basics of internetworking Flashcards
Computer Network
Groups of computers or other devices that use a set of common communication protocols
Nodes
devices
AKA hosts or clients
Common examples of nodes include computers, IP phones, and printers.
Links
The connections that transfer data between nodes.
wired connections or wireless connections.
example = wired connection would be the Ethernet cable plugged into the back of a computer coming from a router or modem.
OSI model
allows computer network technicians to visualize how one node talks to another node on a computer network and is helpful when it comes to troubleshooting
problems in network communication when they occur
physical layer (layer 1)
- Media (term for cables)
- physical layer = cables (hands on)
The network hub will receive input, amplify it, and output it out of all the ports on the network hub regardless of destination.
Servers
provide services to host or client nodes.
Common examples of servers include file servers, mail servers, print servers, and game servers
Protocols
set of rules that determine how data is transmitted and interpreted for a computer network.
protocols include HTTP, FTP, DHCP, DNS.
network hub
largely obsolete nowadays, having been replaced by network switches
network switch
hardware used to interconnect nodes on a computer network.
perform vital function in Layer 2 Switching to receive and transmit data to a destination node on a computer network.
router
perform traffic direction functions from one computer network to a destination computer network
bits
- Rapid pulses of activity in the signals
- Protocol Data Unit (PDU) layer 1 physical
The rapid transmission of bits in series is known as a
bitstream
each bit has an assigned value of either 1 or 0
data link (layer 2)
taking a layer 3 PDU and encapsulating it inside of a layer 2 PDU known as a Frame
common protocol = Ethernet, is used for formatting a standardized logical ordering of bits to create what is known as an
Ethernet frame.
1522 bytes.
Frame Header - a source and destination address.
Frame Footer - trailing series of bits that make up what is known as the Frame Check Sequence (FCS) field which provides a form of error detection.
(MAC) address will populate the source and destination address field in the frame header.
48-bits in length and are unique to each individual Network Interface Card (NIC) for each node on a computer network.
MAC addresses are also expressed in a Hexadecimal Format.
the switch in getting a frame from one node inside a computer network to another node inside the computer network is known as Layer 2 Switching.
network (layer 3)
- Packet Forwarding- getting packet from one node to another node
- getting packets from one part of the network to another part of the network
Packets contain a leading series of bits
Packet Header (source address and destination address)
IP provides logical address via IPv4 + IPv6
transport (layer 4)
providing delivery mechanisms to support host-to-host communication for programs
protocols -
-Transmission Control Protocol (TCP)
-User Datagram Protocol (UDP).
If TCP is in use during communication, the layer 4 PDU is referred to as a Segment.
If UDP is in use during communication, the layer 4 PDU is referred to as a Datagram.
address type used at the transport layer is a combination of the layer 3 logical address and a TCP or UDP Port Number
UDP (user datagram protocol)
This decreases latency in communication at the cost of decreasing reliability of data transmission
is known as a connectionless-oriented protocol
session (layer 5)
establish the starting point and ending point of sessions in host to-host communication via protocols.
open an individual session known as a Session Beam
presentation (layer 6)
displaying data to user of an application.
a failure= Protocol Mismatch
application (layer 7)
interfacing with the user and is the briefest in scope.
It is the closest to the end user
and allows user inputs.
bus topology
all nodes are connected via a common and shared link
all nodes receive equal priority in generating their own traffic this can causes a problem that is known as collisions
advantages
- simple design + linear architecture
- works well for small computer networks
- easy to extend w a connector or repeater (network hub)
disadvantages
∙ Bandwidth is shared among nodes and performance suffers with more nodes.
∙ All nodes receive the same traffic which causes a security concern.
∙ The entire computer network shuts down when there is a break in the main cable.
ring topology
all nodes are connected to two other nodes in a continual path where traffic passes through each node towards its destination
the traffic can be unidirectional (one way) or bidirectional (two way
token generated
Advantages of a Ring Topology
∙ Performs better than a Bus Topology under heavy load.
∙ Easy to isolate faults.
Disadvantages of a Ring Topology
∙ Latency increases with more nodes.
∙ Adding or replacing nodes can cause issues with traffic on the computer network.
star topology
every node on the computer network connects to a central piece of network equipment (network switch or router)
Advantages of a Star Topology
∙ If one node fails it does not affect the entire computer network.
∙ Nodes can be added or removed without affecting the entire computer network.
∙ Great for large computer networks.
Disadvantages of a Star Topology
∙ Can be expensive due to number of cables required for each node.
∙ The central piece of network equipment is a single point of failure.
mesh topology
all nodes connect to each other.
Advantages of a Mesh Topology
- Full redundancy means there is no single point of failure.
- Direct pathways for traffic decrease latency.
Disadvantages of a Mesh Topology
- More expensive than a Star Topology
- Requires more administrative oversight.
IPv4 addresses
IPv4 addresses are 32-bits
Dotted Decimal Notation (DDN). Each octet in an IPv4 address has a value between 0 and 255.
stateful protocol
requires an additional service to be running, like a server.
When a node is configured to obtain an IPv4 address from a server on the computer network, this is considered stateful
stateless protocol
requires no previous communication with another service to function
node is not configured to do so,it uses Stateless Autoconfiguration to generate -
Automatic Private IP Address
(APIPA)
what does the APIPA being present mean?
Automatic Private IP Address
(APIPA)
sign that there is a problem on a computer network
IPv4 address class
value of first octet = class of the address
The class of the address will determine how many octets belong to
- Network Field + the Host Field
A- 0-126
B- 128-191
C-192-223
D- 224-239
E- 240-255
127 = reserved for loopback
each octet of an IPv4 address is 8-bits even though it is written
in dotted decimal notation.
network field
cannot be altered
Internet Assigned Numbers Authority (IANA
values in the octet(s) which make up the network field are assigned by a global standards organization
host field
comprised of the octet(s) in an IPv4 address which can be altered
variables and can be changed to create unique IPv4 addresses to assign to nodes on a computer network
broadcast address
If all the host bits are represented via binary 1s
the rules of the protocol will be used as the destination address for every IPv4 node in the same network
network ID or network address
all the host bits are represented via binary 0s
host address
combination of both binary 1s and 0s
used for assignment for nodes on a computer network
subnet mask
- written in dotted-decimal notation
- further specify separation between the network field and host field for an IPv4 address
The network prefix is written in the context of the IPv4 address being a 32-bit address
public IPv4 address
an address that is routable over the public Internet
private IPv4 address
not routable over the Internet and is primarily assigned to a node on an internal computer network
network address translation (NAT)
allow prviate IP address access to the internet by router
class a private IP address range
10-10.255.255.255
class b private IP address range
172.16.0.0-172.31.255.255
configuration options
DHCP - dynamically configuring a node with an IPv4 address on a computer network (stateful protocol)
**manually **configure the node (the Default-Gateway IPv4 address, subnet mask, and DNS server)
class c private IP address range
192.168.0.0-192.168.255.255
IPv6 addresses
IPv6 address are 128-bits in total length
8 octets - 16 bits in length (aka 2-bytes)
Each octet max value between 0000 and FFFF.
Consecutive zeroes can be replaced with two colons (::)
Stateless Autoconfiguration
provides an IPv6 address automatically for itself. known as a Link-Local Address.
Hash-Based algorithm = last 64 bits of address is randomly generated
dual stacking
mechanism that allows nodes or pieces of network equipment to have both an IPv4 and IPv6 address associated to them.
Network Address Translation 64 (NAT64)
used on an external router for a computer network
tunneling
obsolete mechanism= encapsulates IPv6 packets inside IPv4 packets
protocol stack
Protocols are designed to work with one another
Protocol Layering
break up intended function of application across multiple layers of the OSI Reference Model
Hypertext
Transfer Protocol (HTTP)
a protocol used to display webpages on a browser
present at application layer
Institute of Electrical and Electronic Engineers (IEEE)
worlds largest focused on education and
advancement of telecommunications and computer engineering.
International Organization for Standardization (ISO)
people from various national standards organizations that promotes world-wide proprietary and commercial standards.
- published the OSI Reference Model.
Internet Engineering Task Force (IETF)
-development and standard settings organization for the Internet.
- Focused on standards related to the TCP/IP Internet protocol suite
secure
used to indicate the protocol includes a form of Encryption in its use
non-secure
indicate there is no mechanism for encryption involved in a protocol’s use
Internet Control Message Protocol (ICMP)
- used for troubleshooting nodes on a computer network.
- utilizes echo reply requests to determine connectivity (ping)
telnet
non-secure protocol = allows computer network administrator to remotely configure network equipment or network devices
(network switch or router usually).
Secure Shell (SSH)
**secure protocol = allows network administrator to remotely configure a network device (network
switch or router usually).
Simple Network Management Protocol (SNMP)
– is a protocol that provides mechanisms for collecting and organizing information
- capability to change configuration options + establish configuration baselines on a computer network
Domain Name Server (DNS)
protocol that translates domain names for websites to an IP addresses.
Dynamic Host Configuration Protocol (DHCP)
protocol allows node to** request** IPv4 address assignment from an external server
Dynamic Host Configuration Protocol version 6 (DHCPv6)
protocol that allows a node on a computer network to request and
IPv6 address assignment from an external server.
Network Address Translation (NAT)
protocol used to associate a private IPv4 address on a computer network with a
public IPv4 address for sending and receiving traffic over the public Internet
Hypertext Transfer Protocol (HTTP)
non-secure protocol that allows users of Internet browser to request resources in the form of web pages and other content from an external web server
Hypertext Transfer Protocol Secure (HTTPS)
secure protocol allows users of Internet to request resources in the form of web pages
Network Time Protocol (NTP)
protocol designed to synchronize all pieces of network equipment and nodes on a computer network FAST using the same Coordinated Universal Time (UTC).
File Transfer Protocol (FTP)
protocol designed to transfer computer files
fault tolerance
ithe degree to which our computer networks can suffer degradation in
operations due to some type of failure but still maintain mission capable functionality
Power Supply Unit (PSU)
component utilized to supply power to a piece of network equipment
Uninterruptable Power Supply (UPS)
battery backup unit that will continue to power equipment once the main source
of electricity feeding it has suffering an interruption.
graceful power downs, and avoiding a complete outage during a short and
sudden loss of electricity to a facility.
An UPS can be meant to serve just a few computers or multiple network switches, routers, and servers depending on the size and specifications of it.
Automatic Transfer Switch (ATS)
These are rack mounted pieces of equipment that provide another layer of fault tolerance to a communications rack setup.
high availability
prioritizes maintaining access to a system or resource on a computer network.
will deploy multiple and redundant paths to and from nodes on a computer network to ensure access in the event one of the links goes down.
backup systems
are employed on a computer network to ensure that in the event a server or critical piece of network equipment happens
to experience an outage or failure, the computer network can response and return to normal operations
Hot Spares and Hot Swapping
the ability to quickly recover from a failure on a computer network
the ability to replace a single circuit card without taking down the equipment completely becomes very beneficial
Cold Spares and Cold Swapping
pieces of network equipment that will need to be manually added to replace a piece of network equipment that has ceased to function.
- requires you to completely power down a piece of network equipment to replace it
