In a collapsed core design, which two benefits are provided by a second-generation Cisco MDS director? (Choose two.)
A.
a higher fan-out ratio
B.
fully redundant switches
C.
100 percent port efficiency
D.
all ISLs contained within a single chassis
E.
higher latency and throughput than a core-edge design switch
Explanation:
As per “Designing.Cisco.Network.Service.Architectures.ARCH.Foundation.Learning.Guide.3rd.Edition, Chapter-6 Designing SANs, pg 333 and 334 ”
Correct answers are
1) high fan out ratio
2) 100% port efficiency.
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Single-Switch Collapsed-Core Design
The collapsed-core single-switch design takes a traditional core-edge topology and collapses it into a single chassis. Instead of using many small switches to provide sufficient port density, a single chassis with a high port count replaces the smaller switches. This design reduces the number of ISLs required in the network so that all available ports can be deployed for host or storage connections, leading to 100 percent port design efficiency.
In Figure below, the backplane of the MDS in the collapsed-core design replaces all the ISL links. This design can also provide a lower fan-out ratio than the multiple small switches because the availability of more advanced blades for the MDS. Empty slots on the MDS can support future growth on new line cards.
The collapsed-core design on a first-generation switch has limited capabilities with regard to high availability. With later-generation Cisco MDS series switches, dual redundant crossbar switch fabrics are used on all director switches to provide low-latency, highthroughput, nonblocking, and non-oversubscribed switching capacity between line card modules. In addition, the port bandwidth reservation feature guarantees dedicated performance for those devices that require it.
Note Second-generation MDS 9500 series director switches are fully redundant with no single point of failure with dual supervisors, crossbar switch fabrics, clock modules, or power supplies. Nonetheless, note that this design still has a single point of failure with the one chassis.
Reference: Designing Cisco Network Service Architectures (ARCH) Foundation Learning Guide – 3rd Edition, Pages 333 – 334
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correct answers are:
B. fully redundant switches
C. 100 percent port efficiency
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if it is “low fan-out ratio” then it will be a correct answer.
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