OSI layers and protocols
Name the OSI layers.
"All Pros Search Top Notch Donut Places" - Application, Presentation, Session, Transport, Network, Data Link, Physical.
Name the TCP/IP layers.
"All Top Notch Donut Places" - Application, Transport, Network, Data Link, Physical.
Devices and protocols associated with the Physical layer in the OSI model.
(D) Hub (P) Ethernet.
Devices and protocols associated with the Session layer in the OSI model.
(D) Logical ports (P) RPC, SQL, NFS, NetBIOS names.
Devices and protocols associated with the Network layer in the OSI model.
(D) Routers (P) IP/IPX/ICMP
Devices and protocols associated with the Data Link layer in the OSI model.
(D) Switch, bridge (P) WAP, PPP, SLIP
Devices and protocols that reside in the application layer in the OSI model.
(D) User applications (P) SMTP
Devices and protocols that reside in the presentation layer in the OSI model.
(P) jpeg/ascii, ebdic/tiff/gif/pict.
TCP header size:
20 bytes
UDP header size:
8 bytes
Function of Session layer in the OSI model.
Allows session establishment between processes running on different stations.
Which layer in the OSI model "maps" to the TCP/IP model?
Application, presentation, session -> Application.
UDP use by other protocols:
DNS, DHCP, TFTP, NTP, SMTP, SNMP, LDAP(S), RIP, VoIP.
Examples of jobs in the Physical layer in the OSI model.
Data encoding, physical medium attachment, transmission technique, baseband or broadband, physical medium transmission bits and volts.
Nickname for application layer in OSI model.
End user layer
Function of Transport layer in the OSI model.
Ensures that messages are delivered error-free, in sequence , and with no losses or duplications.
Examples of jobs in the Data Link layer in the OSI model.
Establishes and terminates the logical link between nodes, frame traffic control, frame sequencing, frame acknowledgment, frame delimiting, frame error checking, media access control.
What protocols are used in the Network Interface layer in the TCP/IP model?
Ethernet, Token ring, frame relay, ATM.
TCP use by other protocols:
FTP, SSH, Telnet, SMTP, DNS, HTTP, POP, NetBIOS, BGP, HTTPS, LDAP(S), FTP over TLS/SSL.
Function of presentation layer in the OSI model.
Formats the data to be presented to the Application layer. It can be viewed as the "Translator" for the network.
Nickname for the Data Link layer in the OSI model.
Frames ("envelopes", contains MAC address,) NIC card - switch - NIC card
How does UDP function?
It is a minimal, message-oriented transport layer protocol. UDP provides no guarantees to the upper layer protocol for message delivery and the UDP layer retains no state of UDP messages once sent. Nickname "Unreliable Datagram Protocol".
UDP handshake:
No handshake (connectionless protocol)
Nickname for Network layer in the OSI model.
Packets, ("letter", contains IP address)
Examples of applications or services that are in the application layer.
Resource sharing, remote file access, remote printer access, directory services, network management.
TCP handshake:
SYN, SYN-ACK, ACK
Function of application layer in OSI model.
Serves as the window for users and application processes to access the network services.
Nickname for the presentation layer in the OSI model.
Syntax layer - encrypt and decrypt.
Nickname for Transport layer in the OSI model.
TCP (Host to host, flow control).
What can be said about TCP connection?
TCP cares about whether the packets were received; therefore it is a connection-oriented protocol.
When is TCP used over UDP?
TCP is best suited for applications that require high reliability and transmission time is less critical.
How does TCP function?
TCP provides reliable, ordered, and error-checked delivery of a stream of octets between applications running on hosts communicating by an IP network.
What protocols are used in the Transport layer in the TCP/IP model?
TCP, UDP, IGMP, ICMP
Devices and protocols associated with the Transport layer in the OSI model.
TCP/SPX/UDP
What protocols are used in the Application layer in the TCP/IP model?
Telnet, FTP, SMTP, DNS, RIP, SNMP
What does TCP stand for?
Transmission Control Protocol
What can be said about UDP connection?
UDP does not care about whether the packets were received since speed is prioritized; therefore, it is a connectionless protocol.
When is UDP used over TCP?
UDP is suitable for applications that require fast, efficient transmission, such as games and video streaming. UDP's stateless nature is also useful for servers that answer small queries from huge numbers of clients.
What does UDP stand for?
User Datagram Protocol OR Universal Datagram Protocol
packet
a logical grouping of bytes that includes the network layer header and encapsulated data, but specifically does not include any headers and trailers below the network layer.
frame
a term referring to a data link header and trailer, plus the data encapsulated between the header and trailer.
protocol data unit (PDU)
an OSI term to refer generically to a grouping of information by a particular layer of the OSI model. More specifically, an LxPDU would imply the data and headers as defined by Layer x.
Examples of jobs in the Presentation layer in the OSI model.
character code translation, data conversion, data compression, data encryption, character set translation.
Function of the Physical layer in the OSI model.
concerned with the transmission and reception of the unstructured raw bit stream over the physical medium.
Function of Network layer in the OSI model.
controls the operation of the subnet, deciding which physical path the data takes.
TCP streaming of data:
data is read as a byte stream, no distinguishing indications are transmitted to signal message (segment) boundaries.
segment
in TCP, a term used to describe a TCP header and its encapsulated data (also called an L4PDU). Also in TCP, the process of accepting a large chunk of data from the application layer and breaking it into smaller pieces that fit into TCP segments. In Ethernet, a segment is either a single Ethernet cable or a single collision domain (no matter how many cables are used).
Examples of jobs in the Transport layer in the OSI model.
message segmentation, message acknowledgment, message traffic control, session multiplexing, PACKET FILTERING.
de-encapsulation
on a computer that receives data over a network, the process in which the device interprets the lower-layer headers and, when finished with each header, removes the header, revealing the next-higher-layer PDU.
adjacent-layer interaction
on a single computer, one layer provides a service to a higher layer. The software or hardware that implements the higher layer requests that the next lower layer perform the needed function.
UDP streaming of data:
packets are sent individually and are checked for integrity only if they arrive. Packets are definite boundaries which are honored upon receipt, meaning a read operation at the reciever socket will yield an entire message as it was originally sent.
Nickname for the Physical layer in the OSI model.
physical structure (cables, hubs, etc)
Function of Data Link layer in the OSI model.
provides error-free transfer of data frames from one node to another one over the Physical layer.
Examples of jobs in the Network layer in the OSI model.
routing, subnet traffic control, frame fragmentation, logical-physical address mapping, subnet usage accounting,PACKET FILTERING.
Examples of jobs in the Session layer in the OSI model.
session establishment, maintenance and termination, session support, perform security, name recognition, logging, etc.,
Common TCP header size:
source port, destination port, check sum.
Common UDP header size:
source port, destination port, check sum.
Nickname for Session layer in the OSI model.
sync and send to port (logical ports)
encapsulation
the placement of data from a higher-layer protocol behind the header (and in some cases, between a header and trailer) of the next-lower-layer protocol. For example, an IP packet could be encapsulated in an Ethernet header and trailer before being sent over an Ethernet.
same-layer interaction
the two computers use a protocol to communicate with the same layer on another computer.
