Chapter 4 Flashcards
network protocols
Network Protocols are rules used by networks to transfer data
protocol suite
Protocol suite is a series of related protocols in which each protocol performs a separate function or a set of related functions and multiple protocols are combined in order to transfer data
subprotocol
Each of the individual protocols within the protocol suite (ex. TCP and IP) are known as a subprotocol
What is TCP/IP?
TCP/IP is a routable protocol suite
routable protocol suites
Routable protocol suites are capable of spanning more than one
network segment … they support routing
non-routable protocol suites
Non-routable protocol suites (older technology) can be used to communicate within a network but CANNOT be used to communicate with other networks
Non-routable protocol suites are not able to communicate with routers – the mechanism used to communicate with other networks
host
In TCP/IP terminology, the term host means the same as the term node in general network terminology
(A device (computer, printer, etc.) that is directly connected to the network)
TCP/IP is open, rather than proprietary
it is not owned
by any company and therefore does not require a license for its use
TCP/IP and OSI
TCP/IP implements all layers of the OSI model; however it does not implement OSI with a one -to-one correlation between TCP/IP sub-protocols and the OSI model
TCP/IP combines the functions performed by layers of the OSI model into its own layers
It is important to note that TCP/IP does not eliminate any of the functions defined in the OSI model; it combines functions of multiple layers into a single TCP/IP layer
TCP/IP core protocols
TCP/IP core protocols function at the Transport and Internet (OSI Network layer) and provide basic services to protocols in other layers
Core protocols are generic in that they support all types of applications (Application layer) and physical networks (Network Interface layer)
transmission control protocol (TCP)
Transmission Control Protocol (TCP) operates at the transport layer of the OSI model and provides reliable delivery of data from sender to receiver
(Connection oriented transmission)
TCP functions
Breaking transmission into packets (known as datagrams in TCP/IP) at sender and putting packets back together (including re-sequencing) at the receiver
Error detection and correction to insure that all packets have been received
Use of sending and receiving port numbers to insure that data is sent back and forth between the correct application process running on each computer
Flow control to adjust speed to transmission to the capabilities of the network
datagrams
packets in TCP/IP world
User datagram Protocol (UDP)
User Datagram Protocol (UDP) operates at the transport layer of the OSI model and supports applications that DO NOT require guaranteed delivery of all packets
(Connectionless transmission)
EX: live video and audio transmissions
More efficient than TCP
Internet Protocol (IP)
Internet Protocol (IP) manages the overall movement of data from the sender to the receiver
Functions include managing address translation and routing
IP makes a best effort to deliver the datagrams; determining if they were all delivered properly is the responsibility of TCP
IPv4
IPv4 (version 4) has been in use for over 30 years and is the standard for most networks and transmissions
Contains multiple problems with the most serious being limitation on the number of available addresses resulting in IPv4 being unable to meet the demands for the large number of networks and hosts on the Internet
IPv6 (IPng or IP Next Generation)
IPv6 (aka: IPng or IP Next Generation) was released in 1998 and addresses many of the problems of IPv6
Supports a virtually unlimited number of addresses through the use of a new addressing scheme
Internet Control Message Protocol (ICMP)
Internet Control Message Protocol (ICMP) provides the sender with information about the success or failure of data delivery
Delivers Acks and Naks to the sender
Reports when data fails to reach destination due to time outs during transmission (taking too long to reach a destination) or other problems
Provides information that can be used to troubleshoot network problems but does not solve the problems
Internet Group Management Protocol (IGMP)
Internet Group Management Protocol (IGMP) manages multicasting for IPv4
multicasting
Allows one host to send data to a defined group of hosts (as opposed to broadcasting which sends to all connected nodes)
Address Resolution Protocol (ARP)
Address Resolution Protocol (ARP) converts logical addresses (IP Address) into physical addresses (MAC addresses)
ICMPv6 (version 6)
ICMPv6 (version 6) is used with IPv6 to perform the functions performed by ICMP, IGMP and ARP in IPv4
TCP/IP physical address
known as MAC address
physical delivery of data
The Physical layer function that delivers the frame to a computer or other device
IP Addresses (TCP/IP logical addresses)
IP Addresses (TCP/IP logical addresses) are assigned to a node and can be easily changed if the functions on the node are moved to another node
IP addresses must be translated into MAC address for the actual physical delivery of data
implications of using IP address to identify computer
IP addresses are independent of MAC addresses
IP addresses can be moved from one computer to another
NICs can be changed without affecting IP addresses
what does the IP address identify?
The IP address identifies the network on which a host resides and the host within the network
structure of the IP address
Dotted decimal notation
consists of 32 binary bits
each of the numbers in the dotted decimal notation is known as an octet
EX: 00110110 11000110 01101100 00001101
54 . 198 . 108 . 13
The bits on the left side of the IP address represent the address of the network and the bits on the right hand side represent the address of the host
The dividing line between which bits are network and which bits are host varies under different circumstances
octet
Each of the numbers in the dotted decimal notation is known as an octet
subnet mask
The subnet mask (which accompanies an IP address) determines which positions of the IP address are network and which positions are host
The subnet mask is also a 32 binary number that is represented in dotted decimal notation
Positions in the subnet mask that contain binary ones (1) represent positions in the IP address that are network
Positions in the subnet mask that contain binary zeroes (0) represent positions in the IP address that are host
the network portion of the IP address
The network portion of the IP address must be
the same for all devices on the same network
the host portion of the IP address
The host portion of the IP address, and therefore the entire IP address, must be different for every host on the network
a host address of zeros
A host address of zeroes (the host portion of the IP
address; not the entire IP address) is the address of
the network itself.
a host address of all 1s
A host address of all 1s (in every host address position) is reserved for broadcasts
broadcasts
A broadcast is a transmission that is sent to all nodes on a network
number of potential hosts on any network
RULE: number of potential hosts on any network is maximum number of hosts values minus 2 (all zeroes and all ones)
every packet requires 128 bits of address data
source IP address 32 bits
source subnet mask: 32 bits
destination IP address: 32 bits
destination subnet mask: 32 bits
class addressing
a scheme known as class addressing was developed that allowed subnet masks to be determined from the contents of the IP address and therefore made it unnecessary to transmit the subnet mask
(This scheme does not eliminate the need for subnet masks; it allows it to be determined and therefore not transmitted.)
how class addresses work
Class addresses use the first octet of the IP address to determine what subnet mask to use
Class A addresses are addresses where the first octet is in the range from 001 to 126
Class A addresses are automatically assigned a subnet mask of 255.0.0.0
class A addresses
Class A addresses are addresses where the first octet is in the range from 001 to 126
Class A addresses are automatically assigned a subnet mask of 255.0.0.0
There are only 126 Class A addresses (001 to 126)
These addresses are assigned to many of the organizations that founded the Internet
class B addresses
Class B addresses are addresses where the first octet is in the range from 128 to 191
Class B addresses are automatically assigned a subnet mask of 255.255.0.0
These addresses are primarily assigned to ISPs and large organizations
class C addresses
Class C addresses are addresses where the first octet is in the range from 192 to 223
Class C addresses are automatically assigned a subnet mask of 255.255.255.0
IPv6 addressing
IPv6 addressing uses a 6 sixteen bit fields (a total 128 bits) as opposed to the 32 bit addresses in IPv6
represented ass hexadecimal values separated by colons
consecutive zeros are represented with double colons (::) (Can only occur once within the address)
leading zeros are eliminated
Each TCP/IP host on a network would need the following information:
IP address that is unique to that network
IPv4 Subnet Mask to be used to interpret the IP Address
Other TCP/IP information such as the address of the router to be used to communicate with other networks
static assignment
requires manual settings on the host
dynamic assignment
uses a service on the network (primarily DHCP) to automatically assign addresses and other TCP/IP information
Dynamic Host Configuration Protocol (DHCP)
is the mechanism currently used for dynamic address assignments
One or more hosts on the network are designated to function as DHCP servers
Can be a stand-alone device or a function running on a server or other host
leased IP addresses
DHCP assignments expire when a node disconnects from the network or after a set period of time (DHCP lease time)
When the lease is terminated, the assigned IP address is put back into the pool of IP addresses and is available for another assignment
IPCONFIG
The IPCONFIG command (issued at the command prompt) can be used to manage DHCP settings
/all
/release
/renew
reasons for using DHCP
Reduce the effort required to manage TCP/IP (especially address assignment)
Reduce the potential for errors when assigning IP addresses and other TCP/IP information
Enable the movement of nodes without having to reconfigure TCP/IP since node will be assigned TCP/IP info upon reconnection to the network
Make IP addressing transparent to users
Large networks can have multiple DHCP servers for load sharing and redundancy
DHCP server can be on another network allowing ISPs to use DHCP to assign IP addresses and other information to their subscribers
Automatic Private IP Addressing (APIPA
Automatic Private IP Addressing (APIPA) will assign an IPv4 address if DHCP server cannot be access or is not functional
IP address is in the range 169.254.0.0 thru 169.254.255.255 with a Class B subnet mask of 255.255.0.0
This address range IS NOT on your network but is part of a second network containing only devices with APIPA assigned addresses
Other TCP/IP information such as the address of the default gateway (router) is not assigned
APIPA address can only be used to communicate with other network nodes in with 169.254.x.x addresses assigned by APIPA and communications with other networks will not function since default gateway address is not assigned
how sockets are used
Transport layer on sender determines the port number for the destination process and includes the port number in the Transport layer header
Transport layer on the receiver uses the port number in the Transport layer header to direct the transmission to the appropriate process
registered ports
Registered Ports (1024 - 49151) are assigned to network users and process
dynamic ports
Dynamic ports (a.k.a. private ports) (49152 – 65535) are open for general use
Application developers can assign one of these port number to an application and then program the application to use this port number
Issues with using IP addresses to identify the source or destination of a transmissions:
IP addresses are assigned to host on a network; if the host (ex. a web server) is moved to another network (ex. changing the ISP that hosts your web site), then the host will get a new IP address
If a function (ex. an e-mail server) is moved to a different computer, then that function will have a different IP address (the IP address of the computer that the function was moved to)
Addresses are not “human friendly” and are hard for people to remember
TCP/IP names
Names can be used to identify a host on a network instead of the IP address for that host
Names are independent of the physical network on which the host resides
Names are human friendly
Names must be resolved to addresses before transmission can occur
Fully Qualified Domain Names (FQDN
Fully Qualified Domain Names (FQDN) also known as Fully Qualified Host Names (FQHN) identify a host using a host name and a domain name
FQHN consist of a series of character strings (labels) separated by periods
Label on the left [mail] always identifies the host or function
Component on the right is known as the top-level domain (TLD)
domain names
Domain names are associated with an organization (company, school, government body, association, ISP, etc.)
host names
Host names are assigned to individual hosts within a domain
ICANN
ICANN (the Internet naming authority) is responsible for registering domain names
second level domain
labels between the host name on the left and the TLD on the right are known as the second level domain and identify the organization
Second level domain names can be a simple single label [rmu] or a complex hierarchical structure such as show below
HOSTS file
A text file that contains host and domain names and corresponding IP addresses
The first place that TCP/IP looks when resolving a name is on the HOSTS file on the sending host
If an entry is found on the HOSTS file, then this IP address will be used and no further attempt at name resolution will be made
Domain Name System (DNS)
Domain Name System (DNS) is a TCP/IP application layer service that resolves domain and host names in IP addresses
componenets:
resolvers
name servers
resolvers
component of dns
Resolvers are hosts (any host) that require the resolution of domain names
name servers
component of dns
Name servers are a hierarchical set of servers that contain names and their associated IP addresses
second step in DNS name resolution
The first step in DNS name resolution (after the HOSTS file is checked) is to check the LAN DNS server which is the server that contains names for your domain
For individual computers who have a registered name or for networks that do not have a lot of names, the DNS local server is most likely to be at an ISP since there would be no need for a LAN DNS server in these situations
third step in DNS name resolution
When an LAN DNS server is queried and the name cannot be resolved on this server, then the resolution request is forwarded to the ISP’s DNS server
An ISP’s DNS server would most likely have the names for all networks attached to this ISP and would then resolve these names without having to forward the request to the Internet
fourth step in DNS name resolution
When a name cannot be resolved at the ISP level (or if the network is directly connected to the Internet and cannot resolve the name on its in-house DNS servers) then the request is
forwarded to DNS servers on the Internet.
The Internet consists of a series of root DNS servers each of which contains names for a specific domain suffix (ex. .COM root servers, .EDU roots servers, etc.)
root DNS server
The Internet consists of a series of root DNS servers each of which contains names for a specific domain suffix (ex. .COM root servers, .EDU roots servers, etc.)
The contents of root DNS servers can be:
The actual name to be resolved and its IP address
The domain name for a network (ex. rmu.edu) and the IP address of the DNS server (ISP or local) that contains the names for this network
Dynamic DNS (DDNS)
Dynamic DNS (DDNS) dynamically updates the DNS system when a host’s IP address changes
Telnet
Telnet is a terminal emulation protocol used to log onto remote
hosts using the TCP/IP protocol suite
Hosts
Each device on a TCP/IP network is known as a host. A host can be a computer
(a device that is capable of processing data) or a terminal
terminal
terminal (a device that does
input and/or output but no processing of data).
terminal emulation
Terminal emulation is the ability to make one computer or terminal, typically a PC, appear to look like another, usually older type of terminal so that a user can access programs originally written to communicate with the other terminal type.
FTP (File Transfer Protocol)
FTP (File Transfer Protocol) is used to send and retrieve files.
TFTP (Trivial File Transfer Protocol)
TFTP (Trivial File Transfer Protocol) is used to send and retrieve files but does not guarantee delivery
NTP (Network Time Protocol)
NTP (Network Time Protocol) is used to synchronize the clocks of computer on a network
PING (Packet Internet Groper)
PING (Packet Internet Groper) is used to test the functioning of TCP/IP and determine the ability to connect with another host
