WAN Subsystem Configuration and Management Manual

Overview of the WAN Subsystem
WAN Subsystem Configuration and Management Manual—522463-011
2-30
Fault Tolerance and Fault-Containment
Fault Tolerance and Fault-Containment
Host-system connection fault tolerance is provided primarily by having two Ethernet
connections to the host for each WAN port and allowing the SWAN concentrator to use
either connection. Only one connection is needed for full functionality.
Fault-containment is provided by the independence of the six CLIPs, each of which
controls two WAN lines. If one CLIP fails, the other ten WAN lines remain functional.
Additional fault-containment features include parity on the microprocessor DRAM and
the Ethernet anti-babble circuit that silences a babbling CLIP so that it cannot cause
the other five CLIPs to lose their Ethernet connections.
Path Switching
The SWAN and SWAN 2 concentrator use the same path switching algorithm. For
more information, see Path Switching on page 2-14.
Multisystem Configuration
The multisystem configuration considerations are the same for the SWAN and the
SWAN 2 concentrator. For more information, see Multisystem Configuration on
page 2-17.
Difference Between the SWAN and the
SWAN 2 Concentrator
•
The SWAN 2 concentrator has six CLIPs as compared to three CLIPs on a SWAN
concentrator.
•
The SWAN 2 concentrator CLIPs, WAN BIC, LAN BIC, LAN LB, power supply,
battery, and fan are removable and can be replaced while a NonStop system is
powered-on.
•
The SWAN 2 concentrator is based on a faster processor in the CLIP and provides
increased performance over the SWAN concentrator.
•
The SWAN 2 concentrator has improved fault tolerance due because it has dual
power supplies. One power supply can power all the boards in an enclosure.
•
The SWAN 2 concentrator supports 100Base-T Ethernet and the SWAN
concentrator does not.
•
The SWAN 2 concentrator provides a 30-second ride-through (with a battery)
should the AC power fail. The SWAN concentrator does not support this feature.