Podcast
Questions and Answers
Each router contains a forwarding table also known as a ______
Each router contains a forwarding table also known as a ______
flow table
In generalized forwarding, the action taken can include drop, copy, modify, or ______ the packet.
In generalized forwarding, the action taken can include drop, copy, modify, or ______ the packet.
log
The concept of 'match plus action' is a fundamental principle of ______
The concept of 'match plus action' is a fundamental principle of ______
SDN
Middleboxes are often used to manage tasks such as ______ traffic or ensuring security.
Middleboxes are often used to manage tasks such as ______ traffic or ensuring security.
In OpenFlow, routers typically match on the longest destination IP ______.
In OpenFlow, routers typically match on the longest destination IP ______.
Generalized forwarding allows for matching over many header ______, including link, network, and transport layers.
Generalized forwarding allows for matching over many header ______, including link, network, and transport layers.
For a switch, the matching criterion is the destination ______ address.
For a switch, the matching criterion is the destination ______ address.
Flow table entries in OpenFlow consist of matching patterns and corresponding ______.
Flow table entries in OpenFlow consist of matching patterns and corresponding ______.
The term 'network programmability' refers to the ability to ______ behaviors across the network.
The term 'network programmability' refers to the ability to ______ behaviors across the network.
NAT stands for ______ Address Translation, which helps in maintaining unique IP addresses.
NAT stands for ______ Address Translation, which helps in maintaining unique IP addresses.
Initially, middleboxes referred to proprietary (closed) hardware solutions, moving towards 'whitebox' hardware implementing open ______.
Initially, middleboxes referred to proprietary (closed) hardware solutions, moving towards 'whitebox' hardware implementing open ______.
SDN features logically centralized control and configuration management often in public or private ______.
SDN features logically centralized control and configuration management often in public or private ______.
Network Function Virtualization (NFV) offers programmable services over whitebox networking, computation, and ______.
Network Function Virtualization (NFV) offers programmable services over whitebox networking, computation, and ______.
RFC 1958 states that the architecture of the Internet is seen as simple ______.
RFC 1958 states that the architecture of the Internet is seen as simple ______.
The Internet Protocol serves as the narrow ______ in the architectural principle of the Internet.
The Internet Protocol serves as the narrow ______ in the architectural principle of the Internet.
According to the end-to-end argument, functionality can be correctly implemented only with the knowledge of the application standing at the ______ points.
According to the end-to-end argument, functionality can be correctly implemented only with the knowledge of the application standing at the ______ points.
The end-to-end argument suggests that implementing certain functions in the network can only be an ______.
The end-to-end argument suggests that implementing certain functions in the network can only be an ______.
Some network functionality, such as reliable data transfer, may be implemented in the network or at the network ______.
Some network functionality, such as reliable data transfer, may be implemented in the network or at the network ______.
The last question regarding forwarding tables in destination-based forwarding pertains to how they are ______.
The last question regarding forwarding tables in destination-based forwarding pertains to how they are ______.
The intelligence and complexity in the Internet architecture is believed to reside at the network ______.
The intelligence and complexity in the Internet architecture is believed to reside at the network ______.
Study Notes
Generalized Forwarding, SDN
- Each router uses a forwarding table (also called flow table) to manage network traffic.
- The "match plus action" abstraction is used where specific patterns are matched within arriving packets and corresponding actions are taken.
- Generalized forwarding: many header fields can determine the action to be taken. Many actions are possible: drop, copy, modify, or log the packet.
- A flow is defined based on packet header field values (in the link, network, and transport layers).
- When a packet is received, it’s matched to the entries in the flow table based on specific header field values.
- Actions: if a packet matches an entry, it can be dropped, forwarded, modified, or rerouted to a controller.
- Priority levels can be set on rules to avoid conflicts if multiple rules match a packet.
- Counters keep track of the number of packets and bytes that match each entry.
- OpenFlow is used to create flow tables that can be used to control network traffic.
OpenFlow
- OpenFlow is a protocol that uses match + action rules to control how packets are handled.
- OpenFlow defines a standard interface for communication between network devices and a centralized controller.
- OpenFlow enables a centralized controller to configure and manage flow tables on individual devices.
- OpenFlow permits a single, centralized controller to manage the behavior of a network.
- OpenFlow allows dynamic network management, giving network operators more control over traffic flow and network behavior.
Middleboxes
- Middleboxes are network devices that perform functions like security filtering, network address translation (NAT), and quality of service (QoS).
- They are often deployed between the network edge devices (firewalls, routers, and switches) and end users.
- Middleboxes can be implemented through SDN and NFV.
- Traditional middleboxes were often proprietary hardware solutions, but now there is a transition to whitebox hardware.
- SDN (Software-Defined Networking) provides a centralized control point for configuring and managing the network.
- NFV (Network Function Virtualization) uses software to perform network functions on generic hardware platforms instead of relying on specific hardware.
- Middlebox functionality is often defined through flow-based mechanisms and programmed directly through APIs.
The IP Hourglass
- The IP hourglass is a model that describes the architecture of the Internet, with the IP layer at the narrow waist.
- This model highlights the simplicity of the IP layer and the complexity of the network edges, advocating for application intelligence over network intelligence.
End-to-End Argument
- The end-to-end argument emphasizes that many network functions should be implemented at the edges of the network, rather than within the network itself.
- If a function can only be correctly implemented end-to-end, then implementing it in the network can, at best, be only an optimization.
- Many network functionalities (e.g., reliable data transfer, congestion control) can be implemented in the network or at the network edge.
- This argument questions the need for complex in-network functionality and emphasizes application-layer control.
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Description
This quiz covers the concepts of generalized forwarding and how it operates within Software Defined Networking (SDN). Explore key aspects such as flow tables, the match plus action model, and the various actions that can be taken based on packet header fields. Test your understanding of these fundamental networking principles.
