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EXP-INTF (Expansion Interface Circuit Pack)
Issue 1 June 2005 1177
In a CSS configuration with duplicated Port Network Connectivity (PNC), EI circuit packs reside
in the Switch Node Carrier (see Figure 64: Center Stage Switch Configuration with Duplicated
PNC on page 1180). In this case, the EI and SNI circuit packs may be connected via a metallic
cable instead of an optical fiber link. Metallic cable should be tested and replaced in the same
manner as optical fiber.
A PN-to-PN connection can be extended through a DS1 converter complex. (See
Figure 65: Fiber Link with DS1 Converter Complex
on page 1181). When discussing problems
that may be related to fiber links, the DS1 converter is considered part of the fiber link. If
diagnosis of the problem points to fiber connectivity and a DS1 converter circuit pack is part of
the connectivity, problems with the DS1 converter circuit pack should be investigated (see
DS1C-BD
on page 1077). The DS1 converter circuit pack enters into diagnostics for the EI
circuit pack via such tests as the Neighbor Query test (#237), the Fiber Out-of-Frame test
(#238), the Two-Way Transmission test (#241), and the Packet Transmission test (#589).
In a critical-reliability system, the fiber link’s are duplicated as part of PNC duplication. In a
high-reliability system with a CSS (Center Stage Switch) and unduplicated PNC, a single point
of failure between the media server and the CSS is eliminated by duplicating each link,
consisting of:
● SNI in the CSS to which the PN’s EI connects
● Physical fiber paths between them
These dual connections normally share the call-processing load. Should one of these links fail,
the entire load can be shifted to the operational link.
Figure 61
shows the location of the EI circuit packs in a typical unduplicated PNC, direct
connect configuration.
Figure 61: Direct Connect Configuration with Unduplicated PNC
Slot #
Slot #
Slot # Slot #
2
2
2 1 2 1
CABINET 2 CABINET 3
CARRIER A CARRIER A
CABINET 1
CABINET 1
EPN
EPN
E
E
E E E E
I
FIBER LINKS
I
I I I I
PORT CARRIER
PORT CARRIER
PPN
PPN