OSI Model Flashcards
What does the Application Layer handle?
Provides services directly to user applications. Types of communications. i.e. Email, file transfer, client/server.
What does the presentation layer do?
Performs data transformations to provide a common interface for user applications, including services such as reformatting, data compression and encryption (i.e. ASCII to EBCDIC, BCD to Binary)
What does the Session layer do?
Establishes, manages and ends user connections and manages the interaction between end systems. Services include things like establishing communications as full or half duplex.
What does the Transport Layer do?
Insulates the three upper layers from having to deal with the complexities of layers 1 - 3 by providing the functions necessary to guarantee a reliable network link. This layer also provides error recovery and flow control between the two end points of the network connection.
What does the Network Layer do?
Establishes, maintains and terminates network connections. Routes data to different LAN’s and WAN’s based on network address
What does the Data-Link Layer do?
Ensure the reliability of the physical link established at layer 1. Standards define how data FRAMES are recognized and provide necessary flow control and error handling at frame level
What does the Physical layer do?
Controls transmission of the raw bitstream over the transmission medium. Standards for this layer define parameters as signal voltage swing, duration of voltages (bits) and so on.
Name 6 protocols that operate at the application layer?
BGP, DHCP, DNS, FTP, HTTP, IMAP, IRC, LDAP, MGCP, NNTP, NTP, POP, RIP, RPC, RTP, SIP, SMTP, SNMP, SOCKS, SSH, TELNET, TLS/SSL, XMPP
Name three protocols that operate at Transport layer?
TCP, UDP, DCCP, SCTP, RSVP, ECN
Name 3 protocols that operate at the Internet Layer?
IP (IPv4, IPv6), ICMP, ICMPv6, IGMP, IPsec
Name 3 protocols that operate at the Link Layer?
ARP, InARP, NDP, OSPF, L2TP, PPP, Media Access Control, DSL, ISDN
What is TCP considered?
Reliable Connection
Name the Seven Layers of the OSI Model
Application, Presentation, Session, Transport, Network, Data-Link, Physical
What Layer do Switches operate at?
Layer 2
What Layer do Bridges operate at?
Layer 2
What is the most effective way to troubleshoot?
Layered approach, that is why it is critical to know the OSI model backwards and forwards.
What does HDLC stand for? What layer does it run at?
High Data Link Control - Layer 2
True or False - Does Layer 2 perform error recovery?
False - It does perform Error Detection through Frame check sequencing but does NOT perform error recovery
TRUE or FALSE - Is a MAC address part of the Physical Layer?
False - MAC addresses are layer 2
At the Application, Presentation and Session Layers, Data is called…
DATA
At the Transport layer, Data is placed into …..
SEGMENTS
At the Network layer Data is placed into…
PACKETS
At the Data Link layer, data is placed into….
FRAMES
At the Physical layer, data is….
BITS - Remember, it all comes down to 1’s and 0’s
Which Layers a header?
Application, Presentation, Session, Transport, Network, Data Link - all of them with the exception of the Physical Layer
What Layer adds a Header AND Trailer?
Data Link Layer - The first six layers of the OSI model add a layer specific header.