Chapter 3 Topology
Physical Topologies
Cisco SCE 2000 4/8xFE Installation and Configuration Guide
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OL-7826-05
Physically Connected Links Parameter
If the system consists of more than one device, this parameter defines which link is connected to
this
SCE 2000
. Currently the system supports a maximum of two links, which are designated link
0 and link 1.
Priority
In a cascade topology, the user must define the priority of each
SCE 2000
.
•
Primary
— The Primary
SCE 2000
is active by default
•
Secondary
— The Secondary
SCE 2000
is the default standby.
Note that these defaults apply only when both devices are started together. However, if the
primary
SCE 2000
fails and then recovers, it will not revert to active status, but remains in
standby status, while the secondary device remains active.
On-Failure Mode Parameter
As described in the section The Bypass Mechanism, the bypass card supports four different
modes. The following two modes are possible when the
SCE 2000
is not operational due to
platform failure or boot:
•
Bypass —
The external switch forwards traffic with no intervention of the control application
running in the
SCE 2000
platform, but monitoring functions continue uninterrupted.
•
Cutoff
— There is no forwarding of traffic. The link is forced down, resulting in traffic cutoff
at Layer1.
The
Forwarding
mode enables control of traffic flow and is not compatible with the non-
operational status.
In a single
SCE 2000
topology, the value of this parameter is determined by whether or not the
link can be completely cut when the
SCE 2000
fails, or whether traffic flow should continue
across the link in spite of platform failure.
•
Cutoff
mode is required for the following:
•
Redundant inline topology.
•
Non-redundant inline topology if value-added services are crucial and are more important
than maintaining connectivity.
•
Bypass
mode is required for the following:
•
Non-redundant inline topology if connectivity is crucial.
