ROUTING PROTOCOLS

Chapter 12

Intro to Routing & Switching

OBJECTIVES Upon completion of this chapter, you

should be able to:Read a routing tableConfigure a static routeCompare & contrast distance vector and

link state routing protocolsDescribe & configure RIPv1 & v2Describe & configure EIGRPDescribe & configure OSPF

ROUTING

12.1

BASICS Routers can be used to break network

smallerSubnet

To go from router to routerRouting tableFinds route to other networksStatically setDynamically learned

THE ROUTING TABLE Router looks at destination IP & SM

ANDing the destination IP & SM Result is a network # Looks in table for the match & forwards it out

that interface No match= default route, if set

Routing Table has list of networks & paths

THE ROUTING TABLE

READING THE ROUTING TABLE

ACTIVITY Routing Table Homework

STATIC ROUTES

12.2

STATIC ROUTE You telling the router:

“To get to this network, go this way!”

Used so routers do less “thinking” or when there’s only one way out of a networkStub networks or small networks

Same as default route config, but replacing quad zero with destination network address

CONFIGURING THE STATIC ROUTE

ip route destination_network subnet mask next hop ip or outgoing int

R1(config) #ip route 192.168.16.0 255.255.255.0 192.168.15.1

What would be the static route on R2 to reach the ladies’ network?

ACTIVITY Handout: Create static routes

Complete the PT lab togetherConfigure default and static routes

DYNAMIC ROUTES:DISTANCE VECTOR

ROUTING PROTOCOLS

12.3

DYNAMIC ROUTING PROTOCOLS

Maintain tables when changes occurBad cables, interfaces go down, better route

learnedBest route to a network in tableRemoves routes when no longer valid

When all routers agree on topology= converged

Two routers can exchange these tables as long as they use the same protocol

DISTANCE VECTOR ROUTING

Passes updates every so often to connected neighbors

Distance & DirectionMetric (hops, speed, reliability, etc)

DISTANCE VECTOR ROUTING UPDATE METRIC

Directly connected network has an administrative distance of 0

Neighbors update each other & add on how far away it is

Star is 0 away

Star is 1 away

Star is 2 away

Star is 2 away

ACTIVITY 6.1.2.4

Activity for Routing TableDo together on SmartBoard

Create a Diagram from Routing TablesOn paper In groups of 2, create a topology based on

Routing Table

RIP:DISTANCE VECTOR

ROUTING PROTOCOL

12.4

RIP

DV Metric is Hops

Only15 Max; 16 is unreachable (D) Updates every 30 seconds by default

Sends entire routing table (D) If change, update sent immediately (triggered)Slow to converge whole network (D)

Administrative Distance is 120

RIP RIPv1

Doesn’t send subnet mask in updatesClassful subnetting

RIPv2Classless (VLSM) subnettingSupports authenticationOtherwise, same as v1

RIP

CONFIGURE RIP Router(config)#router rip Router (config-router)#version 2 Router(config-router)#network network-number

VERIFYING RIP

Ping Show ip route Show ip protocols Debug ip rip

SHOW IP PROTOCOLS OUTPUT

DISADVANTAGES OF RIP

Increased traffic every 30 seconds

Max hop count of 15Further away is unreachable

Only considers hops, not speed

Possible routing loops

ACTIVITIES Configure RIP

In groups of 2, using the handout

PT Lab Configure & Verify RIP

Use our in class PT lab to configure RIP & verify it.

RIP Homework

REVIEW- 5Q What routing protocol uses hops for its

metric and understands classless routing? RIPv2

What is the AD of RIP? 120

What’s the purpose of entering your router’s network numbers when configuring RIP? To tell it what networks to advertise in updates

A directly connected network has an AD of… 0

A static route has an AD of… 1

EIGRP:ENHANCED DV

ROUTING PROTOCOL

12.5

EIGRP Enhanced Interior Gateway Routing

Protocol Cisco proprietary DV (mix LS & DV)AD of 90Many metrics (bandwidth, delay, load,

reliability)Up to 255 hopsRouting Table, Neighbor Table, Topology TableUpdates on start of router & only when a

change happensVLSM Support

CONFIGURE EIGRP R1(config)#router eigrp 100 R1(config-router)#network

192.168.1.193

Autonomous System #Must be the same on all routers in the

network

CONFIGURE EIGRP

EIGRP TABLES Neighbor Table

Has info about neighbor direct connect routers Topology Table

Built from advertisements of its neighborsContains ALL routes advertised by neighbor

routersDUAL calculates the best path to a destination

and installs it into the routing table Is able to find the best alternate path quickly

when a network change occurs If no alternate route exists it asks its

neighbors to find a new path to the destination

VERIFY EIGRP Show ip route Show ip eigrp neighbors

REVIEW- 4Q How do you configure EIGRP?

Router eigrp as When viewing the routing table, what

letter indicates an EIGRP route?D

What 4 metrics are used for EIGRP?Bandwidth, load, delay, reliability

What algorithm calculates the best path for EIGRP?DUAL

ACTIVITY EIGRP Configuration Lab

TEST Static route RIP EIGRP

OSPF:LINK STATE

ROUTING PROTOCOL

12.6

LINK STATE ROUTING

LINK STATE ROUTING

LINK STATE ROUTING REVIEW

Knows all routes in your network Sends out LSA Makes a Topological database

With info from LSAs Uses the SPF algorithm

Each change causes new calc & database update

Map of network from point of view of the router

Info in tree is used to build the routing table Adds best path to routing table

WHAT IS OSPF? Most popular interior routing protocol

Multi-vendorUnlike Cisco’s EIGRP

Link-stateKnows map of whole networkRouting updates ONLY when change occurs

ALL ABOUT OSPF Uses SPF algorithm Sends updates only when the topology

changesDoes not send periodic updates of the

entire routing table AD of 110 Metric is cost (bandwidth) Fast convergence, no loops Supports VLSM/classless addressing Provides route authentication Multi-vendor (unlike EIGRP)

OSPF DATABASES Neighbor table

List of neighbor routersUnique to each router

Topology tableRepresents the whole networkAll routers have same one

Routing TableRoutes

THE ROUTER ID Tells neighbors who they are Is an IP address as follows:

Highest IP address on a loopback interface (virtual bc it never goes down)

No loopback= highest IP of active interfacesOr assigned manually

HELLO PACKETS Used to establish & maintain adjacency Helps elect Designated Router & BDR Sent every 10 seconds to 224.0.0.5

Dead after 40 seconds To form adjacency:

Hello, dead interval & area # must match

A PROBLEM?

DR/BDR ELECTION One DR/BDR per multi-access area

(switch) All routers will form a full neighbor

adjacency with the DR Link updates sent to DR/BDR

Then forwards to other routersReduces LSA flood/traffic

Chosen by Priority #Highest is DR, next highest is BDRTie breaker is highest Router IDDefault on router is 1; 0 means NEVER!

HOW OSPF WORKS

OSPF AREAS OSPF works with the concepts of areas

Keeps the map of network smaller if you break it up into areas

By default you will always have a single areaNormally this is area 0

You can have multiple areasThey all connect to area 0 (the backbone)

See picture…

REVIEW- 4Q Area 0 is also known as what?

Backbone area If multiple areas are used, where must

they all connect to?Area 0

What do you know about link state protocols?Know whole topology, calculates shortest

path, updates when change happens To maintain connectivity to neighbors,

what do OSPF routers send?Hello packets

REVIEW- 4Q How often are hello packets sent?

Every 10 seconds What happens if you set the priority of

an interface to 0? It will NEVER be the DR/BDR

What is the metric for OSPF?Cost

What is the AD for OSPF?110

CONFIGURING OSPF

12.7

SETUP NETWORK

CONFIGURE THE ROUTERS

Interfaces Add a loopback

interface on each Int loopback 0 Ip address x.x.x.x

y.y.y.y

Student Center- 4.4.4.4 255.255.255.0

Science- 2.2.2.2 Admin- 1.1.1.1

OSPF COMMANDS ScienceBuilding(config)#router ospf 1 ScienceBuilding(config-

router)#network 192.168.23.0 0.0.0.255 area 0

AdminBuilding(config)#router ospf 1 AdminBuilding(config-router)#network

192.168.23.0 0.0.0.255 area 0

Process ID Wildcard mask

WILDCARD MASK Think of a wildcard mask as the inverse of a

subnet mask. The inverse of the subnet mask

255.255.255.252 is 0.0.0.3. To calculate the inverse of the subnet mask,

subtract the subnet mask from 255.255.255.255:

255.255.255.255 – 255.255.255.252 Subtract the sm

0. 0. 0. 3 Wildcard mask

VERIFY StudentCenter#show ip ospf

neighbor

AdminBuilding#show ip protocols

AdminBuilding#show ip route ospf

OSPF DR PRIORITY

ACTIVITY PT Basic OSPF Configuration Lab

REVIEW-4Q If all OSPF routers in a single area have the

same priority, what value does a router use for the OSPF router ID in the absence of a loopback interface? Highest IP address of active interfaces

What will happen if the routers have different process-IDs? Nothing

What is the router ID used for? Election of the DR/BDR

What 2 things does OSPF use to build & maintain its databases? Hello packets & LSAa

WHICH PROTOCOL SHOULD YOU USE??????

DV VS. LINK STATE

SUMMARY OF ROUTING PROTOCOLS

Protocol DV or LS AD Metric Features

RIP v1 DV 120 Hops 15 hops max

RIP v2 DV 120 Hops15 max;VLSM

EIGRP DV-Hybrid 90

Bandwidth, Load, Delay, Reliability

Cisco’s;VLSM

OSPF LS 110 CostMulti-vendor;VLSM

ROUTING

May be multiple routes to same pathUse AD (metrics) to pick best pathLowest AD is best

WHICH ROUTE?

REVIEW- 3Q You are configuring a new router. The

interfaces have been configured but no routing protocols or static routes. What routes would be in the routing table? Directly connected ones

What would cause 2 routers to NOT form an adjacency? The hello, dead, or area #’s don’t match

A router learns of 3 routes to one destination; they are from RIP, EIGRP, and OSPF. Which one will be put in the routing table and why? The EIGRP one. It has the lowest AD.

REVIEW- 4Q After an OSPF network has converged,

what messaging gets exchanged between routers?Hello packets

What is the default AD of OSPF?110

What is the default priority # for Cisco routers in the DR election process?1

What priority # would you set on a router if you did NOT want it to be a DR/BDR?0

REVIEW- 4Q An OSPF router will use a Router ID

based on what?Highest IP of loopback or highest IP of

active int. C 192.168.12.253/30 [110/782] via

192.168.12.233, 00:35:37, Serial 0What does the 782 mean?Cost

What address do hello packets get sent to?224.0.0.5

What does OSPF use to calculate cost?Bandwidth

REVIEW & STUDY Complete the study guide handout

Take the quiz on netacad.com

Jeopardy review

ROUTINGChapter 11

Intro to Routing & Switching