A communication service provider can offer one or many of the following services:
Phone network (fixed and/or mobile)
Internet access (TCP/IP network).
Television.
As you already know, the future is all-IP (convergence between all kinds of networks and TCP/IP1 networks). As a consequence, all these services come from an ISP (Internet Services Provider)
ISPs typically own both a fixed and a mobile (4G) network. The other services (voice, TV) tend to become data traffic:
Fixed telephony (voice) → ToIP (Telephony over IP), or VoIP (Voice over IP).
Mobile telephony (voice) → ToIP (Telephony over IP), or VoIP (Voice over IP).
Cable television, conditional access DVB-T or DVB-S → IPTV.
So ISPs concentrate all these services in what is referred as “Triple play”: voice, data, TV.
How to guarantee that the quality of the phone calls is always good? Thanks to QoS (Quality of Service) rules that reserve a part of the bandwith.
The word “Carrier” can refer to a part of an electric signal, but in English it also means a “wireless communication service provider” (Movistar, Pepephone…).
Own vs. hired network
Both fixed and mobile communications providers can have their own network or hire an existing one thanks to the spanish Law NEBA “Nueva Ethernet de Banda Ancha” (for fixed networks) or OMV “Operadores Móviles Virtuales” (for mobile networks).
OSI model
The Open Systems Interconnect tries to standard the communications. It consists on seven layers. The most important ones:
PHY (physical layer). It represents the voltages, the frequencies…
MAC. It represents the physical addressing. You should not change your MAC address (but you can).
In TCP/IP, this is the IP address. It depends on the network.
In TCP/IP, this is the port number. It depends on the application.
, 6 and 7. Not important for this course.
TCP/IP basic concepts
This theory is necessary for networking subjects, but also for understanding VoIP telephony (Voice over IP).
Definition: A host is any device connected to a network. A host can have one or many IP address(es).
These fields are necessary for the network configuration of any host:
IP address: The unique address of your device.
Subnet mask: It marks and separates the network (common) part of the address and host part. Only understandable in binary.
(Default) Gateway/Router: IP address of the device that connects this network to other networks (typically the internet if you are in a stub network)
DNS server(s): Hosts that provide with a database that correlates URL address and IP address. For example: www.google.es → 172.217.168.163
Difference between switch and router
<<This is a quick and dirty explanation>>
Basically, a switch connects many hosts that belong to the same network (192.168.0.1/24, 192.168.0.2/24…). It doesn’t have to have an IP address.
…while a router connects to two or more different networks.
For example, your home modem-router connects on one side to the WAN network of your ISP (83.213.53.12) and on the other side to your home network (192.168.0.1). It must have one address on each network.
Example network:
Difference between router and modem-router
A router connects two or more networks of the same standard (typically ethernet).
A modem-router also connects two or more networks, but one of them is not ethernet. It can be DSL, DOCSIS, GPON.
Network types according to their topology
Bus: Todos los equipos se conectan a un mismo canal (el llamado “bus”). Si se corta, los nodos quedan aislados. Ejemplo: IEEE 802.4 (Token bus):
Estrella: Los equipos se conectan a un nodo central “supernodo”. Gasta más cableado. Si cae el nodo central, falla toda la red. Si cae cualquier otro nodo, la red sigue funcionando sin él. Si se corta un cable, se desconectará el nodo que cuelga de él, pero el resto de la red seguirá funcionando. Ejemplos: IEEE 802.3 (ethernet sobre par trenzado) y IEEE 802.11 (Wi-Fi)
Anillo: Los nodos se conectan en círculo. Si falla un nodo, o si falla el cable en cualquier punto, dejará de funcionar todo. La diferencia es que el anillo está cerrado y el bus no. Ejemplo: la fibra óptica que recorre las ciudades está en doble anillo IEEE 802.17
Malla: Todos los nodos se interconectan. Si falla un camino, se usará otro alternativo. Es un tipo de red distribuida que combina las anteriores.
PAN (Personal Area Network): Cuando conectas un portátil a un móvil, cuando emparejas el teléfono con el Bluetooth del coche…
LAN (Local Area Network): Une equipos que estén físicamente próximos (en el mismo edificio). Las redes inalámbricas (WLAN, Wireless LAN) son un tipo de LAN.
MAN (Metropolitan Area Network): Red que se extiende en el territorio de una ciudad. Ejemplo: una pequeña empresa de internet rural, una pequeña zona de la Guifinet, un nuevo operador que empieza a funcionar en un área pequeña…
WAN (Wide Area Network): Redes que abarcan áreas extensas (países). Un ejemplo de esto es la red pública de telefonía estatal.
Some of them can be partially wireless: WLAN, WMAN. Example: Guifinet:
What is Ethernet?
According to Wikipedia: Ethernet /ˈiːθərnɛt/ is a family of computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in 1983 as IEEE 802.3.
Ethernet standards according to their media and speed
Como norma general el primer número indica la velocidad de transmisión en Mbps, la palabra BASE indica que los datos se transmiten sin modular, directamente “1” equivale a un voltaje y “0” a otro (en par trenzado se usa Manchester2).
El número del principio (10, 100, 1000): Suele indicar la velocidad de transferencia en Mbps. Ahora empieza a poner la unidad también (10G = 10 Gbps).
La palabra BASE: Abreviatura de baseband, “banda base”, que significa que los datos se transmiten sin modular, directamente 1 y 0.
El tipo o longitud del segmento: Esta parte puede ser número o letra:
Número: Abreviatura de la longitud máxima que puede aguantar el cable sin atenuar demasiado. Ejemplo: 10BASE5, el máximo son 500m. En par trenzado se pone “T” porque como norma general, ethernet sobre par trenzado tiene un alcance máximo de 100m.
Letra: Identifica físicamente el tipo de medio (ver imagen abajo).
Existen tecnologías de Link aggregation que permiten sumar el ancho de banda de varios canales .
Kinds of twisted pair cables
We have…
…for telephony/DSL:
Single pair.
Single pair in two pair cable.
Single pair in multi-pair cable (25 pairs, 50, 75…)
…for data networks but also telephony/DSL we use twisted pair:
UTP(Unshielded Twisted Pair, par trenzado sen apantallar): Non hai recubrimento de aluminio fronte interferencias. Maleable, fino e lixeiro. Sufre algo de diafonía e EMI (electro magnetic interference).
FTP(Foiled Twisted Pair, par trenzado con pantalla global). Ten un recubrimento ó redor do conxunto de pares. É unha solución entre o UTP e o STP. Rixidez intermedia.
STP(Shielded Twisted Pair, par trenzado apantallado): Ten un recubrimento metálico en cada par que mellora o comportamento fronte a interferencias. Soporta máis distancia e velocidade de transmisión. Máis caro e menos maleable. Moita rixidez.
SFTP(Screened Fully Shielded Twisted Pair). Protección máxima: apantallamento global + apantallemento de par. Rixidez máxima.
Remember to use RJ-49 plugs when shielding is present.
Categories of twisted pair cabling
CAT3. Up to 10Mbps. Irrelevant.
CAT4. Up to 16Mbps. Irrelevant.
CAT5. Up to 100Mbps.
CAT5e (up to 100MHz, 1000BASE-T, or 2.5GBASE-T). Most common.
CAT6 (250MHz, 1000BASE-T, 2.5GBASE-T or 5GBASE-T). Compulsory in ICT buildings.
CAT6a (500MHz, 10GBASE-T).
CAT7 (600MHz, 10GBASE-T).
Newer categories (7a, 8.1, 8.2…) will support above 1 GHz.
Number of wires/pairs used
As you know, UDP/FTP/STP/FTP cabling has four pairs (8 wires). The number of wires used depends on the bitrate (speed):
If bitrate is less than or equal to 100 Mbps, only 4 wires are used.
One pair will be used for transmission (Tx).
One pair will be used for reception (Rx).
If bitrate is greater than 100 Mbps (1 Gbps, 10 Gbps…), all 8 wires are used.
Two pairs will be used for transmission (Tx).
Two pairs will be used for reception (Rx).
When you use UDP cables for ICT distribution networks, they transport DSL signals (NOT ethernet), so they just use one single pair (the other three act as a reserve).
NOT INTERESTING ANYMORE: You could use the same cabling for telephone and ethernet ≤100Mbps. You just have to use the blue pair for telephone, and the green and orange pairs for ethernet.
The PoE standard
The Power over Ethernet standard allows to transport the DC necessary to power the devices. It eliminates the necessity of power supplies in certain areas.