Network Fundamentals for Doctors

The small office network

The typical medical office will have a network. Usually this will be a Windows Active Directory network with a domain controller. It is useful to consider networks at various layers: Layer 1 – the physical network – cat6 cabling and/or wireless (bits)Layer 2 – the data-link layer – ethernet or 802.1 wireless (frames)Layer 3 – …

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Switches, Routers and Firewalls

These devices are the hardware that connects the endpoints on the network A switch is essentially a layer 2 Ethernet device A router is a path between two subnets A firewall is a device that controls the traffic between two network segments

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Network Switches

The network switch is like a powerboard for the network.  Each device is plugged in and it facilitates communication.  Devices might be workstations printers network attached storage OCT machine and so on They are essentially layer 2 devices – they work on Ethernet frames and MAC addresses.  The physical interface (the part where the network …

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The IP network

Recall that the MAC address was (usually) set by the manufacturer and should be globally unique for a device. But where does the IP address of a device come from? The IP address of a device is set by the user or network administrator.  There are a number of key elements IP address : 4 …

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Routers

A router connects subnets. To do this it takes an ethernet frame, unpacks the IP (layer 3) packet within it, works out what to do with it, repackages it up into a new ethernet frame and sends it out another interface to the “next hop”. This consumes a fair amount of computing resources – routing …

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Network Address Translation (NAT)

In thIe previous example, we had a router connecting our two private networks – the office network 192.168.0.0/24 (the /24 means a subnet mask of 255.255.255.0) and 192.168.10.0/24 So C1 sends the data to an interface on R1, R1 determines the destination is via its other interface and send the data on to O1. O1 …

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Firewalls

A firewall is a device that separates two network segments and filters the flow of packets between them. In general, firewalls are routers (routed firewall) but they can be between separate physical parts of the same subnet. This is known as a transparent firewall. In this scenario, you would have two switches, each connected to …

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The way back – Static routes

Our recommendation is to segment part of the network behind a routed firewall to protect backups and virtual hosts. The problem is that computers on our general network cannot find the secure network segment. Our general network, including our virtual servers (not hosts) are on the network 192.168.0.0/24 with a gateway of 192.168.0.1 Consider a …

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Remote File Systems

One feature of computer networks we use at the office is access to files that are on a remote server. This might be a shared drive, a networked attached storage or similar. The capability is also used by much medical and imaging software. Software on the client computer accesses files on a remote computer via …

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Virtual Private Networks (VPN) part 1 site to site

We use VPNs to enhance network security in two ways : site to site VPN and remote access vpn A site to site VPN creates a connection between two private networks via the internet. The simplest example is a business with two sites. Each has its own internet connection site 1 : 192.168.0.0/24 router R1 …

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