Nortel INM 4.1, Planning Manual

Page: 49 / 202

INM 4.1 New Feature Description 49 of 202
INM Release 4.1 Planning Guide PG OC 98-13 Issue 1.2
Drop and Continue on Protection (DCP)
1
INM Broadband Release 4.1 introduces a new Drop and Continue on
Protection (DCP) protection scheme for provisioning bidirectional matched
node connections on OC-12 Bidirectional Line Switched Rings (BLSRs), and
provisioning unidirectional and bidirectional matched node connections on
OC-48 BLSRs. Until now, the only protection scheme supported was the Drop
and Continue on Working (DCW).
The DCW protection scheme was first introduced in OC-12 Release 10 and
OC-48 Release 9. This scheme applies only to matched node connections. In
a matched node connection, primary and secondary gateway nodes are
selected to provide survivability for interconnected rings. When such gateways
are established, a survivable path is set up between the primary gateway node
and the secondary gateway node providing protection against single failure
scenarios. The primary and secondary gateway nodes also identify a primary
path and a secondary path as shown in Figure 10 on page 49.
Figure 10. Matched node connection
Prior to the DCP protection scheme, the only protection scheme used for
provisioning the secondary path was the DCW (Drop and Continue on
Working) protection scheme. In this scheme, the working bandwidth is used
for carrying the traffic between the primary and the secondary gateway nodes.
The DCW scheme uses the same working channel used for carrying the traffic
over the primary path. Figure 11 on page 50 shows an example of a matched
node connection using the DCW protection scheme.
1
DCP is being introduced in OC-48 Release 14.1 and OC-12 Release 13.
Primary
A
Secondary P
ath
E
Ring 1 Ring 2
Secondary P
ath
Ring 3
H
F
I
G C
D
Gateway
Secondary
Gateway
Primary Path
B
Drop and
Continue