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 ______.
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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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