Question Description

An office has 5 floors and will support 125 officers. There are 15 support staff and a senior management team of 5. There are 25 networked printers that are used. The bank houses 5 servers of different kinds (for email, web, file storage, database and domain server). The office and support services operate during core hours of 9 am to 6 pm physically and also support online access and services for 24 hours, except for maintenance periods.
KEY REQUIREMENTS
Performance
All banking floor transactions must complete in less than 1ms
All supporting transactions must complete in less than 5ms
Availability (on a monthly basis)
Banking availability must be 99.999%
Support services availability must be 99%
Security
Secure external link to the Internet
Secure connection for remote workers
Internal security mechanisms, including access controls

Cost effective
Overall TCO lower than current TCO (assumptions can be made)
Manageable services that will reduce power usage and maintenance requirements
5 FUNCTIONAL REQUIREMENTS
We require a new network that will meet the key requirements outlined in Section 4. The network will handle all of the data traffic from banking officers themselves and it must be handled with high performance and availability requirements. The requirements for all other traffic are less rigorous. 
The new networks must continue to provide this level of service for a minimum of 5 years, and so must be designed with this in mind. 
The network must provide a cost effective solution showing a simple costing table. 
6 TECHNICAL REQUIREMENTS
Technical requirements are as follows:
IPv4 Protocol and subnetting can be used. You can choose your own Class C IPv4 address. VLSM (Variable Length Subnet Mask) subnetting should be done showing optimal IP address allocation. A subnetting table should be shown. 

Ethernet (IEEE 802.3) is required. VLAN designs on switches can be implemented. STP (Spanning Tree Protocol) with switches can be implemented

Backup and restore functionalities and options for disaster recovery. Optional: Off-site (single or multiple) network option for backup can be shown on another site or multiple sites. Routing protocols like OSPF, RIPv2, EIGRP or alternative internal routing protocol can be used to connect the multiples sites or you can use static routes.

Security - Internal security measures must be explained and a Firewall/IDS/IPS is required

A good internet connection (possibly with fibre optic technology or ADSL)

Detailed network design diagram must be provided.