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PKT-INT (Packet Interface)
Issue 1 June 2005 1811
S8700 | 8710
If the circuit pack’s diagnostic tests do not pass in a standard- or duplex-reliability system
(unduplicated IPSIs), the failing Packet Interface is placed in an out-of-service state. Every link
handled by that IPSI goes down, and may be re-established using other Packet Interface
resources. Calls associated with these links may drop.
If the standby IPSI (in a high- or critical-reliability system with duplicated IPSIs) has an
acceptable state of health, maintenance software interchanges the IPSIs, instead of resetting
the active IPSI’s Packet Interface module. This is less disruptive than a reset.
An IPSI’s Packet Interface module goes out-of-service if the IPSI has been reset by background
maintenance 3 times in the last 15 minutes, whether or not reset succeeded. Various errors will
lead to a Packet Interface reset. See the “Error Log Entries and Test to Clear values” section.
An extensive set of diagnostic tests is run when the circuit pack is reset.
S8700 | 8710
Duplication Impact
The Packet Interface module is a single point of failure in a standard- or duplex-reliability
system, with unduplicated IPSIs. If not acceptable, an S8700 customer can upgrade to a high-
or critical-reliability system with duplicated IPSIs. Figure 104: Distributed PKT-INTs
on
page 1801 shows an S8700 Multi-Connect configuration with duplicated IPSIs. The following
concepts apply to duplicated IPSIs:
● Packet-bus connection
In a high- or critical-reliability system (duplicated IPSIs), the standby IPSI’s Packet Interface
module cannot access the packet bus to write data, except during a planned IPSI
interchange or when the Peer Link test (#888) is run. The Maintenance Loop-Around test
(#886), which requires access to the packet bus, is not run on the standby IPSI’s Packet
Interface module.
● IPSI interchange
Severe Packet Interface module faults that cause system and application links to go down
are detected within 1 second. A fatal fault error message is generated, and the Packet
Interface maintenance software attempts to run the Packet Interface Reset test. In a high-
or critical-reliability system, this results in a requested IPSI interchange, instead of a Packet
Interface reset, since stable calls are preserved across the interchange.