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2.12 Architecture

From the perspective of clients a network can have two logical structures: client/server or peer-to-peer (p2p).

A client/server architecture (e.g. HTTP) consists of a computer (server) that implements one or more services and another computer (client) that consumes a service.

The client sends a request and the server answers with a response if it likes the format of the request and thinks the client is authorized to ask.

In a Peer-to-Peer-Architecture (e.g. file sharing) all computers are equal.

Everyone can admit and consume a service at the same time.

Most network connections rely on the client/server architecture.

2.13 Gateway

A gateway connects a network with one or more other networks. The most common task of a gateway is to be the so called “default gateway”, the router to whom all packets are sent, which don't match any other local routes of a computers routing table.

Nowadays a gateway manages the connection of a local area network (LAN) with the internet and is therefore equal to a router. Some decades ago a gateway was responsible to translate between different kind of networks like Ethernet and Token-Ring.

2.14 Router

Looking at router you can differ at least two kinds: internet routers administered by your internet service provider (ISP) and home router to connect your LAN to the internet and hopefully protect you from most attacks.

Home-Router are also often called gateways, because they manage the interaction of a network with another. They receive all packets from internal hosts that should be send to some computer on the internet, write their own public IP address received from the ISP as source address into it and forwards them to the next router of the ISP.

Internet routers also forward packets, but they do so by depending on a more or less huge routing table. They don't have a static routing table but use different protocols like RIP, OSPF and BGP to share routing information between each other and find the shortest or otherwise quickest way to the desired destination.

With the help of the command traceroute one can determine all internet routers a packet passes between the own computer and the destination host at least if the router replies on certain packets.


traceroute to ( 1 ( 1.167 ms

2 ( 3 * * *

4 (

5 (

6 (

7 (

8 (

9 (

10 (

11 (

12 (

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