Dynamiska Routingprotokoll

Question 1

What is the difference between IPG and EGP routing protocol?

Answer 1

GP → used for routing within an AS (RIP, EIGRP, OSP, IS-IS)

EGP → used for routing between AS (BGP)

Question 2

What does distance vector routing protocol mean?

Answer 2

Distance vector means that routes are advertised by providing
two characteristics which are Distance and Vector:

• Distance - Identifies how far it is to the destination
network based on a metric such as hop count, cost,
bandwidth, delay.

• Vector - Specifies the direction of the next-hop
router or exit interface to reach the destination.

Question 3

How does a Link State Routing Protocol work?

Answer 3

Uses link-state info to;

• create topology map
• select best path

The technique was later adapted for use in the link-state routing protocols OSPF and IS-IS

Question 4

Does Link State use periodic updates?

Answer 4

No, updates only sent when there is a change in the topology.

Question 5

What is the difference between Classful and Classless routing protocol?

Answer 5

• Classful → do not send mask info in the updates, does not support VLSM
• Classless → Include subnet mask info, supports VLSM.

Question 6

What metrics are used by protocols?

Answer 6

• RIP → hop count
• OSPF → Cost based on cumulative bandwidth
• EIGRP → Bandwidth, delay, load, reliability

Question 7

What does Convergence time mean?

Answer 7

The time it takes routers to share info, calculate best paths, and update routing tables. (Converged network = all routers have complete info regarding the network)

Question 8

What is the hop limit for RIPv2?

Answer 8

15 hops

Question 9

What is the difference between RIP and RIPv2

Answer 9

• Both have the same hop limit (15)

RIP
- RIP Routing updates broadcasted (255.255.255.255) every 30 seconds

RIPv2
• Classless routing protocol - supports VLSM and CIDR
• Increased efficiency – sends updates to multicast address 224.0.0.9
• Reduced routing entries - supports manual route summarization
• Secure - supports authentication

Question 10

What does EIGRP include?

Answer 10

Bounded triggered updates – sends updates only to routers that need it.

• Hello keepalive mechanism - Hello messages are periodically exchanged to maintain adjacencies.
• Maintains a topology table - maintains all the routes received from neighbors (not only the best paths) in a topology table.
• Multiple network layer protocol support – uses Protocol Dependent Modules (PDM) to support layer 3 protocols.

Question 11

What is the process behind link-state?

Answer 11

• Each router learns its own connected networks
• Each router is responsible for saying “hello” to its neighbors
• Each router builds a Link-State Packet (LSP) containing the state of each directly connected network.
• Each router floods LSP to all neighbors.
• Each router uses this info to build the topology map with best path to each destination.