TCP / IP and Subnet Masking Flashcards
Tcp / ip version 4
current version of TCP / IP
TCP / IP Protocol
Is actually a protocol suite (i.e. a collection of protocols)
The main two protocols are made up of TCP and IP protocols
IP
Internet Protocol
What does IP do?
IP is the protocol w / in TCP/IP that is in controls routing of info to different comps, devices, servers.
Deals with IP addresses, subnet masks, default
Figures out where other comps are so they can begin communication.
It is a “routable protocol”
Connects computers based on the computers IP addresses
Protocol Suite
A collection of protocols
TCP
Transmission Control Protocol
Routable Protocol
makes it so you can divide comps into subnetworks with a boundary that is a router.
Go through a router to connect to other subnetworks.
Allow you to divide huge NWs into small NWs and can connect these smaller NWs with routers
NOn routable protocol
with non routable, all computers are connected
OSI Model
Basic steps of NW communication procedure.
What does TCP do?
Manages the communication process
Windowing
Process by which the client comp sends info to server comp.
The process that happens when comps are
Why was the internet created?
For the military. For WW3 scenarios. If nuclear armageddon has happened and you have diverse military installations trying to communicate with each other. This is the scenario tcp ip was created under.
Realization that communication might be flaky, if you send all info at once it might be garbled. Created “windowing” to test quality of transmission lines and sends “packets” (bits and bytes) of info. Acknowledgement is send back to sending computer to let it know packets where received. Sender will increase amount of packets sent after acknowledgment.
What does a receiving computer send to the sending computer when it receives packets?
It sends a confirmation message of data received
What does the sending computer do when it receives a confirmation of data received from its target computer?
It sends more packets than the last transmission
What does the sending computer do when there is an error in data sent?
Goes back to sending one packet at a time
What OSI layer is TCP?
Layer 4 - Transmission Layer
What OSI layer is IP?
Layer 3 - Networking Layer
IP Adresses
slj
Subnet Mask
Way to segment a NW logically so comps and devices can’t talk to other comps and devices on same NW. If you have a lot of comps and devices on your NW you don’t necessarily want them all talking to eachother
Default Gateway
the Router (can be other devices too) for the subnetwork the device that connects your subnetwork to all the other networks out there
DNS Server
Map domain names to IP addresses
What does your comp do when you enter a domain name?
It talks to the DNS and asks what the domain name means. DNS tells your comp what
Your comp will first search the local NW for the website. If it doesn’t find it it goes to the default gateway to get connected out to the website on the internet.
DHCP
Dynamic Host Control Protocol
What does your computer need to know
Comp needs to know its ip , default gateway, subnet mask , and what DNS to talk to
Static IP
Manually way to give NW info to your computer
Can take a long time if you have a lot of computers to enter info for. Problem : same info entered for two comps will cause havoc
Dynamic IP addresses
You can give your comp dynamic ip addresses:
Where DHCP comes in.
When comp connects to NW it will call out the DHCP server.
Dhcp server will then give it an IP address, tell it the subnet mask, default gateway, and DNS server.
Dhcp keeps track of addresses given out so that all addresses are unique
What does dhcp allow for?
The automatic distribution of IP addresses
It keeps track of IP adresses issued so that no two computers receive the same IP address
What happens in DHCP process?
- your comp asks for an IP address
- you have already told dhcp the scope of ip addresses it can give out. You tell it the subnet mask, the default gateway, and the DNS servers this is all preconfigured by you
- DHCP server will then give all info to comp with a “lease time”
Configured into DHCP by server admin. - Half way through lease your comp will try to renew lease on IP
- DHCP server says yes or no
- if comp can’t contact dhcp at 50% mark, it tries again at next 50% mark and continues until it gets in touch.
Contact time has a 50% “half life”.
NAT
Network Address Translation
People at first thought each comp would have to have its own ip that was unique to the world. not just your office but unique to the world. nat fixed this issue
How NAT works
each router needs own ip address. once inside router / inside internal nw , you can reuse addresses.
server on internet is concerned with the routers external ip address
Router has nat built into it. router routs info to the client comp in its network w / o nat every comp would need a unique ip address.
NATs purpose
Makes it so each computer doesnt need an absolute unique IP address
Subnet Masking
sdf
Define a Protocol
a protocol is a set of rules and procedures used for communication.
a protocol sets the rules and procedures for computers on a nw to talk to communicate
Stack definition
a “stack” of many small protocols to make up one big protocol
Analogy for NW Protocols
USPS “protocol”
Fedex “protocol”
rules and procedure to send packages and mail. Both have same basic components to their protocols (they have the same standards of communication: packaging, addressing, payment, getting package onto the network
Standard of communication for computers
the OSI Model
Purpose of the OSI Model
sets the basic standard for ALL NW communication
7 layers of the OSI model
Application Presentation Session Transport Network Data Link Physical
Neumonic saying for 7 Layers of OSI model
A Preist Saw Two Nuns Doing Pushups
Application Layer
deals with network API’s.
Gateway layer
Presentation Layer
deals with formatting for data to be sent
Session layer
synchronization between the computers
Transport layer
packet management,
where message is broken into pieces and ordered to be sent
Layer that TCP is on
Network layer
Addressing and Routing
layer that IP is on.
Router layer
Data Link layer
deals w/ data frames, like the letter you put the data into, format of the package / letter itself to go out onto the internet.
Bridge / Switch layer
Physical layer
hardware, how are we connected to the internet?
Hub / Repeater
How data travels through the OSI model
sending comp always sends data DOWN through OSI model.
receiving comp receives the data UP through the
Header
the information that each OSI layer adds to the data being sent to assist in the process of communication.
Headers are removed by the corresponding layer on the receiving side of the network
Trailer
information added to data by the Data Link layer to ensure data is not corrupted in transit
even though data travels down and up through the layers, what does each layer believe?
each individual layer believes it is directly connected to its corresponding layer.
tcp/ ip architechture based on
DARPA model
DARPA model
4 layer model,
each layer coressponds to one or more layer of OSI model
Names of
application
transport
internet
network
What layers of DARPA model correspond to the OSI model?
Application -> application, presentation, session
Transport -> Transport
Internet -> Network
Network Access -> Data Link, Physical
headers in darpa model
each layer of darpa model adds headers like in OSI model
Protocols in Application layer of TCP/IP / DARPA model
http, ftp, smtp, dns, rip, snmp
Protocols in Transport layer of TCP/IP / DARPA model
TCP, UDP
Protocols in Internet layer of TCP/IP / DARPA model
IP, ARP, ICMP, IGMP
Protocols in Network Access layer of TCP/IP / DARPA model
Ethernet, Token Ring “low level protocols”
TCP
Transmission Control Protocol
What is TCP
one to one connection between comps, connection-oriented communication, “reliable” communication
connection-oriented communication, and 3-way handshake
used by TCP. means that a connection must be established before data can be exchanged. TcP uses a “three-way handshake” to establish this connection
What is the 3 - way handshake?
- comp 1 signals comp 2 & sends info for communicating.
- comp 2 acknowledges comp 1s request and sends back info for communicating with it.
- comp 1 begins communication with comp 2
Reliable Communication
each comp sends back acknowledgement of reception of each others messages
Like sending certified mail
UDP
User Datagram Protocol
Typically used when one is trying to communicate with many,
connectionless, unreliable communications
Unreliable Communication
no acknowledgement of receipt by receiving computer. Like sending uncertified mail
analogy of UDP
radio broadcasting
Internet Layer Protocols
IP, ARP, ICMP, IGMP
Transport Layer Protocols
TCP and UDP
IP Protocol
used for addressing and routing
ARP
Address Resolution Protocol
Resolves an IP address down to the computers hardware address. Computers actually communicate based on their hardware addresses
ICMP
Internet Control Message Protocol.
Diagnostic and error reporting.
icmp will try to send error back to sender if there is an error in transmission
analogy for icmp
receive a letter back marked return to sender. letting you know there was an error in sending
IGMP
Internet Group Management Protocol.
Manages IP multicast group membership.
Multicast communication
requires membership to this group and igmp mananges this group membership
Types of tcp/ip communication
Unicast (one to one)
Multicast (one to many)
Broadcast (one to all)
Anycast (one to one of many)
how Multicast works
uses a multicast group. sends to everyone who chooses to subscribe.
Anycast
a number of comps will subscribe to an any cast address. When server sends out info it is sent to the closest of all comps subscribed
What is an IP address
a 32 bit address that is used to uniquely identify a computer on a network.
The NW ID portion of the IP address identifies the network where the computer sits.
The Host ID portion of the IP address uniquely identifies the computer on its network.
analogy for an IP address
a lot like a street address.
NW ID portion is like the name of the street.
The Host ID portion is like the house number.
Left most portion of the IP address
is the NW ID
Right most portion of the IP address
is the Host ID
Subnet Mask purpose
to determine where the division between NW and Host IDs in an IP address
What are the numbers in the Subnet Mask and what do they represent?
Subnet mask always begins with 255s on the right and ends with 0s on the right side.
255s represent the Network ID and the 0s represent the Host ID
are subnet masks required?
Subnet mask is not an optional component. An ip address will always have a subnet mask.
How to view IP configuration
Command Prompt (cmd) > type in ipconfig
How to test connectivity
Use ping (basically tries to go out an touch another comp) Command Prompt > enter ping IPaddress
What Ping does
sends out an echo request. If computer receives the request, it will send a message back. Makes 4 attempts incase there is a small hiccup on the 1st ping.
