RSE Chapter 3 – Routing Dynamically

What is the main purpose of dynamic routing protocols?

To discover remote networks, maintain updated routing information, choose best paths, and recover from link failures.

What are the three main components of a dynamic routing protocol?

Data structures, routing protocol messages, and algorithms.

Where are routing protocol tables typically stored?

In RAM.

What do routing protocol messages do?

Discover neighbors, exchange routing info, and maintain network accuracy.

What is the role of algorithms in dynamic routing protocols?

Determine the best path and facilitate routing learning.

What is convergence in routing?

When all routers have accurate and complete routing information.

Why is convergence important?

The network cannot fully operate until it has converged.

What affects convergence time?

Speed of routing information propagation and path calculation.

Which protocols are slow to converge?

Older protocols like RIP.

Which protocols converge quickly?

Modern protocols like EIGRP, OSPF, and IS-IS.

When is static routing preferred?

In small networks, stub networks, or for a default route.

What are advantages of static routing?

Simple to configure, predictable, no overhead from routing protocols.

What are disadvantages of static routing?

Manual configuration and no automatic route recovery.

When is dynamic routing preferred?

In large or complex networks needing scalability and redundancy.

What are advantages of dynamic routing?

Automatic updates, scalable, reacts to topology changes.

What are disadvantages of dynamic routing?

Consumes bandwidth and uses router CPU cycles.

What is an IGP?

Interior Gateway Protocol – used for routing within an autonomous system.

What is an EGP?

Exterior Gateway Protocol – used for routing between autonomous systems.

What are examples of IGPs?

RIP, EIGRP, OSPF, IS-IS.

What is the most commonly used EGP?

BGP (Border Gateway Protocol).

What are distance vector routing protocols?

Protocols that use hop count and neighbor information to route traffic.

What are link-state routing protocols?

Protocols that build a complete map of the network topology to determine best paths.

What are examples of distance vector protocols?

RIPv1, RIPv2, EIGRP.

What are examples of link-state protocols?

OSPF, IS-IS.

How does a distance vector protocol operate?

Sends periodic updates to neighbors with route info.

What is the update frequency for RIPv2?

Every 30 seconds.

What UDP port does RIPv2 use?

UDP port 520.

What is the hop limit for RIPv2?

15 hops.

What is RIPng?

IPv6 version of RIPv2 with same 15 hop limitation.

What is the difference between classful and classless protocols?

Classful protocols do not send subnet mask info; classless protocols do.

Which routing protocols are classful?

RIPv1 and IGRP.

Which routing protocols are classless?

RIPv2, OSPF, EIGRP, IS-IS.

What does VLSM stand for?

Variable Length Subnet Masking.

Which protocols support VLSM?

Classless routing protocols.

What is a routing metric?

A value that represents the "cost" of a route.

What is the best route in a routing table?

The one with the lowest metric.

How do routers use metrics?

To determine the most efficient path to a destination.

What is administrative distance?

A trust value for route sources; lower values are more preferred.

What is the AD for directly connected routes?

0

What is the AD for static routes?

1

What is the AD for RIP?

120

What information does a routing table entry contain?

Route source, destination network, next-hop, interface, AD, metric.

How are directly connected routes labeled in the routing table?

With a "C"

How are static routes labeled in the routing table?

With an "S"

How are RIP routes labeled in the routing table?

With an "R"