5Signal lines, access points

In terms of the focus of this chapter, the concept of network infrastructure is a key concept.

Network Infrastructure:

- provides communication and data exchange between two communicating systems
- allows sharing of resources/network devices on a large scale
- provides single service sharing for multiple devices/clients such as file server, database software, client authentication
- connects hardware products and their software to one local area network (LAN)
- allows you to connect multiple local LANs across geographically large WANs, such as the Internet

Signal lines are essential for data exchange / communication:

- optical
  - data is transmitted through optical fibers arranged in optical cables
  - an advantage is the high resistance to electromagnetic interference
  - they are mainly used in backbone networks
  - the individual fibers are terminated by optical connectors - LC (Lucent Connector), SC (Standard/Subscriber Connector), ST (Straight Tip), FC (Fiber-optic/Ferrule Connector) and many others
  - active element ports are mostly often SFP (Small Form-factor Pluggable) or SFP+
- metallic
  - data is transmitted by metallic pairs arranged within a cable - such as UTP (Unshielded Twisted Pair), STP (Shielded Twisted Pair)
  - categories of cables are CAT5e, CAT6/6a (most common), CAT 7/7a, CAT8
  - typically, the RJ-45 (Registered Jack-45) is used as termination, also referred to as 8P8C (8 Position 8 Contact)
  - active element ports differ according to data bandwidth (FastEthernet/Gbit/5Gbit/10Gbit)
- wireless
  - data is transferred in an open space (air)
  - these connections exhibit lower data throughput and are very sensitive to interference
  - they are mainly used in access networks (according to IEEE 802.11)
  - operating bands are in the order of GHz units

The network infrastructure can be further subdivided into individual elements:

1. passive elements - cables, racks, patch panels, optical tubs and other installation material
2. active elements
   1. Switch - allows you to create individual segments of the local area network, optionally also enables PoE / PoE+ (Power over Ethernet) local power management, L2/L3 management, cloud management
   2. Router - connects multiple LANs or interconnects two or more geographically distant networks, provides routing between these networks using a static or dynamic routing table, creating secure communication tunnels (e.g. IPsec VPN (Internet Protocol Security Virtual Private Network)), allows filtering of traffic (antispam, antivirus, firewall)
   3. Access Point - suitable for building access networks or for connecting client devices to the local LAN, it can operate in Access Point/Client/Repeater mode; implementation of MIMO (Multiple Input Multiple Output) and MU-MIMO (Multi User MIMO) versions of 2×2:2, 3×3:3 and 4×4:3, in order to achieve maximum throughput, the same standards must support both the access point and the client

Current forms of solutions for network infrastructure connection:

- On-Premise - all network infrastructure assets are physically managed by the company
- Cloud - all network infrastructure assets are managed by a service provider, the company only uses services from the offer
- Hybrid - some parts of network infrastructure assets are under company management, some parts of network infrastructure resources are under the management of a provider