- NVRAM and Clock Daughter card
- Contains system clock
- Contains active system configuration in NVRAM
- Clock and NVRAM data constantly synchronizes with the redundant unit to allow for very fast switchovers.
- Support of CPU redundancy
- Provides a less-than 250 microsecond active to redundant CPU switchover times.
- Must be used with 893x series Interface cards.
IMACS CPU Redundancy
The 880770 CPU is designed to provide faster active to redundant CPU switch over times on the IMACS controller shelf. This capability has been achieved by a major redesign of the existing CPU and Interface (IF) card hardware. The primary design goal is to provide a more stable environment for public safety services and mission-critical networks by significantly reducing or eliminating service interruption during the CPU switch over process. The previous CPU hardware platform (880370) has typical switch over and recovery time of approximately 12 seconds from the time of the switch to when data is recovered. The new 880770 CPU hardware is designed to reduce CPU switch over and recovery time to less than 250 micro seconds; essentially less than two T1 frames.
In order to provide this capability, the IMACS required changes to the Interface (IF) card and CPU card hardware designs, as well as rudimentary software design changes. These changes focused the Interface card’s system clocking and the NVRAM storage of the system configuration database. Change requirements can be abbreviated into three major components:
- Improve IF card robustness by removing all active system controller functions (system clock and system image NVRAM storage) from the IF card and providing a replaceable OAM controller sub-unit half height card to main IF card frame which maintains copper connectivity to the T1/E1 WAN bus.
- Mirror system controller functions (system clock and system image NVRAM storage) on both active/standby CPU cards facilitating hot standby redundancy.
- Provide fully serviceable NVRAM and clock interface by using a sub-unit module on the main CPU board that can be replaced on the inactive CPU card.
To accomplish these goals, the 880770 CPU is compatible with only the following new Interface Cards: • 893270 IMACS, RDNT, I/F, EXT SYNC, 8P, NO MODEM • 893370 IMACS, RDNT, I/F, 8P, MODEM • 893470 IMACS, RDNT, I/F, W/O MODEM
The 880770 CPU is compliant with the European Union’s Reduction of Hazardous Substances (RoHS) directive currently with the lead waiver. The 880770 CPU will support all of the features of the 880370 cards and features in the v6.x.y Host Code versions. Initially, only certain WAN, Server and User cards have been enabled to switch traffic from one CPU to the other in less then 250 micro seconds. These cards are:
- Server: IPR*4, ADPCM, OC3, PWE
- WAN: All versions of WAN cards
- Data: SRU, LD-SRU, HSU, OHSU
- Voice: FXS, FXO, E&M