Chapter 1: Networking Models, Ports, Protocols, and Services Flashcards
OSI reference model
Network architecture that enables data to be passed between computer systems
Two common networking models ?
TCP/IP and OSI
Mnemonic for OSI layers ?
All people seem to need data processing
Physical layer
Defines the physical structure of the network and the topology
What makes up the layer 1 hardware ?
Media used on the network, such as type of cable, type of connector, and pinout format for cables
Common topolgies today ?
Mesh, star/hub and spoke, spine and leaf, point-to-point, and hybrid
Which protocols and technologies operate at layer 1 ?
Ethernet, Bluetooth, ISDN, GSM, DSL, T-carrier links, and USB
What other characteristics can the physical layer define ?
The voltage used on a given medium
The frequency at which the signals carrying the data operate
What do these additional characteristics dictate ?
Speed and bandwidth of a given medium
Maximum distance over which a certain media type can be used
Data Link Layer
Node-to-node delivery of data
Frame
Logical grouping of data at layer 2
What else does the MAC sublayer control ?
How devices access a shared transmission medium, such as an Ethernet or fiber optic cable
What is the LLC sublayer responsible for ?
Error and flow-control mechanisms
What protocols and technologies operate at layer 2 ?
High-level data Link control (HDLC)
Layer 2 tunneling protocol (L2TP)
Point-to-point protocol (PPP)
Point-to-point tunneling protocol (PPTP)
Spanning tree protocol (STP)
Virtual LANs (VLANs)
Network Layer
Responsible for routing, providing mechanisms by which data can be passed from one network to another.
How is functionality provided at the Network Layer?
Routing protocols, which are software components
What are protocols responsible for ?
Route selection
Packet
Logical grouping of data at the Network Layer
Two ways for routes to be configured ?
Static or dynamic
Static routes
Manually added to the routing table
Dynamic routes
Use routing protocols such as Routing Information Protocol (RIP) and Open Shortest Path First (OSPF)
Other important protocols at layer 3 ?
IP, ARP Reverse ARP (RARP), Asynchronous Transfer Mode (ATM), IS-IS, IPSec, ICMP, Multiprotocl label switching (MPLS)
Transport layer
Provide mechanisms to transport data between network devices
What are three provided mechanisms from layer 4 ?
Error checking, segmentation, and service addressing
Error checking
Ensure data is correctly sent or received
Service addressing
Ensure data is passed to the right service
Segmentation
Break packets into a manageable size
What is the transport layer also responsible for ?
Data flow control
Data flow control
How the receiving system can receive transmissions
Two common methods of flow control ?
Buffering and winnowing
Buffering
Data is temporarily stored and waits for the destination device to become available
Windowing
Data is sent in a group of segments that require only one acknowledgement
Session layer
Responsible for managing and controlling the synchronization of data between applications on two devices
How does the session layer handle conversations between applications ?
Establishing, coordinates, or terminates them
What are protocols that operate at the session layer ?
NetBIOS, Network file system (NFS), Server message block (SMB)
Presentation layer
Convert data intended for or received from the application layer into another usable format
Common data formats
Graphic files, text and data, sound/video
Graphic files
JPEG, TIFF, GIF
Text and data
Data can be translated into different formats such as the American Standard Code for Information Interchange (ASCII) and Extended Binary Coded Decimal Interchange Code (EBCDIC)
Sound/video
MPEG, MP3, MIDI
Another important function of layer 6 ?
Encryption and decryption
What cryptographic protocol operates at layer 6 ?
Transport layer security (TLS)
Application layer
Provides access to the network for applications
Protocols at layer 7 ?
SSH, BGP, DHCP, DNS, NTP, SMTP, SMB, FTP, HTTP, HTTPS, IMAP, POP3, Real-time transport protocol (RTP), Session initiation protocol (SIP)
Connection oriented
Data delivery is guaranteed, with higher overhead and greater bandwidth demand
Connectionless
Information is just sent with no mechanism to resend data
Internet protocol
Transport data from one node on a network to another
What else does IP perform for network transmissions ?
Fragmentation and reassembly tasks
What other features does TCP add to IP communications?
Flow control, sequencing, error detection and correction
TCP three way handshake
SYN, SYN ACK, ACK
Time-outs
Sending host auto retransmit data if receipt is not acknowledged at a given time period
UDP header fields?
4
Does UDP need to establish a session ?
No
Internet control message protocol (ICMP)
Provide error checking and reporting functionality
ICMP’s most common function ?
Ping utility
Ping
Stream of ICMP each requests to a remote host
Destination unreachable
Destination can’t be contacted
Time exceeded
TTL has exceeded
Traceroute
Uses IP packets TTL time-outs to discover the path a packet takes
ICMP source quench
Tells the sender to slow down. Happens during data influx
Internet protocol security (IPSec)
Designed to provide secure communications between systems
What two protocols make up IPSec ?
Authentication header (AH)
Encapsulating security payload (ESP)
Authentication header (AH)
Provided authentication and integrity checking data packets
Encapsulating security payload (ESP)
Provides encryption services
