Chapter 7 - Routing

Question 1

What is a router?

Answer 1

A piece of hardware that forward packets based on IP address.

Question 2

Router must use the same type of connection for all routes, such as Ethernet to Ethernet of ATM to ATM.

Answer 2

False, a router can operates on diffrent layer 2 technologies.

Question 3

What technology allows you to share a single public IP address with many computers?

Answer 3

PAT (Port Address Traversal).

Question 4

Distance vector protocols such as RIP rely on what metric to determine the best route?

Answer 4

Hop count.

Question 5

What are the two big advantages to using OSPF over RIP?

Answer 5

Sends only routing table changes, reducing traffic on the network. Chooses route based on link speed, not on hop count.

Question 6

What is the name of the cable that you use to connect the console port on Cisco Router?

Answer 6

The Yost cable.

Question 7

When you are first setting up a new router, you should never plug it innto an existing network.

Answer 7

True.

Question 8

The traceroute utility is usefull for?

Answer 8

Discovering information on the router between you and your destination.

Question 9

In a routing table, what does a 0 octet means?

Answer 9

Any address within this octet to be included.

Question 10

What are the 4 field you’ll find in your routing table?

Answer 10

Destination LAN IP, Subnet Mask, Gateway, Interface.

Question 11

What are the two main NAT technologies?

Answer 11

PAT (port address translation) and port forwarding.

Question 12

What are the 4 metrics that can be used in a routing protocol?

Answer 12

Hop Count, Bandwidth, Delay, Cost.

Question 13

What is the difference between Distance Vector protocols and Path Vector Protocols?

Answer 13

Distance Vector Protocols:
Distance Vector protocols, such as Routing Information Protocol (RIP) and Interior Gateway Routing Protocol (IGRP), use a simple routing algorithm. Routers in a network exchange information about their routing tables with neighboring routers. Each router maintains a vector (list) of distances to reach various network segments, and these distances are periodically exchanged. Routers make decisions based on the cumulative distance and the direction (vector) of the next hop.

Path Vector Protocols:
Path Vector Protocols, like Border Gateway Protocol (BGP), are used in inter-domain routing, particularly on the Internet. Unlike Distance Vector protocols, BGP routers exchange information about paths and policies rather than simple distance metrics. BGP routers maintain a table of paths to different destinations, considering multiple factors like AS-path length, policies, and attributes.

In summary, Distance Vector protocols focus on distance metrics within a domain, while Path Vector protocols, especially BGP, deal with routing between different domains, considering policies and path attributes.

Question 14

Name 3 distance vector protocols

Answer 14

RIPv1, RIPv2 and BGP.

Question 15

When is BGP used?

Answer 15

When connecting between AS (autonomous systems) it is a EGP protocol.

Question 16

What is an AS (Autonomous System)?

Answer 16

An AS is one or more network that are governed by a single dynamic routing protocol within that AS.

Question 17

What is an ASN?

Answer 17

Autonomous System Number. It is a 16 bit number given to an AS by the IANA.

Question 18

What is a link state protocol?

Answer 18

A protocol that favors route based on bandwidth rather than hopcount.

Question 19

What are the 2 linkstate protocols?

Answer 19

OSPF and IS-IS.

Question 20

What is EIGRP?

Answer 20

A routing protocol developped by Cisco. It is an advanced distance vector protocol.

Question 21

What is route redistribution?

Answer 21

Route redistribution is a process in networking where routing information learned from one routing protocol is shared or injected into another routing protocol. This is typically done at the boundary between different routing domains or when transitioning from one routing protocol to another. The goal is to enable routers running different routing protocols to exchange routing information and reach network destinations that are learned through diverse routing mechanisms.

For example, if a network is using both OSPF (Open Shortest Path First) and EIGRP (Enhanced Interior Gateway Routing Protocol), route redistribution allows routers in one protocol to learn about and use routes from the other protocol. The process involves converting routing information from one protocol into a format suitable for the receiving protocol.

Careful planning and configuration are required when implementing route redistribution to avoid routing loops and ensure a coherent and stable network. Misconfigurations can lead to suboptimal routing or network instability.

Question 22

How can you connect to a router?

Answer 22

Directely (serial or Yost), Via its interface or through a Network Management Software.