(lecture 18)

224.0.0.0/4 represents what kind of address?

Multicast

(lecture 18)

What is multicast?

• IP addresses that stations can subscribe to on a router. 
• When a packet is addressed to a certain multicast address, the router will forward it to its subscribers
• It's a way to create a pseudo broadcast where only a controlled number of stations will hear the traffic

(lecture 18)

What kind of frame is used with multicasts?

Multicast ethernet frame

(lecture 18)

What is a problem with a multicast ethernet frame?

Since only 24 bits of IP address are encoded, 2 addresses can map to the same Ethernet destination address

(lecture 18)

Is IPv6 interoperable with IPv4?

No

(lecture 18)

IPv4 uses a ___ bit address. IPv6 uses a ___ bit address.

32, 128

(lecture 18)

IPv6 consists of ___ groups of ___ bit values

8,16

(lecture 18)

When abbreviating IPv6 address:

Are leading zeroes necessary?

No

(lecture 18)

When abbreviating IP6 addresses:

How do you denote sections with all zeroes?

::

(lecture 18)

What are the 3 advantages of IPv6?

1. Larger address space
2. network security features built in (IPSec)
3. Easier address autoconfiguration (DHCPv6)

(lecture 18)

What are the 3 disadvantages of IPv6?

1. Not interoperable with IPv4
2. Addresses are hard to remember
3. Abbreviation makes it hard to search for in text/log

(lecture 17)

What is the wireless standard?

802.11x

(lecture 17)

What are the 2 wireless network types?

1. AD-HOC
2. Infrastructure

(lecture 17)

What is AD-HOC?

A host connects directly to another host in a point to point fashion

(lecture 17)

What is infrastructure?

• hosts connect to an access point
• access point relays all traffic

(lecture 17)

What kind of topology does a wireless network use?

Bus

(lecture 17)

What are problems with wireless networks?

• There may be collisions when transmitting
• There may be a hidden host

(lecture 17)

What is CSMA/CA?

Carrier sense multiple access with collision avoidance

1. Listen for free channel
2. If free, tell stations within range to be quiet
3. Start transmission to access point
4. Access point ACKs the transmission

(lecture 17)

What are some qualities of WEP?

• Uses an ejncryption key to encode traffic
• Very weak. Can be easily broken

(lecture 17)

What are some qualities of WPA?

• Encryption key changes periodically
• Stronger than WEP
• Password used for additional security

(lecture 17)

What does a Virtual Private Network (VPN) do?

It makes a host on the internet part of your network by encapsulating IP data inside IP data.

(lecture 17)

What are the qualities of VPN protocol Generic Routing encapsulation (GRE)

• IP protocol 47
• Encapsulate an IP packet inside the payload of another IP packet

(lecture 17)

What are the qualities of VPN protocol IPSec?

• Not really a protocol but a protocol suite
• Used to provide authentication and encryption to IP data
• Used in VPN in 2 modes: Transport and Tunneling

(lecture 16)

What are the 4 networking technologies classified according to distance spanned?

1. PAN - spans a region near an individual
2. LAN - spans a building or campus
3. MAN - spans a large metropolitan area
4. WAN - spans multiple cities or countries

(lecture 16)

What are some qualities of dialup?

• uses phone line
• point to point
• uses a modem to send signals as sound
• uses PPP as framing protocol
• 56Kbps maximum speed

(lecture 16)

What are some qualities of Integrated Services Digital Network (ISDN)?

• uses phone line
• 2 main types: Basic Rate Interface (BRI) & Primary Rate Interface(PRI)
• 128 Kbps maximum speed

(lecture 16)

What are some qualities of Digital Subscriber Line (DSL)?

• uses phone line
• ADSL - assymmetric: different up/down speeds
• SDSL - symmetric: same up/down speeds
• Speed mainly depends on distance to central office

(lecture 16)

What are some qualities of Cable?

• Coaxial cable used for TV
• bus topology
• DOCSIS standard
• asymmetric up down speeds

(lecture 16)

What are the qualities of frame relay?

• uses phone line
• similar to ISDN
• T0 = 64Kbps
• T1 = 1.5 Mbps
• T3 = 50 Mbps

(lecture 16)

What are the qualities of synchronous optical networking (Sonet)

• Optical fiber
• Bandwidth can be partitioned to allocate many T1 or T3 into a single optical channel
• OC1 = 50 Mbps
• OC3 = 155 Mbps
• OC12 = 622 Mbps
• OC48 = 2.4 Gbps
• OC192 = 9.6 Gbps

(lecture 15)

What are the two routing protocols?

1. Interior Gateway Protocol (IGP)
2. Exterior Gateway Protocol (EGP)

(lecture 15)

What are the 2 main types of Interior Gateway Protocol?

1. Distance Vector
2. Link State

(lecture 15)

(True or False)

IGP is only used within an Autonomous System

True

(lecture 15)

What is an autonomous system?

A set of machines on a network under the same administrative authority. Autonomous Systems get assigned a number by ARIN

 (lecture 15)

What are the qualities of Distance Vector?

• Regular and periodically shares information with neighbor routers
• Shares the entire routing table
• uses UDP broadcast packets to transmit this data
• determines how many hops it takes to reach a particular network based on infromation it receives from its neighbors
• protocol automatically chooses a path with the lowest hop count

(lecture 15)

What are some qualities of Link State?

• Link state protocols transmit information about the status links on a network
• Unlike distance vector protocols, link state protocols only transmits data once it detects a link has gone down
• more bandwidth efficent than distance vector
• OSPF is the most used protocol (IP proto 89)
• uses a multicast 'hello' protocol to transmit data
• routers get a database dump from the 'king of the network'

(lecture 15)

What are the qualities of Border Gateway Protocol (BGPv4)?

• Routing between autonomous systems
• Neither a distance vector nor link state protocol
• Path vector protocol
• combines metrics such as hop counts, costs and many others to determine paths
• communicates the entire path, not only next hop

(lecture 14)

What range of ports is reserved for 'well known services'?

1-1023

(lecture 14)

What range of ports are the ephemeral ports?

1024-65535

(lecture 14)

What are the 3 main types of Firewall?

1. Layer 2 firewall: switch that forwards frames based on ethernet parameters
2. Layer 3 firewall: router that forwards frames based on IP, TCP, UDP rules
3. Layer 7 firewall: incorporates Layer 2 & 3 firewall but is also capable of analyizing packet contents

(lecture 14)

What are the components of firewall rules?

• Source IP address
• Destination IP address
• IP protocol (ICMP, TCP or UDP)
• Source TCP or UDP port
• Destination TCP or UDP port

(lecture 14)

(True or False)

The order of firewall rules is important

True

(lecture 14)

What does Network Address Translation (NAT) do?

• Translates a private address into an available public address selected from a pool of vailable addresses without any change inports
• Relates 1 private address to 1 public address
• Limits the amount of simutaneous connections from private IP address by the number of available public IP addresses

(lecture 14)

What is Network Address Port Translation?

• A private IP/port is translated into a public IP/port
• one public IP address can be translated to many private IP addresses
• the acting NAT device associates the public/private IP translation based on TCP and UDP ports
• The NAT device tracks TCP/UDP "Flows" in a table and translates accordingly

(lecture 14)

What are the advantages of Network address Translation?

• multiple private address can use a single public address
• technically it is a default blocking firewall since it does not allow incoming traffic to initiate a connection

(lecture 14)

What are the disadvantages of network address translation?

• sometimes connections can be dropped because of timeouts. common in UDP
• unless special measures are taken, public hosts cannot initialte a connection with a private host.