363-206-285
Administration and Provisioning
8-40 Issue 3 June 2001
OC-3/OC-12 Path Protected Ring Drop and
Continue Application 8
This is a path protected ring application with multiple NEs in a two-fiber ring. All
but two nodes are normal ring application nodes (see previous application). Two
nodes are defined to be the drop and continue nodes and are neighbors. They
function to provide two copies of each service on the ring to another ring (dual ring
interworking) or to wire centers (dual wire center service). Special drop and
continue cross-connections are used to support this feature. The STS1E low-
speed circuit pack is used to transport traffic between rings or to the wire centers.
This feature provides node failure survival functionality. These two special nodes
can also provide normal ring functionality at the same time.
OC-3/OC-12 Path Protected Ring Cross-Connect
Restrictions 8
Restrictions on path-protected ring cross-connections include the following:
â– All VT-1.5 cross-connections (ent-crs-vt1) are done via the OLIU circuit
packs in the main slots. The OLIU circuit packs must be 22-type, 24-type,
26G2-U, 27G-U or 29-type.
â– Time slots in function units A and B cannot be cross-connected to each
other.
â– When function units A and B are equipped with OLIUs, they can only carry
two STS-1 or 56 VT1.5 signals. They cannot be cross-connected with main
or function unit C to carry three STS-1, 84 VT1.5 or an STS3C signal.
â– A cross-connection cannot be made to a slot that is in the unequipped
state. Also, a cross-connection may not be made with any signal where a
cross-connection already exists. The existing cross-connection must be
deleted before a new cross-connection can be entered.
â– If the system is equipped with OLIUs in function unit A and/or B, only one
STS-1 signal per function unit is allowed to be connected (added) to
function unit C.
â– For VT1.5 cross-connections, all drop and continue cross-connections on a
shelf must be entered into the same ring.
â– Use the following rules to establish cross-connections in each ring:
a. All drop connections (including DRI, if present) from the same ring
must be provisioned the same, either all VT1.5 or all STS-1.
b. If all 28 VT1.5s (DS1s) in an STS-1 are being passed through at a
node in a VT1.5 path-switched ring, the cross-connection may be
provisioned as either a pass-through STS-1 or VT1.5. However, if
you anticipate dropping VT1.5s from the pass-through node, you
should provision the pass-throughs as VT1.5 cross-connections.
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