Network B - AI Flashcards
(40 cards)
What are Wide Area Networks (WANs)?
Large networks that may span the globe
WANs have generalized topologies and require sophisticated techniques.
What do routing tables specify?
Next node in a route to a specified destination and the cost to get there
They do not normally specify the entire route.
What is a graph abstraction in networking?
A representation of nodes and edges, where N is the set of nodes/routers and E is the set of links/edges
Example: N = {u, v, w, x, y, z}; E = {(u,v), (u,x), (v,x), (v,w), (x,w), (x,y), (w,y), (w,z), (y,z)}.
What does cost in a graph represent?
Cost could be inversely related to bandwidth or congestion
Example: c(w,z) = 5.
What is the key question for routing algorithms?
What is the least-cost path between two nodes?
This determines the efficiency of data transmission.
How are routing algorithms classified based on information?
Global or decentralized information
Global: all routers have complete topology; Decentralized: routers know only their neighbors.
What is the difference between static and dynamic routing?
Static: routes change slowly; Dynamic: routes change more quickly in response to link cost changes.
What is centralized routing?
All interconnection information is generated and maintained at a single central station
The central station broadcasts routing information to all nodes.
What is distributed routing?
No central control; each node must determine and maintain routing information independently
More complex than centralized due to limited knowledge of the entire network.
What is the Bellman-Ford Algorithm used for?
It finds shortest paths from a source node to all other nodes in a graph
Initialization sets distance to itself as 0 and others as infinity.
What are the steps in the Bellman-Ford Algorithm?
- Initialization
- Relaxation
- Termination
The algorithm typically runs for V - 1 iterations, where V is the number of nodes.
What does static routing imply?
Once the node determines the routing table, it does not change
The initial cheapest path may not be the cheapest path later.
What is adaptive routing?
Allows the network to respond to changes and update its routing tables accordingly
It can lead to implementation challenges.
What is Dijkstra’s algorithm often referred to as?
The Shortest-path Algorithm or Forward Search Algorithm
It is a centralized, static algorithm that can be made adaptive.
What does hierarchical routing help manage?
Scalability and administrative autonomy
It allows networks to control routing while connecting to other networks.
What are autonomous systems (AS) in networking?
Routers typically under the same administrative control that run the same routing protocol
AS are involved in intra-AS and inter-AS routing.
What does the inter-AS routing algorithm do?
Determines how to forward packets to destinations outside of its own AS
It involves learning which destinations are reachable through other AS.
What is the purpose of a forwarding table?
To direct packets to their correct destinations based on routing information.
What types of routing algorithms configure the forwarding table?
Intra-AS and inter-AS routing algorithms.
What does intra-AS routing set entries for?
Internal destinations.
What does inter-AS routing set entries for?
External destinations.
What must AS1 learn when a router receives a datagram destined outside of AS1?
Which destinations are reachable through AS2 and AS3.
What is the main job of inter-AS routing?
To propagate reachability information to all routers in AS1.
In the example of setting a forwarding table, what does router 1d learn from inter-AS protocol?
Subnet x is reachable via AS3 but not via AS2.
