Telecommunications and Network Security Flashcards
What is a LAN?
A local area network (LAN) is a data network that operates across a relatively
small geographic area. LAN connects
workstations, servers, printers, and other devices so that network resources, can be shared
What is a WAN?
A Wide Area Network connects multiple LANs and other WANs by using telecommunications devices and facilities.
Types of WANs (3)
Internet, Intranet and Extranet
OSI Reference Model (7 Layers)
(1) Physical, (2) Data Link, (3) Network, (4) Transport, (5) Session, (6) Presentation, (7) Application.
Please Do Not Tells Sales People Anything
OSI Model memory mnemonic
VLAN
Virtual LAN. Implemented on network switches as a way lf logically grouping users and resources together.
Star Topology
Layer 1. Each node is directly connected to a switch, hub or concentrator.
Mesh Topology
All systems are interconnected to provide multiple paths to all other resources.
Ring Topology
A closed loop that conects end devices in a continuous ring.
Bus Topology
Bus
In a bus (or linear bus) topology, all devices are connected to a single cable
(the backbone) that’s terminated on both ends.
What is a Repeater?
Layer 1 device. Amplifies a signal to compensate for attenuation
What is a Hub?
aka a “Concentrator”, is used to connect mulitple LAN devices together. Dumb device. Sends signals to ALL devices on network.
What is a switch?
Layer 1/2. Used to connect multiple LAN device. A smart device. Sends signals to destination address only. The smart part is layer 2. The physical device is layer 1.
Data Link Layer (Layer 2)
Ensures message are delivered to proper device. The Data Link Layer formats messages from layers above
into frames for transmission, handles point-to-point synchronization and error
control, and can perform link encryption
Data Link Layer - Sublayers
LLC & MAC.
Layer 2 Protocols and transmission methods?
ARCnet, Ethernet, Token-ring, FDDI, ARP, RARP
FDDI
Fiber Distribution Data Interface: The FDDI protocol transports
data to the physical LAN medium by using the token-passing media access
method that we discuss in the preceding section. It’s implemented as a dual
counter-rotating ring over fiber-optic cabling
ARP
Address Resolution Protocol: ARP maps Network Layer IP
addresses to MAC addresses. ARP discovers physical addresses of
attached devices by broadcasting ARP query messages on the network
segment. IP-address-to-MAC-address translations are then maintained in
a dynamic table that’s cached on the system. Layer 2 protocol
RARP
Reverse ARP. RARP maps MAC
addresses to IP addresses. Layer 2 protocol
Unicast
Packets sent from single destination to a single destination.
Multicast
Packets are copied and sent from source to multiple destinations using special multicast IP address
Broadcast
Packets are copied and sent from source to every device on destination network using broadcast IP address.
IEEE 801.11a (WLAN)
54 Mbps - 5 GHz
IEEE 801.11b (WLAN)
11 Mbps; 2.4 GHz
IEEE 801.11g (WLAN)
54 Mbps, 2.4 GHz (compatible with 802.11b)
IEEE 801.11n (WLAN)
5 GHz or 2.4 GHz
L2F
WAN Layer 2 Forwarding Protocol. A tunneling (encapsulation) protocol by Cisco. Used to implement VPNs and specifically PPP. Does not encrypt
L2TP
WAN Layer 2 Tunneling Protocol. Used for VPSs. Uses UDP port 1701 to create tunneling session. May be used w/encryption protocol (e.g. IPSec).
PPP
Point-to-Point Protocol. Succeeded SLIP. Provided router-to-router and host to network connections.
PPTP
Point-to-point Tunneling Protocol. A Microsoft tunneling protocol used for VPNs and specifically PPP. Does not provide encryption, relies on other protocols.
SLIP
Serial Line IP.
