Distance vector routing Flashcards
What is Distance Vector (DV) Routing?
A routing method where routers share distance information (typically hop count) with neighbors to determine the best path to destinations. It’s also known as Bellman-Ford forwarding.
What are the key elements in a DV routing table?
Destination network address
Distance (in hops) to the destination
Port used to reach the destination
How are DV routing tables built and maintained?
Initialization: Routers add directly connected networks with distance 0.
Periodic Updates: Routers broadcast their tables to neighbors, incrementing hop counts.
Dynamic Adjustments: Tables update when shorter paths are discovered.
What is the role of Routing Information Protocol (RIP) in DV routing?
RIP collects and advertises routing information, maintains routing tables, and broadcasts distance vectors every 30 seconds. It limits hop counts to 15, with 16 representing unreachable destinations.
What is the “Count to Infinity” problem in DV routing?
A situation where routers create looping routes, causing hop counts to increment indefinitely until a route is declared unreachable.
What is the Hold Down mechanism in DV routing?
A technique where routers delay advertising disconnected routes for a specific time (e.g., 180 seconds in RIP) to ensure consistency.
What is Poison Reverse in DV routing?
A method where disconnected routes are immediately advertised with a cost of infinity, prompting neighbors to find alternative paths or mark the destination as unreachable.
What is the maximum hop count in RIP, and why?
The maximum hop count is 16, with 15 being the network limit. This prevents infinite routing loops and limits network size.
How do routers conceptualize the path to a destination in DV routing?
Distance: The hop count
Direction: The port to forward packets
Destination: The network address
Shorter paths are always preferred, avoiding redundant or inefficient routes.
What is the “Count to Infinity” problem in DV routing?
By preventing routers from advertising a route back to the neighbor from which it was learned, reducing the chance of loops.
