End-users are demanding service with higher and higher availability. Service
providers are responding with tariffs that rely on self-healing networks to offer
such high availability service. Some of these tariffs even call for penalties for the
service provider when service is interrupted or has a high error rate. The Lucent
SONET product family offers many options for meeting these service needs.
OC-1 Ring transport on OC-3 Ring and OC-3 Ring transport on OC-12 ring
networks can be implemented in dual homing configurations.
Dual Ring Interworking (DRI)
2
In an interconnected ring or DRI topology, two rings are connected together at two
geographically separate nodes. In addition to the facility and node failure
protection that a single ring provides, the dual node interconnection between the
rings provides an automatic alternate route in the event of a catastrophic failure at
one of the interconnecting nodes. Typically, such a topology is used to
interconnect a loop feeder access ring to a higher bandwidth interoffice ring as
shown in Figure 2-9. This architecture can withstand any single equipment or fiber
failure in each of the rings or a failure (which could range from a CO shutdown in
the case of fire, for example, or equipment failure, or failure of the facility
connecting the two rings) of either of the two interconnecting nodes without losing
service on either the access ring or the interoffice ring. Such a catastrophic failure
would cause a service outage for a simple ring architecture.
