Networking

Overview of IPv4 and IPv6 Networks

Organizations

  • Internet Society - ISOC
  • Internet Engineering Task Force - IETF
  • Internet Architecture Board, IAB
  • Internet Engineering Steering Group - IESG
  • Internet Corporation for Assigned Names and Numbers - ICANN
  • Internet Assigned Numbers Authority - IANA

Standards

  • IEEE LAN Standards 802.

International Telecommunications Unions

The ITU promotes and globally coordinates the use of the radio spectrum through standards and regulation.

  • H Series (e.g., H.323 - VoIP)
  • V Series (e.g., V.9)
  • X Series (e.g., x.509 - SSL)

United States

The National Telecommunication and Information Administration NTIA

Ohio

OSI (Open Systems Interconnection) Layers

A conceptual model in which communications between a computing system are split into seven different abstraction layers

Diagram of the OSI Reference Model

Layer 1 - Physical

Most closely associated with the physical connection between devices. The physical layer provides an electrical and mechanical interface to the transmission medium (e.g. CAT5 cabling, SMF fiber).

Ethernet can travel 100m max distance.

Hardware

  • Repeaters
  • Extenders
  • Hub
  • Bridges

Layer 2 - Data Link

This layer is responsible for the Physical Address

Network Interface Card & Media Access Control

  • Hardware address, MAC address is burned into the NIC
  • MAC Address (Media Access Control ; 48-bits binary (written in hexadecimal))
    • 24-bits, first 3 hex numbers vendor identifier (OUI)
    • 24-bits, serial number

NIC Properties

  • Speed
    • Manually set or auto-negotiate
    • mbps (megabits per second)
  • Modes
    • Simplex - One-way communication
    • Duplex - Two-way communication
      • Full duplex - simulatenaous send and receive
      • Half duplex - one sends, other receives
  • Wake on LAN

Operating at Layer 2

Hardware Protocols Software
Ethernet switch Ethernet
NIC, Network Interface Card

Hardware -

  • Switches - Concerned with connecting individual computers together
  • Switches can example the layer 2 header information on incoming packets and only forward those packets to a specific port
  • Intellegence - this physical port is connected to that physical computer
  • Switches (1) reduce noise on the network, reduce collisons; thus, improve performance and increase available bandwidth Improves security by only sending packets to specific machines, not all

Two types: managed and unmanaged

Unicast (one device)
Broadcast (all devices)

Ethernet Frame Diagram Ethernet Type field, values?

Performance Issues

  • Broadcasts (interruptions)
  • Server Saturation ()
  • Bottleneck (slow connection between devices)
  • Router latency
  • Security filtering (firewall, packet inspection)

Switches use MAC Addresses

  • VLANs reduce broadcast domains
  • Switches analyze destination header of a frame and only route the packet out of the appropriate port, not all ports like a hub
  • ‘Backbones’ connect switches together

hierarchric structural diagram of core, distribution, and access switches Core switches 10x faster than access switches

lowest port cost

Spanning Tree algorithm 802.1 s

  • root switch selection (root switch, forwards all ports) BPDU frames
  • best path selection

converged

STP self-healing capability Port mirroring

VLAN

  • bandwidth conservation
  • security benefits (only aware of devices in their own VLAN)
  • separation of a switch to segregate broadcast domains
  • Static VLANs (port-by-port basis)

ARP request?

802.1q “tag” a frame VLAN tag, inserted between the source | protocol type tags only seen between switches VLAN trunk port - switch to switch connection frames queued in a buffer to go out the trunk port QoS - for example to voice priority order

IEEE 802.1ax and the link aggregation protocol

Layer 3 - Network Layer

  • Logical Addressing (IP Address; software addressing)
  • Routing (TCP/IP)
  • Prioritization

Operating at Layer 3

Hardware Protocols Software
Router IP
ICMP
Routing

Hardware -

  • Routers - Concerned with connecting networks together.

Routers determine the best route for transmitting data. Do not forward broadcast packets. Routers can communicate with each other and exchange networks that each know s about

Layer 4 - Transport

  • Error handling
  • Chunk large data into segments
  • Port number of application

Operating at Layer 4

Hardware Protocols Software
TCP
UDP

Layer 5 - Session; not used very often

  • Session management (conversations)

Operating at Layer 5

Hardware Protocols Software
RDP

Layer 6 - Presentation; not used very often

  • Format conversions (ASCII to another format)

Layer 7 - Application

Sits just below the OS. Supports user applications

Operating at Layer 7

Hardware Protocols Software
HTTP
FTP
SMTP

Cabling

UTP cabling: unshielded twisted pair Cat 6 - 10 Gbps up to 50 m (this is what we’re using in the SOCC) Numbering System - both ends of fixed horizontal

Cat 5e Cat 6 Cat 6a Cat 7

Ethernet Nomencalture

10Base-T

10 = Mbps Base = T = Type of cabling (in this case, UTP ; twisted pair)

100Base-TX (X = full duplex)

1000Base-SX (Gigabit Ethernet, S = short waveligth over fiber)

10GBase-SR (Cat 6a for datacenters)

40Base-SR4 (almost , fiber)

100Base-SR10 (fiber)

Wifi

radio waves, rather than wired devices light socket, refrigerator, and expanding wireless clients

  • IEEE 802.11 standard
  • wifi alliance (certify compliance with IEEE standards)

Access point = attena to read radio waves

(Access Point, as translator) 802.11 wireless side, 802 on LAN side

root/infrasture mode for AP

  • lightweight AP - uses a WLAN controller software
  • Enterprise networks

RF is physical layer of wireless SSID (Service Set Identifier) = differentiates WLANs

wifi - frequency bands 2.4 Ghz or 5Ghz RF bands (unlicenses by FCC) 2.4gHz (11 channels are 5 gHz apart, thus 3 non-overlapsing 1, 6, 11)

802.11a is 5Ghz band National infrasture bands (4 non-orverlapping channels per band) (range is less than 2.4 Ghz) (supports more clients in an area)

Transmission speeds

  • 11 Mbps (b)
  • 54 Mbps (a)
  • 54 (g)
  • 600 Mbps (n, 2009) 2.4 & 5Ghz == Mimo
  • 6.7 Gbps (ah, 2011)
  • 6.9 Gbps, 5Ghz only(ac, 2016)
  • 10Gbps (ax, 2019)

Transmission width

  • 20 Mhz
  • 802.11n - double wide - 40 Mhz
  • 802.11ac - MIMO 8 streams - 160 Mhz wide

Wifi Discovery Tools

  • Beacon Frame - sent from AP to advertise itself to wifi clients
  • Wireless Diagnostics on MacOS

WLAN Security

  • ? auth

WLAN Authentication

  • Open /
  • 802.11i (user auth) (Preshared-Key or 802.1x/ EAP, extensible authentication protocol)

WLAN Encryption

  • WEP (wireless encryption), don’t use
  • AES-CCMP (advanced encryption standard), WPA2 certification
  • TKIP (temporal key ccc protocol), WPA certification

WLAN Performance

  • RF physical layer
    • (microwaves, cordless phones) - interference
    • Environment (walls brick, people)
    • distance from AP
    • number of clients

References https://www.electronics-notes.com/articles/connectivity/wifi-ieee-802-11/standards.php

https://www.digitalairwireless.com/articles/blog/what-is-a-wireless-bridge

https://www.cablesandkits.com/learning-center/autonomous-vs-lightweight-access-points

IP Addressing and IPv4 Subnetting

Logical Addressing (Layer 3) IP, Internet Protocol Addressing Methods - https://en.wikipedia.org/wiki/Anycast IP is binary. (8 bits of binary in octets, 32 bits in total) - 0 - 255

Dotted Decimal Notation

IPv4 uses 32 bits of binary in total. 8 bits of binary are grouped into octets, separated by a decimal. This format is known as dotted decimal notation. Adding up all bits in each octet equals 255; thus, the range of values for each octet is 0 - 255.

diagram of dotted decimal notation illustrating the grouping structure and a basic calculation

Classful Addresses

C

Reserved IPv4 Addresses

Loop-back can be used to check if the IP stack is functioning Ping yourself! (16 million addresses)

Interface, all 0 bits (network name) Inferface, all 1 bits (broadcast address)

APIPA (automatic private IP address) 169.254.c.c

Private Addresses (also reserved)

Class A private (10.0.0.0) Class B private (172.16.0.0) Class B (192.168.0.0)

Network Mask

‘mask off’ the network part of the address (using 11111111.x.x), reducing the number of bits available for host addresses
Class Binary Mask Decimal Mask Prefix
A 11111111.00000000.00000000.00000000 255.0.0.0 /8
B 11111111.11111111.00000000.00000000 255.255.0.0 /16
C 11111111.11111111.11111111.00000000 255.255.255.0 /24

Often converted to a decimal mask 255.0.0.0 or /8

the network mask differentiates the ’network’ bits of an IPv4 address, leaving the remaining bits to calculate hosts addresses.

Network Prefix Class A /8 Class B /16 Class C /24

Can I use the switch (i.e. packet destination is in the same network) Do I need to use a router? (i.e. on another network)

Binary Numbering
Bit Position 8 7 6 5 4 3 2 1
Binary Power 2⁷ 2⁶ 2⁵ 2⁴ 2³ 2² 2¹ 2⁰
Decimal Value 128 64 32 16 8 4 2 1
e.g., calculation 0 0 0 1 0 0 1 0 = 18

Classless addressing

CIDR (classless interdomain routing)

IPv6

128-bit address space Does not use Decimal Notation, Uses Hexadecimal addressing no subnet mask, uses prefix only

representational depiction of the hexidecimal groupings of an ipv4 address

Subnetting

bit budget and binary tables subnetting table

4 key subnet addresses

Key Address Binary
Subnet 00000000
First 00000001
Last 11111110
Broadcast 11111111

IP subnet calculator

Network Planning

Implementing a network requires an understanding of the business units and the potential for growth of the network in each segment.

TCP, UDP, Maintenance Protocols

Layer 4 Flow Control TCP / UDP

Transmission Control Protocol User Datagram Protocol

Voice and Video (speed is import) FTP (speed not as important, )

Connection Classes

  • Connection-Oriented (reliability)
  • Connection-Less (speed) [no logical session]

Connectino

Client - initiates connection Server - Accepts request

Connection - Transfer - Disconnect

Port Numbering

Port Ranges
Well Known 0- 1023
Registered 1024 - 49151
Dynamic (Private) 49152 - 65535

service multiplexing (multiple applications) 2 byte field - TCP Header

Sockets

Sockets are a combination of IP address and Port number. Sockets allow proper routing and communication of network packets

NAT

Router

Router rewrites the TCP/UDP header to allow private IP addresses to travel to the public internet.

NATing allows multiple devices on the private network to use a single public IP address for communications. In the early days, each private device had to have a corresponding public IP address (which is expensive and overwhelming)

NAT Table

NAT uses Sockets for

NAT table is only updated when packets go out

Support and Management Protocols

  • ARP -> method of determining the MAC address associated with a particular IP address, hardware device identification
    • Address Resolutoin protocol
    • command line

diagram of an ARP message

  • IGMP
    • Internet Group Management Protocol
    • Frames sent to multicast address and the group receives it

  • SNMP
    • Simple Network Management Protocl
    • Agents - collect statistics about devices
      • utilization, throughput,
    • SNMP Management station/Console
      • HP Openview
      • IBM Travolly

  • DNS
    • domain name system
    • NS.1 = authoritative DNS servers
    • DNS Namespace (IANA)
      • root
      • TLD e.g., .com
      • subdomain - globalknowlwdge.com
      • hostname - server1.globalknowledge.com
      • FQDN -

  • FTP
  • Telnet
    • Terminal emulation
    • Configure router and switches

Header Type codes (08 06, for ARP)

Routing and Wide Area Networks

Layer 3 - network layer

  • one network to another
  • one subnet to another
  • one vlan to another

Note:

  • routers sit on the edge of a domain
  • layer 2 broadcasts are not forward by routers

Referred to as ’logical segmentation’

Routing metrics - best pathway

  • bandwidth (higher bandwidth is better)
  • hop count
  • reliability
  • arbitrary cost/weights
  • delay

Routing Protocols

  • RIP
    • RIP - Distance-Vector protocol (uses hop count, or number of routets)
    • distance-vector
    • Maximum 15 hops
    • Not suitable for enterprose networks

  • OSPF (open shortest path first)
    • interior gateway routing protocol
    • Link-state routing protocol
  • EIGRP
    • Enhanced Interior Gateway Routing Protocol
    • Enterprise network ready
    • distance-vector & link-state
    • AD -> administrative distance []
  • Border Gateway Protocol (BGP)
    • exterior routing protocol
    • connects between multiple autonoumous systems

Configuring Routers

  • IP addresses for each interface
  • Which routing protocol
  • security features
  • user/password

WAN

Connecting LANs together. Point to point circuits. ELINE, ELAN

Packet-switching technology (carries packets) x.25 frame relay ATM MPLS

  • customer edge router
  • label edge router
  • label switching router
  • label switched pathway

MPLS labels

  • label , need a diagram

carrier ethernet https://en.wikipedia.org/wiki/Carrier_Ethernet

  • “metro ethernet”
  • dynamic bandwidth, pay-as-you-go

UNI - user network interface, customer demarkcation point evc - ethernet virtual connection ovc - operator virtual connection cen - enni - extended network network interface

E-Line

  • point-to-point
  • hub and spoke
  • Ethernet Virtual Private Line or E-Line: a service connecting two customer Ethernet ports over a WAN.

E-LAN

  • multi-point to multi-point
  • Ethernet Virtual Private LAN or E-LAN: a multipoint service connecting a set of customer endpoints, giving the appearance to the customer of a bridged Ethernet network connecting the sites.

EVP-LAN

  • Service multiplexing extension of the E-LAN service

EP-LAN

  • Single UNI at every customer site
  • Provides transparent LAN services

[Internet WANs]

  • Residential (oversubscribed, no reliability)
  • Small Business ()
  • DIA - direct internet access - service-level agreement

Circuit-switching (carries 0,1 bits) T1 TDM - time division multiplexing SONET - synchronous optical networking

  • sts
  • oc - optical carrier
  • dual fiber ring for fault-tolerance

OC 768 OC 1 OC 192 OC 3

Optical Transport networks

  • IP traffic (packets)
  • g.709
  • OPU - optical payload unit
  • optical data unit
  • optical transport unit

Web Protocols

Email (user@domain.name)

  1. user presses send on their email client
  2. email is sent to their local email server
  3. local mail server performs a DNS lookup to find the IP address of the receipiants mail server
  4. local mail server forwards message to receipients mail server
  5. receipiant mail server extracts the username and places the mail into a folder on the receipent mail server
  6. receipant user grabs their messages from their mail server

SMTP

simple mail transfer protocol only service to send outbound email port 25

POP3 & IMAP4

used to retrieve email from a mail server to the client

POP3 - post-office protocol “moves” the mail from the server to the client once obtained, removed from server port 110

IMAP4 - internet message access protocol “copies” the mail from the server to the client port 143

Instant Messaging

SIMPLE

SIP for instant messaging and presnce leveraging extensions

RFC 3428 IETF RFCs

XMPP Extensible Messaging and presense protocol RFC 3920

VoIP Voice over IP

Voice is digitized into packets and transmitted across the internet PBX (private branch express)

SIP RTP

SIP

Session initiation protocol

  • multimedia session

SIP sets up the connection RFC 3261 https://www.ietf.org/rfc/rfc3261.txt

Request/Response SIP proxy (sip server that tracks the IP of each phone)

RTP

Real-time transport protocol carries voice packets

150 ms or less to eliminate jitter

RTP restores the temporal order of each packet each packet contains about 20 ms of voice data

Media Gateway

Used to translate VoIP to the public telephone swithch system

H.323 https://www.packetizer.com/standards/ ITU protocol

MGCP Media gateway control protocol

Unified Communications

Multiple tech into a single platform

Remote desktop protocls

RDP (Remote Desktop Protocl), windows ICA (Independent Computing Archtiecture), citrix RFB (Remote Frame Buffer)

FTP

File transfer protocol

Malware

  • RATs (remote access trojans)
  • Keylogger (records keystrokes)
  • trojans (appears to be beneficial, but cloaks )
  • spyware (monitors user behavior)

Authentication

Verify the identity of a user

  • RADIUS
  • Kerberos (MIT, Microsoft Windows server)
  • PAP
  • CHAP
  • TACACS

credentials

Proof of identity

  • factors (or factiods)
    • something you know (maiden name)
    • something you have (cards, token)
    • something you are (retinal scan)

Firewall (edge devices, perimeter)

  • Packet filter (packet header examination, IP address)
  • proxy server (intermediary)
  • SMLI (stateful multi-layer inspection) - stateful inspection and deep packet inspection
  • UTM (unified threat management | combines above)
  • personal firewall (on the device connecting to a network)

Hardware

  • Port
  • IP
  • VPN Concentrator
  • Honeypot
  • Content Filter (can analyze packets)

Software

  • application
  • Usually only port based
  • controls internet access per application

Intrusion detection systems

  • IDS (intrusion detection system) -> monitor logs and report to security professionals
  • IPS (intrusion prevention system) -> can take action by updating firewall rules during an identified attack

Improved Wireless (https://www.wi-fi.org/)

  • WiGig, 60 GHz band, under 10m distance. Cable replacement technology
  • HaLow, 802.11ah , 950mhz , low-power wireless connections for IoT
  • BLE (bluetooth low energy), 2.4ghz band, only sends small packets to data
  • 5G, new antenna technologies, download speeds of up to 10 gbps

Software Defined Networks

Separates control plane from network/switching plane. Remote network devices can pull their configuration from a central control plane device, removing the need to configure each switch individually. This also allows for rapid response to changing network conditions by updating a single control place device.

diagram of software device network application layers

Open Networking Foundation

Power over Ethernet (PoE)

802.3bt

On-premise Network Controllers

Wireless backhaul - Communication is tunneled back to the controller

  • control plane (instructions, rules, lanes of traffic, stop signs)
  • data plane (actual data)

Cloud-based Network Controllers

Backhaul - https://en.wikipedia.org/wiki/Backhaul_(telecommunications)

Access points report back to a virtual controler in the public cloud

Last modified February 16, 2024: something (d425368)