Exam 200-301 topic 1 question 697 discussion

control plane, create routing table

My disdain for Cisco grows...

In an SDN architecture, the function that is centralized on the controller is: A. Creates the IP routing table This is correct because: In SDN, the control plane is separated from the data plane and centralized in the SDN controller. The control plane is responsible for making decisions about where traffic should be sent, which includes creating and maintaining routing tables. The SDN controller acts as the "brain" of the network, maintaining a global view of the network topology and making centralized decisions about routing and forwarding. One of the key functions of the SDN controller is to calculate and distribute routing information to the network devices (switches and routers) in the data plane. This includes creating and updating IP routing tables. By centralizing this function, SDN allows for more efficient and dynamic routing decisions based on real-time network conditions and policies.

Im going with C as well

A is also a function of the controller. However, 'centralized on a controller' is C...?

C FTW!

C is Correct

Im going with C In traditional networking, routing decisions are typically made by individual network nodes (routers) based on locally stored routing tables. However, in SDN, the control plane functionality, including routing decisions, is centralized on a controller. The controller determines the routing paths and policies for network traffic flow based on global network conditions and policies, then communicates these decisions to the data plane devices for forwarding. Why not A? While in traditional networking, individual network nodes (routers) create and maintain their own IP routing tables based on routing protocols and configurations, in an SDN architecture, this function is centralized on a controller. The controller, rather than individual nodes, determines the routing paths and policies for network traffic flow. Therefore, the correct answer is not A, but C.

760 What is the function of the controller in a software-defined network? A. forwarding packets B. multicast replication at the hardware level C. making routing decisions D. fragmenting and reassembling packets Answer C best choice

A is correct Controller is in Control Plane, Data Plane is one who makes routing decisions.

Making a routing decision = looking up destination route, which is an action done for a message....this a data plane process However creating routing table is a control plane process, hence A

Official Cert Guide Vol 2 Page 360 "The term control plane refers to any action that controls the data plane. Most of these actions have to do with creating the tables used by the data plane, tables like the IP routing table, an IP Address Resolution Protocol (ARP) table, a switch MAC address table, and so on. By adding to, removing, and changing entries to the tables used by the data plane, the control plane processes control what the data plane does. You already know about many control plane protocols—for instance, all the IP routing protocols."

Routing Decision = Routing Matching table , so its not correct , i think A the better one

It´s A - control plane

A SDN consists of control, data, and management planes. The control plane performs forwarding decisions and other functions, like quality of service (QoS). In contrast, the data plane is the network that switches or forwards devices handling the data packets and taking inputs from the control plane. https://www.splunk.com/en_us/blog/learn/control-plane-vs-data-plane.html#:~:text=It%20is%20responsible%20for%20routing,path%20for%20forwarding%20network%20traffic.

C. Makes a routing decision In an SDN (Software-Defined Networking) architecture, the function of making routing decisions is centralized on a controller. In SDN, the control plane, which involves tasks such as making routing decisions and managing network traffic, is separated from the data plane. The SDN controller is responsible for making decisions about how data should be forwarded through the network. This centralized control allows for more dynamic and programmable network management.

I think I unraveled the conundrum: the key is the difference between "forwarding" and "routing", by definition data plane is forwarding not routing, routing decision is not "forwarding". What data plane does is a lookup of the destination routes to find a match before the packet is forwarded. This is not a routing decision, therefore correct answer is C, because this is a function of the control plane.