400-007 Exam - Question 8

Question

Refer to the table. A customer investigates connectivity options for a DCI between two production data centers. The solution must provide dual 10G connections between locations with no single points of failure for Day 1 operations. It must also include an option to scale for up to 20 resilient connections in the second year to accommodate isolated SAN over IP and isolated dedicated replication IP circuits. All connectivity methods are duplex 10 Gbps. Which transport technology costs the least over two years in this scenario?

Examice · Accepted Answer

To determine which transport technology costs the least over two years while meeting scaling requirements, we need to consider CAPEX, OPEX, installation fees, and scalability to support up to 20 resilient connections. DWDM (Dense Wavelength Division Multiplexing) supports a higher number of wavelength channels compared to CWDM (Coarse Wavelength Division Multiplexing). This makes DWDM more suitable for the requirement to scale up to 20 connections in the second year. Although the CAPEX and installation fees for DWDM are higher, the ability to scale without significant additional costs makes it the most cost-effective solution over two years.

qtg9rMGmj23tFm4n02X4 · Answer

the hint is the requirement 'option to scale for up to 20 resilient connections in the second year'. this effectively multiplies the estimated cost with 20 times.

DWDM will leverage multiple lambdas across 2 x fibres to provide that scale without additional cost for each connection added. effectively scaling out is amortised into the original contract

bdp123 · Answer

CWDM supports up to18 connections whereas DWDM supports 48 without extra cost
https://www.commscope.com/blog/2019/cwdm-vs.-dwdm-decoding-the-differences-between-wave-division-multiplexing-options/

Pal68 · Answer

CWDM supports up to 18 wavelength channels transmitted through a fiber at the same time. To achieve this, the different wavelengths of each channel are 20nm apart. DWDM, supports up to 80 simultaneous wavelength channels, with each of the channels only 0.8nm apart. CWDM technology offers a convenient and cost-efficient solution for shorter distances of up to 70 kilometers. For distances between 40 and 70 kilometers, CWDM tends to be limited to supporting eight channels.

gcpengineer · Answer

D is the cheapest

gcpengineer · Answer

the question is on cost and D is the ans

TonyGuo · Answer

should be DWDM, scale for up to 20 resilient connections

kzqc · Answer

It is CWDM. 
'option to scale for up to 20 resilient connections in the second year' is a 10x increase from the dual 10G connections in the first year. CWDM can scale up to 18x.

XalaGyan · Answer

I also vote for DWDM has no distance information is given. only contract term, cost and amount of expansion. DWDM is the safer choice in all of those compared to CWDM

Answer B

Devsin2000 · Answer

MPLS Is out as it is not suitable for SAN traffic. 
The effective cost for DWDM and CWDM goes too high due to 5 years contract
Metro Ethernet is cheapest because of the lower contract period.

400-007 Exam - Question 8

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