Exam 3 MIS 4363

how to find the number of bits that we need to borrow to create the needed number of subnets

# of bits needed to create the # subnets required

how to calculate the IP addresses of the subnet, hosts, and direct broadcast

-subnet address = subnet mask in decimal (usually ends in a zero) + incremental value -Range of Host addresses = (subnet address + 1) to (direct broadcast address - 1) -Broadcast Address = Next subnet address using the increment - 1

WAN Topology

1. Ring-based design: "n - 1" circuits needed to lease -Con - More HOPS 2. Star-based design: Pick 1 Hub and connect all computers to it -Pro - At most 2 HOPS, 1 for talking to hub 3. Full-mesh design: all computers connected -Pro - 1 HOP anywhere -Con - High cost, *only do if have a bunch of money 4. Partial-mesh design: most, but not all computers are connected -"partial star with a ring" = Ring + partial star -Very common -Make star based on NW traffic between computers *Ex: DB servers need to have a dedicated circuit so need to use star to connect them

Which of the following is the expected data rate on a 100Base-T network? 10 Mbps 100 Mbps 500 Mpbs 1000 Mbps

100 Mbps

In a 100Base-T network, the distance of cable from a switch to a client computer should not exceed: 25 meters. 50 meters. 100 meters. 200 meters.

100 meters.

The most commonly installed wired Ethernet these day is: 100Base-T or 1000Base-T over Cat 5e. 10Base-t over Cat5. 1000Base-FX over single mode fiber optic cable. 1000Base-t/F over Cat6.

100Base-T or 1000Base-T over Cat 5e.

Types of WAN

3 WAN technologies: Lease a circuit from a common carrier (AT&T, Sprint, Cox, etc.) 1. Dedicated-Circuit service 2. Packet-Switched service More reliable🡪 run over a line in the cloud with only your private traffic 3. Use Internet with virtual private network (VPN) Cheaper, less reliable 🡪 runs over the internet(INTERNET IS NOT WAN) -Anyone can get access to your VPN because public NW traffic

Current WLAN frequencies

802.11ac 2.4 GHz and 5 GHz / 8 Channels 100 Meters / 433 Mbps

What are the two basic components of a backbone network?

A network cable and the hardware devices that connect other networks to the backbone network

directional antenna

A type of antenna that issues wireless signals along a single direction, or path.

Power over Ethernet (PoE)

A wired networking standard that allows electrical power to be sent along with data over standard Ethernet cables

WLAN components

AP connect to clients with radio frequency waves clients each with own NIC

You have been assigned to manage the 802.11ac wireless network shown in figure below. How should the wireless channels be configured on Access Points A, B, and C? All access points should use the same channel. Access points should use different wireless standards. All access points should use different SSIDs. All access points should use different channels.

All access points should use different channels.

Some countries, like China, don't allow users to connect to certain Internet services, such as Facebook. However, if you use a VPN connection to your university/company, you are able to connect to Facebook. Why does this happen? Because the whole packet will be encrypted and they can't read the IP address. Because using VPN, the IP destination address will be your university's IP address rather than Facebook's IP address. Because they don't know what VPN means. Because VPN will not use China's routers and will bypass their infrastructure completely.

Because using VPN, the IP destination address will be your university's IP address rather than Facebook's IP address.

Advantages and disadvantages of having ONLY a core router

Broadcast traffic (ARPs) would be increased but costs would be lower as well as maintenance and management

Your company decided to use dedicated-circuit services for its WAN. What device will be installed at all premises that will be connected in the WAN? CSU/DSU PVC PAD SVC

CSU/DSU

There are two common options when purchasing Internet connection for your home - DSL or Cable. What is the main difference between these two services? Only DSL uses a line splitter. Only Cable requires a modem. Cable is a shared multipoint circuit, while DSL is a point-to-point circuit. You can have more devices on your home network if you use DSL.

Cable is a shared multipoint circuit, while DSL is a point-to-point circuit.

how to know if IP address can be assigned or not.

Can't be assigned if -All 0's in binary Host space = subnet address -All 1's in binary Host space = broadcast address

MAC in WLAN

Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) -DCF and PCF

LAN components

Clients each with own Network interface cards (NICs) NW (Cat5e) cables carrying data Switch/hub -POE port for WAN to transmit electricity and data -ports for clients to transmit data

Which statement about wireless network communication is wrong? Because it uses half-duplex, it is similar to hub-based communication. Clients use CSMA/CS communication. Clients may experience more interference issues than wired Ethernet using Cat 5 cable. Because of the WPA standard, communication is considered as secure as or more secure than wired communication.

Clients use CSMA/CS communication.

Which statement about wireless network communication is wrong? Because it uses half-duplex, it is similar to hub-based communication. Clients use CSMA/CS communication. Clients may experience more interference issues than wired Ethernet using Cat 5 cable. Because of the WPA standard, communication is considered as secure as or more secure than wired communication.

Clients use CSMA/CS communication.

VLAN (Virtual LAN)

Computers are assigned to LAN segments by software rather than hardware Network managers do not need to unplug/replug physical cables to move computers from one segment to another

When would you use a VLAN backbone?

Computers that are in a different geographic locations and it makes it easier to manage broadcast traffic and can better prioritize traffic

cybersecurity implications - Securing WLAN from unauthorized users

Different SSIDs for different user groups (like OU Wi-Fi v. OU Guest Wi-Fi) MAC address filtering Encryption is a MUST

Why do many organizations use a rack for all the network equipment?

Easy maintenance and upgrade Even though can use more cable (not a big deal)

A switched backbone,that uses layer-2 switches, has less broadcast traffic than a VLAN based backbone.

False

What are the advantages of VLANs?

Faster, better at managing traffic flow Prioritize traffic Can put computers in different geographic locations on the same subnet

Physical Topology

How the network is physically installed

logical topology

How the network works conceptually

Your boss asks you to explain why you purchased switches instead of the cheaper hubs - he heard that they do the same thing. What do you tell him to justify the purchase of the switches? Hubs share network capacity with all users so they are slower than switches. You can connect more computers to a switch than to a hub. Hubs do not provide 100 Mpbs connections. Hubs have to be replaced sooner than switches because they fail more frequently.

Hubs share network capacity with all users so they are slower than switches.

Standard Ethernet version

IEEE 802.3 version

Which of the following is not a benefit of a VLAN? Enabling networks to be managed by functional workgroups. Better control over broadcast messages. Improvement of physical layout. Enhanced security.

Improvement of physical layout.

Routed Backbones

In the Core Layer Subnetted Backbones: ***every port on the core router creates its own subnet Distribution Layer Routers - older way of designing Distribution Layer Switches - newer way of designing Good Segmentation of NW's in HW

Layer-2 switches vs Routers

Layer-2 switches operates at the data link layer(MAC addresses) Routers operate at the network layer (TCP/IP)

Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA),

MAC in WiFi :stop and wait still but needs an association with a specific AP so the AP will accept transmission

Which of the following services is not a dedicated-circuit service? T1 MPLS SONET T3

MPLS

MAC address filtering

Method of limiting wireless network access based on the physical, hard-wired address of the wireless NIC of a computing device.

Why are VLANs often not used?

More complex, so only used for large networks

who picks the channel for a WLAN

NIC

WLAN transmission order

NIC > AP AP > WLAN/LAN (sender to AP, receiver to AP)

passive scanning

NIC listens on all channels for a special frame called a beacon frame that is sent out by an AP.

cybersecurity implications - Securing LAN from unauthorized users

Port security / MAC address filtering Physical security: no unauthorized to wiring closets/areas of tech equipment

directory service

Provide information about resources on the LAN that are available to users

Types of Switched BN's

Rack Mounted Switched BN NW architecture-each LAN has own switch connected to a single distribution layer switch Chassis-based Switched BN NW architecture-modules (NW devices) plugged

Main Distribution Facility MDF/CDF/IDF

Room that contains the rack of equipment

Disadvantages of a routed backbone?

Routing takes more time than switching so: slower, more expensive, and require more management

Advantages of a routed backbone?

Segments the network and is managed by a different network manager

Multi-switch VLAN

Several switches are used to operate the VLAN Most commonly used in building backbone networks -- slowly starting to move to core backbone between buildings

network operating system (NOS)

Software that controls the network(one NOS for client and one for server)

When a frame arrives at a switch, what is stored from it along with the port it came in on? Source IP address. Source MAC address. Destination IP address. Destination MAC address.

Source MAC address.

What type of topology do BN uses?

Star topology It connects a series of LANs

Switched Ethernet has a _______________ logical topology and a ________________ physical topology: Bus, star. Bus, bus. Star, bus. Star, star

Star, star

Best Practice Design WAN

Start with more flexible packet switched services Once data needs are clear, move to cheaper dedicated circuit services NOTE: most companies still use VPN over a dedicated circuit so moving data is encrypted Low to Moderate Traffic(>10 Mbps) -packet switched- VPN over internet or frame relay High Traffic(10-50 Mbps) -packet switched-Ethernet, IP, or MPLS -Dedicated- T3 Very High Traffic(50 Mbps - 100 Gbps) -packet switched- Ethernet, IP, or MPLS -Dedicated - SONET

What is the best practice backbone design?

Switched backbone or VLAN distribution layer and routed in core layer

What types of backbones are typically used?

Switched backbones (Distribution layer) that use the same layer-2 switches as LANs

What operates the data-link layer?

Switches

Which of the following WAN services require translation or encapsulation into a new protocol? (check all that apply) T-Carrier SONET Frame Relay Ethernet Services MPLS BNC

T-Carrier SONET Frame Relay

Selecting the best WAN service depends on the data rates you anticipate between different campuses. Suppose, that your data rates will be very high because you need to move large data files across the network. Which of the following services would not meet your needs? T1 Ethernet Services MPLS SONET

T1

ABC Dollar is a growing retail store chain with 500 stores across the US. Most stores are relatively small stores located in small towns. The network will be used for real-time inventory updates and credit card transactions. What WAN would you recommend? (check all that apply) T3 Ethernet Services IP Services VPN over DSL

T3 Ethernet Services IP Services

Topology

The basic geometric layout of the network - the way in which the computers on the network are interconnected

Collision Detection (CD)

The capability of a layer 2 network protocol to know when two network nodes send data simultaneously, creating unreadable data.

What is each backbone connected to?

The router which is connected to a core router

Domain Controllers

The servers that contain the Active Directory databases. (like a DNS server)

Patch Cables

The very small cables used to connect devices in the rack

What do OC-1 and T3 have in common? They both run over twisted pair cables. They offer about the same data rate (44.376 Mbps and 51.84 Mbps). They both run over fiber optic cables. Nothing, the are completely different services.

They offer about the same data rate (44.376 Mbps and 51.84 Mbps).

what is not true about the traditional network design process? It follows a very structured systems analysis and design process. A precise estimate of the amount of data that each user will send and receive is developed. This process is cheap and fast. The suggested circuits must support the estimated traffic plus a modest increase in traffic.

This process is cheap and fast.

When would you use a routed backbone?

To connect different buildings on the same enterprise campus backbone network

Each computer must be physically connected by network circuits to the other computers in the network.

True

VLAN switches are a special combination of layer-2 switches and routers.

True

VLANs are networks in which computers are assigned to LAN segments by software rather than by hardware.

True

a Request for Proposal (RFP) specifies what equipment, software, and services are desired and asks vendors to provide their best prices.

True

the key concept in the building-block process is that using a few standard components throughout the network is cheaper in the long run than to use a variety of different components to build different parts of the network.

True

What do backbone network (BN) switches do?

Use the mac address to forward packets between network segments They learn addresses by reading the source and destination addresses

Chassis Switch

Used instead of a rack Enables users to plug modules directly into the switch They are used because they are flexible and easier to upgrade the switch

Routed Backbone (Subnetted backbones)

Used routers to connect to different LANs/subnets

When are routed backbones often used?

Used to connect different buildings on the same enterprise campus backbone network

Layer-2 switch

Uses MAC addresses from the NICs to decide where to forward frames Hardware-based

Single-switch VLAN

VLAN operates only inside one switch Software is used to assign computers attached to the switch to different VLAN segments

VLANs vs Routers

VLANs create multiple subnets inside the switch Routers create subnets between switches

McWansey & Company is a consulting firm with offices in five cities across upstate New York. A typical office has 5-7 employees. The network will typically be used to exchange Word and PPT files. What WAN would you recommend? T3 VPN over DSL Ethernet Services IP Services

VPN over DSL

what are the three components of the network architecture that make up the enterprise edge?

WAN, internet access, e-commerce edge

Security for wireless ethernet

WEP, WPA, 802.11i, MAC address filtering, *wardriving

When would you use a switched backbone?

When network admins want to spread the traffic around the network more efficiently and where network capacity is not tied to physical location

Best Practice LAN design

Wired Ethernet (LAN) -100 Base T or 1000 Base T over Cat5e -Cable Plan: follow logical and physical design Wireless Ethernet (WLAN) -802.11 ac -Switch (all access points connected to) supports POE (so can have electricity) -Site Survey: must do to know where to put AP *^usually not all same size NW traffic (people, furniture, etc. absorbing the signal) *^need to know if the radio frequencies from access point will reach the client computers -Traffic travels in 3D - horizontally and vertically *^Can go across multiple floors in a building so need to know the access points won't cause a collision

Suppose you bring your laptop into a room with a 802.11ac wireless access point running at 300 Mbps that is connected into a 100Base-T switch which leads to the backbone. Your friend has connected her laptop via a Cat 5 cable to the switch. If you are the only computer using the AP: Your throughput will be about the same as hers. Your throughput will be faster than hers. Your throughput will be slower than hers. We don't know because we don't have sufficient information to make a decision.

Your throughput will be about the same as hers.

Suppose you bring your laptop into a room with a 802.11ac wireless access point running at 300 Mbps that is connected into a 100Base-T switch which leads to the backbone. Your friend has connected her laptop via a Cat 5 cable to the switch. If there are 20 computers using the AP: Your throughput will be faster than hers. Your throughput will be about the same as hers. Your throughput will be slower than hers. We don't know because we don't have sufficient informaiton to make a decision.

Your throughput will be slower than hers.

active scanning

a NIC transmits a special frame called probe frame on all active channels on its frequency range.

the main output of the needs analysis is:

a logical network design

wardriving

a malicious activity driving through a neighborhood with a wireless-enabled notebook computer goal of locating homes and businesses that have wireless networks in order to gain access to them

Thelogical and physical topologies ofWi-Fi are the same as those of hub-based Ethernet:

a physical star and a logical bus.

what are the three layers, also the first three components, of the network architecture?

access, distribution, and core layers

what is the proper placement of the organization's servers (eg., database servers, email servers)

all servers should be in the organization's data center

omnidirectional antennas

antenna transmits in all directions simultaneously

why is designing circuits for WAN more difficult than for LAN?

because LAN circuits come in standard sizes (e.g., 100 Mbps or 1 Gpbs). This is not true for WAN circuits that offer many more choices in standard sizes and it is much more difficult to estimate circuit loading for many users than it is for one user.

cut-through switching

begins the forwarding process before it has received the entire frame

another term that describes the core layer is:

campus backbone

star

centralAP towhich all computers direct their transmissions

lightweight directory access protocol (LDAP)

client computer sends a message to the ADS domain controller with this when it wants to access available resources

Components in a LAN

clients, servers, NICs, network circuits, hubs, switches, access points, and network operating system

AP's enable

computers close to each other to communicate

Network hubs and switches

connect network cables (like with a plug) act as repeaters(bc attenuation)

Carrier Sense Multiple Access with Collision Detection (CSMA/CD)

contention-based media access control technique used by ethernet "wait until the circuit is free and then transmit"

3 modes of Switch Operations

cut through switching store and forward switching fragment free switching

how to find the increment

decimal value of the last possible "1" bit in binary

Improving LAN Performance Demand

decrease demand i. Understand NW traffic *Application Layer protocols 🡪 need to know what kind of packets are traveling on the NW and if they are moving large amounts of data across the NW ii. Shift demand from WLAN to LAN *Because LAN is star and WLAN is bus technology iii. Limit use of Applications *Ex: OU Wi-Fi doesn't allow TOR to be used

Improving LAN Performance Devices

enhance performance i. Upgrade AP ii. Wireless LAN Controller (WLC): device plugged into distribution layer switch that manages access points *All logic for the access points comes from this *Help with AP functionality iii. Upgrade servers

Hub-based Ethernet

ethernets logical topology when hubs are used all computers connected to one half duplex circuit running the length of the network

1000base-F Ethernet standard

fiber optic cables or ethernet but mostly fiber optic 1, 10, 40, 100 GbE

NOS Server Software enables

file server, print server, or database server to operate. replaces existing OS acts as the application software by executing the requests sent to it by the clients

fragment-free switching

frames retransmitted once the header (first 64 bytes) is received and has no errors Compromise between store and forward and cut-through

What technologies are part of the access layer (LAN).

hub, switch, and access point *not a router

Improving LAN Performance Circuits

increase circuit capacity i. Upgrade circuits to 1 Gbps ii. Upgrade/add Aps iii. NW segmentation - More subnets with different SSID's *Ex: OU Wi-Fi - has own subnet with own SSID and security restrictions (user authentication and MAC address filtering) vs. OU Guest - own subnet and SSID No restrictions iv. Add new Switches - so can add more AP's and then more users on NW

Wi-Fi Protected Access (WPA)

key is changed for every frame that is transmitted to the client

Bus Topology

lone half duplex circuit running the length of the network

802.11i (WPA2)

master key client and AP negotiate a new key Uses AES (Advanced Encryption Standard)

Point Coordination Function (PCF)

media access control (MAC) technique used in IEEE 802.11 based WLANs, including Wi-Fi relies on an access point to coordinate the communication within the network process -request to send(RTS) -clear to send(CTS)

user profile in a Network profile

needed for each person who uses the LAN

NOS Client Software

performs the functions associated with the data link and the network layers and must interact with the application software and the computer's own operating system.

NOS Server Software

performs the functions associated with the data link, network, and application layers and usually the computer's own operating system.

Connect point where a cable can be plugged in

port(all have unique numbers)

Access Point(AP)

radio transceiver that plays the same role as a hub or switch in wired Ethernet LANs.

store and forward switching

receives the entire frame before forwarding

Distributed Coordination Function (DCF)

relies on the ability of computers to physically listen before they transmit Process: -Listen -no one transmitting? then transmit -listen while transmitting -if collision stop transmitting and issue a jamming signal -wait random amount of time and start at 1

10base-T Ethernet standard

revolutionized ethernet and made it most popular LAN in world *100Base - T and 1000Base -T most common today

scanning

searching for an available AP

Switched Backbones

segmenting in HW Most common type of BN in distribution layer Topology - STAR In the Distribution and Access Layer All LAN switches are Dual homed so uses Spanning Tree Protocol(STP) to fix redundancy

collision domain

shared multipoint circuit in a hub that computers take turns using

collision

simultaneous transmission of frames that collide and destroy each other

SOHO

small office/home office

network profile

specifies what resources on each server are available on the network for use by other computers and which devices or people are allowed what access to the network

Forwarding Table

table lists the ethernet address of the computer connected to each port on the switch

bus

the radio frequencies are shared

AP's don't interfere with each other because

transmitted at different frequencies using a channel

servers should never be placed on a WLAN

true

WLAN frame layout with IEEE 802.11x

types of wireless ethernet

Most wired LANs built with

unshielded twisted-pair (UTP) cable, shielded twisted-pair (STP) cable, or fiber-optic cable.

Wireless LANs(WLAN)

use radio transmissions to send data between NICI and Access Point(AP)

Wireless Equivalent Privacy (WEP)

user ID and password required The oldest and weakest form of wireless encryption.

A LAN provides network access to

users, data center, and e commerce edge

Frames

what flow into the bus and then to all computers on the LAN

Network Interface Card (NIC)

wired network - physically connects computer to network wireless networks - radio transmitter that sends and receives messages on a specific radio frequency

Active Directory Service (ADS)

works in much the same manner as TCP/IP's DNS service