Module 6

Routing and Routing Protocols

Routing… Nothing more than directions for getting

from one network to another. _________________________, for traffic going

through a network cloud, occurs at the network layer

A router makes decisions based upon the ________________________________ ___________________________________________________________________ routers must learn the direction to remote

networks by either static or dynamic routing

Dynamic v. Static Routing _______________________________

______________________________________________________________.

Static routing is most often used with stub networks where only one path exists to the destination.

• _______________ ________________________________

•Allows for increased security

Static route configuration using outgoing interface

Going to… Mask of destination network

Interface on Hoboken router closet to destination network

Static route configuration using next-hop IP address

Going to… Mask of destination network

Serial IP address on ADJACENT router closet to destination network

Difference in Configurations _______________ assigned to the route by the

router (Hoboken) or network administrator as it is placed in the routing table. Admin. Distance- _____________________

____________________________________________ • Used as a means to find the best path• ____________________________________________

Outgoing interface option Admin distance = 0

Next-hop IP address Admin distance = 1

Static route cont… Customize the _________________

_______________ by adding it to the end of the “ip route” command waycross(config)#ip route 172.16.3.0

255.255.255.0 172.16.4.1 _______ If the router cannot reach the

outgoing interface programmed ____________________________

______________________________

Default Routes A _____________________________ _______________

that all routers on a network can send packets to if they __ ____________________________________________________________

• The default route concept assumes that data forwarded along the default route will eventually encounter a router that DOES know the path to the destination.

Default route forwarding Special static route Command

Issued in global config mode ip route _____________________ [next-

hop-address | outgoing interface]

Verification and troubleshooting

“_________________________” used to verify that the static route has

been entered correctly “__________________________”

Used to verify that the route that was configured is in the _______________

What troubleshooting techniques can we use to verify connectivity via a static route?

Dynamic v. Static Routing Dynamic routing refers to the process of

_____________________________________________________________.

Routing protocols enable dynamic routing where multiple paths to the same destination exist.

Routed v. Routing Protocols Routed (or Routable) protocols are

protocols that ________________ __________________________________________________ using a hierarchical addressing scheme. Carry packaged data

Operate at the ________________ Examples include ________________

______________________________

Routed v. Routing Protocols

A routing protocol ____________ __________________________________________________________. Routers use routing protocols to _______

______________________. These maps allow ___________________________ ____________________. Maps become part of the router’s routing table.

Allow routers to make decisions Examples of routing protocols include:

_______________________________

Autonomous System (AS) Collection of networks _______________

_________________________ strategy. AS is viewed as a single entity ________________________ must be used

between Autonomous systems Identified by a 16 bit number that _________

_________________ or can be assigned by the network administrator

Some routing protocols required the use of an AS

More on routing protocols Goal of a routing protocol is to ____

____________________________. Contains the learned networks and

associated ports for those networks ______________________________

_____________________________ _____________________________________

__________________

Example of a routing table

This is the interface number, there could be any number of hosts on network 1.0

Routing table used for path determination and packet switching

More on Dynamic routing Offers _______________________ Dynamic routing depends on :

_______________________________________________________

____________________________, to other routers 

Routing protocols dictate how communication with neighbors takes place

Dynamic routing details cont… The best path to a destination, is

determined by _______________ ____________________ called… A _______________________ _______________________________

• The fewer the stop signs- the better

Metrics calculated based on different __________________________

Characteristics used to generate the Metric

___________ - the data capacity of a link; delay ____________ - the amount of activity on a

network resource such as a router or link reliability _______________ - the number of routers a

packet must travel through before reaching its destination

ticks ________________ - an arbitrary value assigned

by a network administrator

In this example, the metric is comprised of four different characteristics.

Convergence At the time of convergence __________

_______________________________________________________________

Every time there is a topology change, routing protocols _________________ ________________________________________________________________

The time of convergence varies depending upon the routing protocol being used. The _______________________________

Distance-vector Routing Determines the route based on the direction

(vector) and distance to the destination Each router receives _____________

_____________________________________________________________________

Distance-vector protocols _____________ _____________________________________________________________________

Topology change updates proceed step-by-step from router to router as in the discovery process

Distance Vector example

___________ seen in Distance Vector routing protocols

____________________________ Can cause Routing Loops

• Occurs when new updated information causes inconsistent routing entries.

Internet Cloud

Router X

Link-state (SPF) Routing AKA “shortest path first” algorithm __________________________________________

_________________________ Link-state protocols maintain complex

__________________________________________________________________.

Each time a new route is added or a route goes down, each router receives a message and then recalculates a spanning tree algorithm and updates its topology database.

Link-state cont… Link-state routing algorithm _______________

____________________________________ Link-state advertisements (_________)

________________________________________________________________________.

_________________________________ _________________________________

______________________ The router that first becomes aware of a

topology change forwards the information to _________________________________________________________________________

Disadvantages of Link-State Processing requirements

_____________________________________________________________________________

Bandwidth Uses ____________________________________

_______________________________________ After initial flood, uses ____________________

__________________________________________ If LSA distribution to all routers is not done

correctly, link-state routing ______________ __________________________________

Configuring Routing Example

GAD(config)#router igrp 2GAD(config-router)#network 172.16.0.0

Global config modeRouting config mode

Autonomous system # required for IGRP, EIGRP

Necessary to enable the routing process to determine which interfaces participate in the sending and receiving of routing updates. Network addresses only listed here- NOT subnets

What are the routing protocols? RIP

______________________________________________ ______________ is used as the metric for path selection. If the hop count is greater than ___, the packet is discarded. Routing ________________________________, by default.

IGRP Cisco's ________________________________ ________________________________________ are used to create a

composite metric. Routing _________________________________, by default.

EIGRP Cisco’s ___________________________________________ Uses ______________________________. Uses a _________________________________________. Routing updates are broadcast every ____________ or as

________________________ changes.

More routing protocols…

OSPF A ____________________________ used to

calculate the lowest cost to a destination. Routing ___________________________ as

topology changes occur. BGP

It is a ______________________________ ______________________________

Used ________________ or ISPs and clients. Used to route ________________________

____________________________________

Summary comparison

DISTANCE-VECTOR LINK-STATE

Views network topology from neighbor’s perspective

Gets common view of entire network topology

Adds distance vectors from router to router

Calculates the shortest path to other routers

Frequent, periodic updates: slow convergence

Event triggered updates: fast convergence

Passes copies of routing tables to neighbors

Passes link-state routing updates to all routers in the system.

One Lab for chapter 6

Configuring Static RoutesLab 6.1.6