Chapter 2 Hardware Description
Optimizing Module Placement
2-10
255-700-239
PacketStar
®
PSAX 4500 Multiservice Media Gateway User Guide
, Issue 2
Release 8.0.0
SVC retention preserves active ATM switched virtual connections (SVCs) and
switched permanent virtual connections (SPVCs). However, virtual connec-
tions on calls in a transient state will not be saved. To preserve active virtual
connections, do not remove the active module while it is synchronizing with
the redundant module.
In a redundant configuration, when you upgrade or remove the active mod-
ule, the standby (backup) module now becomes the active module, and the
original active module becomes the standby module. This switchover is
designed to minimize the time the equipment is down.
The standby module supports complete console and SNMP interfaces, in the
same way the active module supports them, except that the standby module
blocks all set operations.
Optimizing Module Placement
The PSAX 4500 system can be used in a variety of configurations. For most
configurations, the location of the I/O modules is not relevant because they
do not consume all of the available bandwidth of the chassis midplane. How-
ever, in high performance systems (using multiple OC-3c or OC-12c mod-
ules) the knowledge of traffic flow can be helpful in achieving maximum
bandwidth efficiency. The speed of the individual segments is highly relevant
when determining maximum bandwidth (refer to the
PacketStar
®
PSAX 4500
Multiservice Media Gateway User Guide
for a description of the midplane seg-
ments). Since the system is scalable, the mix of modules on each segment
determines the exact speed of the segment.
The PSAX I/O and server modules perform at two speeds: low-speed modules
run at 620 Mbps and high-speed modules run at 1.2 Gbps.
Refer to the following considerations when installing PSAX I/O and server
modules in the chassis for optimum traffic flow:
•
The midplane has four segments. Table 2-2 lists how the midplane is struc-
tured and what modules can be installed in each segment.
Refer to Table 26 for a list of I/O and server module chassis speed designa-
tions. When loaded with high-speed modules, Segments 1, 2, and 3 have a
maximum bandwidth of up to 1.2 Gbps each. When loaded with low-speed
modules, the segments have a maximum bandwidth of 620 Mbps.
Table 2-2. PSAX 4500 Midplane Slot Structure
This Segment…
is composed of
these slots…
and can accommodate these
types of modules…
Segment 1
1–4
High- and Low-speed
Segment 2
5–8
High- and Low-speed
Segment 3
9–12
High- and Low-speed
Segment 4
13–17
Low-speed and CPU2 only
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