Introduction to Networking

Intro to Networking

• A network contains at least 2 computers which can communicate, usually in a client/server relationship
• A network allows the exchange of information over a data link
• Snickernet was the predessor to the modern internet, where people shared information physically via floppy disk
• The internet is the largest network and an inter-network that connects many smaller networks
• End devices on a network are called nodes
• Infrastructure devices include routers, firewalls, switches hubs, WAPs, etc
• Protocols are the rules and communication standards controlling traffic between devices
• Switches connect computers to establish a LAN
• Routers allows passing traffic from one network to another
• Firewalls are similar to a router, working on Layer 3 to filter and manage network traffic
• Cloud encompasses some type of network media transmission

Network Overview

• Computer networks connects computers together, to provide access to services like email
• Routers provides gateway access to the network
• Media can be wired or wireless
• Clients provide users with access to the network
• Servers share its resources with other computers
• Switches and hubs provide LAN access through wired connections
• Switches are intelligent, learning and remembering MAC addresses to direct traffic efficiently
• WAPs can act as routers and switches, especially in smaller networks
• Media connects devices to the network
• Routers serve as gateways to other networks such as a WAN

Network Types

• Local Area Network (LAN): Computers in a small geographic area
• Wide Area Network (WAN): LANs over long distances
• MPLS (multiprotocol label switching)
• WLAN (wireless LAN) / WWAN connect over wireless connections (cell phones are one type of WWAN)
• Metropolitan Area Network: Larger than LAN and incorporates LANS and WANS
• Campus Area Network: Two or more LANs, multiple buildings
• Storage Area Network: Allows high speed access between servers; requires redunancy
• Personal Area Network: Primarily connects devices such as keyboards and headphones via Bluetooth

Frames & MAC

• Computing data looks like 0 or 1 in computers
• There are 8 bits in a single Byte
• Network and data rates are measured in bits and not Bytes
• 100 Mbps is 100,000,000 bits per second
• Mbps to bits = Add 6 zeros
• Gbps to bits = Add 9 zeros
• Tbps to bits = Add 12 zeros
• File sizes are measured in Bytes and are 8 times more than a bit
• For example, 350 Megabytes would be 350,000,000 or 2,800,000,000 (350,000,000 x 8) bits
• Modern packetized data networks send information in small chunks
• Frames contain payload (1500 bytes), and addressing information
• Ethernet (IEEE 802.3) is a protocol family
• WI-FI 802.11
• Ethernet performs encapsulation of frames
• A NIC (network interface card) is where Frames start and end

What is a MAC Address

• MAC Addresses get assigned to individual network interface cards
• MAC stands for Media Access Control Address
• MAC Addresses use 12 hexadecimal
• Each hexidecimal contains 4 binary bits
• MAC Addresse are 48 bits in total
• MAC addresses are hardware/physical addresses, AKA "burn-in" addresses
• The first half of a MAC Address is the Original Equipment Manufacturer (OEM)
• The last half of a MAC address is the unique identifier
• macvendors.com - look for MAC addresses and brands attached to them
• Windows can show the MAC address via ipconfig /all under physical address
• On Linux/Mac, use ifconfig
• An Ethernet frame will have source and destination MAC Addresses
• Cyclical Redundancy Check (CRC)

Hubs vs Switches

• Hubs repeat signal and have multiple ports
• All hosts connected to a hub will receive its traffic, with high risk of loops and collisions with too much traffic
• Switches keep tables of destinations, and deliver information efficiently
• Switches keep a running table of MAC Addresses
• Switches knows the destination
• Switches send traffic to the specific client that needs the information
• The first network switch was the Kalpana EtherSwitch, invented around 1993

Broadcast Domains

• Communications can be transmitted in Unicast, Multicast and Broadcast
• Unicast is when the frame is sent to a single destination from a sender to a single receiver and is most common
• Multicast goes between one or more senders and multiple receivers, which dedicates MAC addresses or a range to them
• Managing Multicast is complex and requires updated equipment

The Broadcast and Broadcast Domains

• All "F"s or 48 1's means everybody
• Every device must receive the traffic
• IP is logical and MAC is Physical (Address Resolution Protcol (ARP))
• The computer sends a broadcast, and the receiver responds with a unicast
• Broadcast storm appears as loop, and is replicated, causing network failure

Intro to IP & Routing

• The protocol for the Internet is IP
• Most prevalent is IP version 4 as part of the TCP/IP stack
• IP helps the datagrams receive Labels for source and the final IP destination
• IP relays and routes traffic across network boundaries
• IP is a connection-less service that is best effort, and does not care if the packets have arrived
• Vint Cerf and Bob Kahn invent the TCP/IP protocol suite
• 1974: Introduced by DARPA so t started within the military
• 1981: Internet Engineering Task Force (IETF) IV4 became official with it official header:
• Provides logical addressing schema for networks

The IP Address

• 32 bit in length, represented in decimal format

• It has 4 binary octets

• For example, 192.168.100.1

• In Binary: 11000000.10101000.01100100.00000001

• For example, assign each endpoint. For instance, a switch or router doesn't need an IP; however, in most cases, we assign an IP for management

• It identifies that a device is part of a broadcast domain (or network) and is called the Network ID or Subnet ID

• The use of private internet is for Private IPV4 Ranges given by RFC 1918:

• These include:

• 10.0.0.0 - 10.255.255.255 (10/8)

• 172.16.0.0 - 172.16.255.255 (172.16/12)

• 192.168.0.0 - 192.168.255.255 (192.168/16)

• A private address space allows someone to build a network at a home without having to be concern about other networks

• Public addresses are used over the internet and an ISP will possess a certain range of IP that can be assigned

Routing Packets

• IP can be a Datagram (UDP+IP=connection less) or a Packet (TCP+IP=connection oriented)
• Datagrams and Packets are often referred to as Packets
• Default gateway is the gateway to connect to other networks
• If you have an IP package that goes from one network, it become part of another network:
  • The packet gets wrapped into a frame with the destination source of the MAC address of the router. Once, the router gets the packet it will unwrap the frame and see the final destination in the packet. Because the router knows the final MAC address, the router will wrap the package in another new frame. At the end the device will get rid of everything except the payload

Real World IP Routing

• 2900 routers are known as the ISR ( integrated services router) and a generation two, where it can have different services

Address Resolution Protocol

• Resolves IP Addresses into MAC Addresses, from IETF RFC826
• For Network communication, computers will need both IP and MAC
• ARP is used to find the MAC Address when the IP Address of destination is known
• The ARP cache is the temperate collection/table of all known IP to MAC Addresses
• When using Windows, Mac OS, or Linux system use commandarp -a
• Use command show arp for Cisco systems
• Before Network communication, the computer will refer to the ARP cache and if it doesn’t have the MAC Address of the destination it will do a Arp Request
• The gratoutitous Arp is an ARP announcement to update other hosts ARP tables without the need for an ARP Requests
• Sometimes this is preformed during the system startup process.
• Helps update the network faster when the IP address changed
• The reverse address' resolution protocol IETF RFC 903

Intro to Ethernet & Switching

• Ethernet overview of IEEE 802.3: Defies hardware, cabling, and speed
• Is a family of standards and definitions as well as a protocol
• That most used
• Transmission to up to 80 km
• The fastest lan Speeds
• Storage Area Network FCoE ( Fiber channel over Ethernet )

Ethernet History

• -Created by Robert Metcalfe & David Boggs
• First prototype built to run 2.94 Mbps
• 1980: IEEE 802
• 1983: IEEE 802.3 standard -1982: First ethernet adapter (NIC) 10 Mbps, first medium Thick coaxial cable -Late 80s: Ethernet widely implemented
• 1992: 100Mpbs
• 1995: Gigabit
• 2002: 10G
• 2010:40G & 100G
• 2012- present: 200G & 400G and even terabit Ethernet

Ethernet Segmentation

• An Ethernet segment is connection between network devices on a shared medium ( same piece of wire)
• 2 Frames arriving at the same point at the same time cause a collision
• Collion domain is an network segment where only 1 device can communicate at a time
• A switch will separate the collision domains and every single port on a switch is its own collision domain
  • As routers can segregate collision domains
• Carrier Sense Multiple Access/Collision Detection (CSMA/CD ) - Was invented to prevent collisions
• Where each node listens to the wire and transmits whenever there no signal
• Duplex is is apart of every single Ethernet connection
• Throughput is the total amount of speed

Cables Used With Ethernet

• Copper: unshielded twisted pair ( UTP) of 8 cables twisted in pairs to prevent crosstalk and EMI. Up to 100 meter(328 feet)

• Cat5 up to 100mbps

• Cat5e up to 100mbps(1Gbps)

• Cat6 -1 gps, 10Gbps(only 55m)

• Cat 6e up to 10Gbps

• RJ45 Connector 8 pin connector

• Most wires are built using the b Standard from left to right orange, green-white, blue, green, brown

• there is White with color /only color. Put First the White with the color

• EXCEPT with blue, which is the opposite, B standard will be white-orange, orange, white-green, blue, White blue, green, white-brown, brown

• If you mix b standard and a standard. Create a crossover cable- Used to connect alike devices, like pc to pc

Ethernet Naming Syntax

• Naming Syntax- 100BASE-TX
• Speed of the connection 100Mbps, base Means baseband/broadband, Tx is the cable or media
• TX Means twisted pair
• 100BASETX , UTP 100 meters -100BASE-FX multimode 2000 Meters
• 100 BASE-LX sigle Model 10K
• 1000 base T gigabit Ethernet Cat5e or 6e

Cabling & Power

• Common Cable - Twisted pair cable
• When a cable is shielded, help reduce EMI but also emission from the cable itself
• T-1 crooss cable is - WAN cable , 2-Wire standard 1.544 Mbps, uses , uses 8 pin (RJ-48C) T-1/E-1/PRI, T-1 crossover
• This is a serial type of technology
• Ports, plain old telephone systems , POTs + Twisted pair cable
• rj11 connectors 6 pin
• analog phones /DSL connections
• Used to connect/ Connect Internet From the ISP-( Internet Service Provider )
• rj6
• rj 59
• Serial ,use in DCE/DTE data communication Equipment and Data termination Equipment

Common Connectors

• RJ 48 8 pins
• RJ11, like the phone connections ,6 pins -RJ21, Has 25 pair, usually seen connecting in a punch down Block -DE-9,or DB-9 -like the 1 , used on the cisco switches
• DB-25- Is a parallel cable, +Used to the be use with printers +
• DB-60 : common DTE/DCE cisco serial connection
• BNC Coaxial cable ,Like the one you see in antena
• F type is Also Coaxial , and It is the most common
• MT-RJ-Mechanical Transfer REGISTERED Jack , Is the smalest form factor
• GBIC $ SFP WAS, used for the 100 Basesx/xl
• Cisco Gigastack- - Not used Anymore
• SFP 1000 BASIL -sx /lx SP , like the One we, have Our , Ume, zayo Router:

Cabling Tools

• Cable tester: Confirm wire map, meaning if or crossover Straight
• On cable tester , You see 1 To 3 2 To 6= A crossover cable
• TDR, time Reflectometer ,or optical Domain Reflectometer
• Test+Entire Cable run To Detect, Where + Break + , Is Can Tell+ The+ Distance+, To the+ Break+ ,punch Down