MOD 4 - Network Layer - Data Plane Flashcards
What is IP fragmentation and why is it needed?
Fragmentation = when a datagram has to be broken up into smaller datagrams to fit the frame size of a certain network
Is the Internet a datagram or virtual circuit network? Explain what that means in terms of the services the Internet’s network layer provides to the transport layer
The Internet is a datagram NETWORK. This means that the network layer only provides a datagram service, in the case of the internet, best-effort. The network layer doesn’t provide reliability or connection services to the transport layer.
Give an example of IP’s in classes A,B,C and D.
Class A: 10.0.0.5
- start with 0-127, 0 bin
- 1 byte in network address
- for governments
Class B: 128.114.48.62
- start with 128-191, 10 bin
- 2 bytes in network address
-for large companies
Class C:
- start with 192-223, 110 bin
- 3 bytes in network address
-for small companies
Class D:
- start with 224-239 1110 bin
- 28 bits in network address
of host that can be connected = 2^host bits
An IP address is split into which 2 addresses?
Network address & Host address
Devices within the same network share the same network address but have different host addresses
What is DHCP?
DHCP = dynamic host configuration protocol
- allows host to dynamically obtain its IP address from network server when it joins a network
- “plug and play” / gives you an IP dynamically and lets you join the network
- if DHCP is not available, you need to configure your IP manually (ISP provides you IP)
What is SDN and what are its main components?
SDN’s basic idea is to separate the data and control planes.
- Network switches become simple forwarding devices
- the control logic is implemented in a logically centralized controller (or network operating system)
Main components:
- Forwarding Devices (Data plane) : perform a set of elementary operations
- Control Plane : “network brain”, program forwarding tables
- Southbound Interface : Defines the instruction set of the forwarding devices. (OpenFlow)
- Northbound Interface : An API to application developers
- SDN application: programs that explicitly, directly, and programmatically communicate
their network requirements and desired network behavior to the SDN Controller
SUMMARY: SDN separates the control plane from the data plane, allowing centralized control over network devices.
How does routing differ in SDN compared to traditional networks?
- SDN uses software and application programming
- traditional networks use physical routers and switches to route packets.
physical devices -> forwarding parts
What is ARP? what is MAC?
Address Resolution Protocol (ARP) is a protocol used to map an IP address to the corresponding MAC address in a local network.
MAC (Media Access Control) address is a unique identifier assigned to a network interface controller for communications at the data link layer of a network, commonly represented as a 48-bit hexadecimal number.
What is OpenFlow and what is it used for? What is OpenDaylight?
OpenFlow = protocol for communicating with controller.
OpenFlow allows a central controller to communicate and controls the behavior of network devices, such as switches and router
OpenDaylight = framework for implementing SDN applications
What is a subnet?
isolated network, sub-division of the bigger network (makes the network more manageable)
devices interfaced with the same subnet part of IP address can physically reach each other
routers manage comms between subnets
organizations manage their size
Define Generalized Forwarding and Destination Forwarding. Highlight the differences in their functionalities.
▪ destination-based forwarding: forward based only on destination IP address (traditional)
▪ generalized forwarding: forward based on any set of header field values (not strictly based on destination.)
Compare host Names, Application Port Numbers, IP Addresses, and MAC Addresses in terms of their usage in networking.
Host Names: Human-readable names for devices.
Application Port Numbers: Identify specific applications or services.
IP Addresses: Network layer addresses for routing.
MAC Addresses: Data link layer addresses for local network communication.
SDN advantages?
-Network switches become simple forwarding devices and
-the control logic is implemented in a logically centralized controller (or network operating system),
-Simpler management
-Less dependence on vendors and standards
-Easier interoperability
Compatibility only in “wire” protocols
-Simpler, cheaper equipment
Minimal software
-Provides the ability to accelerate service deployments.
What are IP destination and source addresses of a DHCP discover message?
What are IP destination and source addresses of a DHCP offer message? What are the values that are contained in a DHCP server offer message?
DISCOVER MESSAGE
destination: 255.255.255.255
Indicates that the DHCP Discover message is intended for all devices on the local network segment, allowing DHCP servers to respond to the client’s request.
source: 0.0.0.0
This is because the client has not yet been assigned an IP address; it’s essentially requesting one.
OFFER MESSAGE
destination: 255.255.255.255
DHCP broadcasts an offer using
IP255.255.255
source: real DHCP server IP address
VALUES CONTAINED
- IP for client
- gateway address
- IP for lease time
In OpenFlow, how to you set the priority order of rules given IP’s. (ex: 12.1.2.0/24 forwards out link 1,12.0.0.0/8 forwards out link 2, 12.1.0.0/16 forwards out link 3.)
The highest priority should go to the longest prefixes (/#).
