DEFINITY Enterprise Communication Server Release 9
Installation and Maintenance for Survivable Remote EPN
555-233-121
Issue 2
November 2000
SREPN Maintenance
2-6
SREPN connections
2
Transfer sequence to Survive mode
Transfer from Normal to Survive mode is automatic and is controlled by the
TN775C Maintenance board.
Figure 2-3
shows a schematic of the link switching
within the TN2301 circuit pack.
Figure 2-3.
TN2301 link switching schematic
The transfer sequence to Survive mode is:
1. Links from the Release 9r PPN to one of its configured SREPNs fail.
2. The TN775C Maintenance circuit pack (A-carrier SREPN) detects the link
failure and signals the TN2301 to disconnect its links to the Release 9r and
connect the SREPN Expansion Interface.
3. The TN2404 Survivable Remote processor (SRP) takes over control of the
EPN in Survive mode on Link A. Link B is left open while the SRP is in
control of the SREPN.
NOTE:
In Survive mode, the SRSwitch (TN2301) puts the EI/SNI circuit pack in the
Release 9r into loopback mode.
Figure Notes:
1. Release 9r
2. Survivable Remote EPN (SREPN)
3. SRSwitch (TN2301)
4. Survivable Remote processor (R9si)
cydfsrp2 KLC 022499
A
A
B
B
TN2301
1
3
4
A
B
2