Kevin Jin Networks Quiz 4

Per-router control plane

Individual routing algorithm components - with a component operating in each and every router - interact with each other in the control plane. The individual routing algorithm component executing in a given router computes the local forwarding table for the router

Which of the functions below belong in the controller layer labeled "Communication to/from controlled device"?

OpenFlow protocol

Routing

Refers to determining the route taken by packets from source to destination, and is implemented in the control plane

Static Routing

Routes change slowly over time.

good path

Routing algorithms typically work with abstract link weights that could represent any of, or combinations of, all of, or combination of, all of the other answers

Interdomain Routing

Routing among different ASes ("networks").

Intradomain Routing

Routing among routers within same AS ("network")

Dynamic Routing

Routing changes quickly over time.

Consider the SDN layering shown below. Match each layer name below with a layer label

(a) Network-control applications (c) SDN-controlled switches

Among the following protocols, terminology or considerations, indicate those that are associated with "routing within a single network (typically owned and operated by one organization)." intra-domain routing -Driven more by routing policy than end-end routing -performance -inter-domain routing -inter-AS routing -BGP -intra-AS routing -OSPF -Driven more by performance than by routing policy

- OSPF - Intra-AS routing - Intra-domain routing - Driven more by performance than by routing policy

Which of the functions below belong in the controller layer labeled "Network-wide distributed, robust state management"?

-Flow tables -Link-state information -Statistics -Host information -Switch information

OSPF (Open Shortest Path First) Protocol

-Implements hierarchical routing -Uses a Dijkstra-like algorithm to implement least cost path routing. -Is an intra-domain routing protocol -Floods link state control information -Finds a least cost path from source to destination

Which of the functions below belong in the controller layer labeled "Interface, abstractions for network control apps"?

-Network Graph -Intent

Consider Dijkstra's link-state routing algorithm that is computing a least-cost path from node a to other nodes b, c, d, e, f. Which of the following statements is true. (Refer to Section 5.2 in the text for notation.)

-Suppose nodes b, c, and d are in the set N'. These nodes will remain in N' for the rest of the algorithm, since the least-cost paths from a to b, c, and d are known. -The values computed in the vector D(v), the currently known least cost of a path from a to any node v, will never increase following an iteration. -In the initialization step, the initial cost from a to each of these destinations is initialized to either the cost of a link directly connecting a to a direct neighbor, or infinity otherwise.

ICMP (Internet Control Message Protocol)

-The The TTL-expired message type in ICMP is used by the traceroute program -ICMP messages are carried directly in IP datagrams rather than as payload in UDP or TCP segments. -ICMP is used by hosts and routers to communicate network-level information

Software Defined Networking (SDN)

A (typically) remote controller gathers information from routers, and then computes and installs the forwarding tables in routers.

Centralized, Global Routing

All routers have complete topology, and link cost information.

Decentralized Routing

An iterative process of computation, exchange of information with neighbors. Routers may initially only know link costs to directly-attached neighbors.

Forwarding

refers to moving packets from a routers input to appropriate router output, and is implemented in the data plane