ccna3-1 chapter 6 inter-vlan routing. ccna3-2 chapter 6 note for instructors these presentations are...

CCNA3-1 Chapter 6

Chapter 6Chapter 6

Inter-VLAN RoutingInter-VLAN Routing

CCNA3-2 Chapter 6

Note for InstructorsNote for Instructors

• These presentations are the result of a collaboration among These presentations are the result of a collaboration among the instructors at St. Clair College in Windsor, Ontario.the instructors at St. Clair College in Windsor, Ontario.

• Thanks must go out to Rick Graziani of Cabrillo College. His Thanks must go out to Rick Graziani of Cabrillo College. His material and additional information was used as a reference material and additional information was used as a reference in their creation.in their creation.

• If anyone finds any errors or omissions, please let me know If anyone finds any errors or omissions, please let me know at: at:

• [email protected]@stclaircollege.ca.

CCNA3-3 Chapter 6


Introducing Inter-VLAN RoutingIntroducing Inter-VLAN Routing

CCNA3-4 Chapter 6

• What is Inter-VLAN Routing?What is Inter-VLAN Routing?• Each VLAN is a Each VLAN is a unique broadcast domainunique broadcast domain..

• Computers on separate VLANs are, Computers on separate VLANs are, by defaultby default, not , not able to communicate.able to communicate.

• Each VLAN is a Each VLAN is a unique IP subnetworkunique IP subnetwork..

• To allow VLANs to communicate, we need a router to To allow VLANs to communicate, we need a router to communicate among separate broadcast domains and communicate among separate broadcast domains and unique IP subnetworks.unique IP subnetworks.

• Inter-VLAN routingInter-VLAN routing, then, , then, is a process of forwarding traffic is a process of forwarding traffic from one VLAN to another VLAN using a routerfrom one VLAN to another VLAN using a router. .


CCNA3-5 Chapter 6

• Methods:Methods:• TraditionalTraditional Inter-VLAN Routing. Inter-VLAN Routing.• Router-on-a-stickRouter-on-a-stick Inter-VLAN Routing. Inter-VLAN Routing.• Switch BasedSwitch Based Inter-VLAN Routing. Inter-VLAN Routing.


CCNA3-6 Chapter 6

• Traditional Inter-VLAN Routing:Traditional Inter-VLAN Routing:• One router interface per VLAN.One router interface per VLAN.


VLAN VLAN TaggedTaggedVLAN VLAN

TaggedTagged

Internally Routed to Internally Routed to the proper subnet.the proper subnet.Internally Routed to Internally Routed to the proper subnet.the proper subnet.

TagTagremovedremoved


CCNA3-7 Chapter 6

• Router-on-a-stick Inter-VLAN Routing:Router-on-a-stick Inter-VLAN Routing:• One router interface forOne router interface for all VLANs all VLANs..


VLAN VLAN TaggedTaggedVLAN VLAN

TaggedTagged

Internally Routed to Internally Routed to the proper subnet.the proper subnet.Internally Routed to Internally Routed to the proper subnet.the proper subnet.



CCNA3-8 Chapter 6

• Layer 3 Switch Inter-VLAN Routing:Layer 3 Switch Inter-VLAN Routing:• UsesUses Switch Virtual Interfaces (SVI) Switch Virtual Interfaces (SVI) to retag to retag

the frame.the frame.


VLAN VLAN TaggedTagged

(10)(10)

VLAN VLAN TaggedTagged

(10)(10)



CCNA3-9 Chapter 6

• Traditional Inter-VLAN Routing:Traditional Inter-VLAN Routing:• Traditional routing requires routers to have Traditional routing requires routers to have multiple multiple

physical interfacesphysical interfaces to facilitate inter-VLAN routing. to facilitate inter-VLAN routing. • Each interface is also configured with an Each interface is also configured with an IP address for IP address for

the subnet associated with the particular VLANthe subnet associated with the particular VLAN that it is that it is connected to. connected to.

• In this configuration, network devices can use the In this configuration, network devices can use the router router as a gatewayas a gateway to access the devices connected to the to access the devices connected to the other VLANs.other VLANs.

Interfaces and SubinterfacesInterfaces and Subinterfaces

CCNA3-10 Chapter 6

Traditional Inter-VLAN RoutingTraditional Inter-VLAN RoutingTraditional Inter-VLAN RoutingTraditional Inter-VLAN Routing


TaggedTaggedVLAN 10VLAN 10TaggedTagged

VLAN 10VLAN 10TagTag

RemovedRemovedTagTag

RemovedRemoved

Router Router RespondsResponds

Router Router RespondsResponds

Routing table:Routing table:172.17.10.0 – F0/0172.17.10.0 – F0/0172.17.30.0 – F0/1172.17.30.0 – F0/1

Routing table:Routing table:172.17.10.0 – F0/0172.17.10.0 – F0/0172.17.30.0 – F0/1172.17.30.0 – F0/1

Router tagsRouter tagsthe framethe frame

for VLAN 30for VLAN 30And switches itAnd switches itto Port F0/1. to Port F0/1.

Router tagsRouter tagsthe framethe frame

for VLAN 30for VLAN 30And switches itAnd switches itto Port F0/1. to Port F0/1.

CCNA3-11 Chapter 6


Traditional Inter-VLAN RoutingTraditional Inter-VLAN RoutingTraditional Inter-VLAN RoutingTraditional Inter-VLAN Routing

CCNA3-12 Chapter 6

• Traditional Inter-VLAN Routing:Traditional Inter-VLAN Routing:• Traditional inter-VLANTraditional inter-VLAN

routing using physicalrouting using physicalinterfaces interfaces does have adoes have alimitationlimitation. .

• As the number of VLANsAs the number of VLANsincreasesincreases on a network, the on a network, thephysical approach of having one router interface per physical approach of having one router interface per VLAN quickly becomes hindered by the physical VLAN quickly becomes hindered by the physical hardware limitations of a router. hardware limitations of a router.

• Routers have a limited number of physical interfacesRouters have a limited number of physical interfaces that that they can use to connect to different VLANs.they can use to connect to different VLANs.

• It is very expensive to add an Ethernet Interface. It is very expensive to add an Ethernet Interface.


CCNA3-13 Chapter 6

• Router-on-a-stick Inter-VLAN Routing:Router-on-a-stick Inter-VLAN Routing:• Subinterfaces:Subinterfaces:

• Overcomes the hardware limitation of a router. Overcomes the hardware limitation of a router. • Subinterfaces are software-based virtual interfaces Subinterfaces are software-based virtual interfaces

that are assigned to physical interfacesthat are assigned to physical interfaces. . • Each subinterface is configured with its Each subinterface is configured with its own IP own IP

address, subnet mask, and unique VLAN assignmentaddress, subnet mask, and unique VLAN assignment..• Connected to a Connected to a switch trunk linkswitch trunk link. . • Functionally the same as using the traditional routing Functionally the same as using the traditional routing

model.model.


CCNA3-14 Chapter 6


Router-on-a-stick Inter-VLAN RoutingRouter-on-a-stick Inter-VLAN RoutingRouter-on-a-stick Inter-VLAN RoutingRouter-on-a-stick Inter-VLAN Routing




RemovedRemoved

Routing table:Routing table:172.17.10.0 – F0/0.10172.17.10.0 – F0/0.10172.17.30.0 – F0/0.30172.17.30.0 – F0/0.30

Routing table:Routing table:172.17.10.0 – F0/0.10172.17.10.0 – F0/0.10172.17.30.0 – F0/0.30172.17.30.0 – F0/0.30


VLAN 30VLAN 30

TagTagRemovedRemoved

TagTagRemovedRemovedTaggedTagged

VLAN 30VLAN 30TaggedTagged



RemovedRemoved

CCNA3-15 Chapter 6

• Router-on-a-stick Inter-VLAN Routing:Router-on-a-stick Inter-VLAN Routing:• Configuring Subinterfaces:Configuring Subinterfaces:

• Similar to configuring physical interfaces.Similar to configuring physical interfaces.• Create the subinterface.Create the subinterface.• Assign it to a VLAN.Assign it to a VLAN.• Assign an IP Address.Assign an IP Address.• Enable the interface.Enable the interface.


CCNA3-16 Chapter 6

• Router-on-a-stick Inter-VLAN Routing:Router-on-a-stick Inter-VLAN Routing:• Create the subinterface:Create the subinterface:

• The syntax for the subinterface is always the The syntax for the subinterface is always the physical physical interfaceinterface, followed by a , followed by a periodperiod and a and a subinterface subinterface numbernumber. .

• The subinterface number is configurable, but it is The subinterface number is configurable, but it is typically associated to reflect the VLAN numbertypically associated to reflect the VLAN number..

R1(config)#R1(config)#interfaceinterface [interface].nn[interface].nn

NOTE: NOTE: The management VLAN must also be The management VLAN must also be configured if you wish to use it on multiple switches configured if you wish to use it on multiple switches that are not directly connected by trunk links.that are not directly connected by trunk links.


CCNA3-17 Chapter 6

• Router-on-a-stick Inter-VLAN Routing:Router-on-a-stick Inter-VLAN Routing:• Assign it to a VLAN:Assign it to a VLAN:

• Before assigning an IP Address, the interface must to Before assigning an IP Address, the interface must to be configured to operate be configured to operate on a specific VLANon a specific VLAN using the using the proper proper encapsulationencapsulation..

R1(R1(config-subifconfig-subif)#)#encapsulation dot1qencapsulation dot1q vlan-idvlan-id


CCNA3-18 Chapter 6

• Router-on-a-stick Inter-VLAN Routing:Router-on-a-stick Inter-VLAN Routing:• Assign an IP Address:Assign an IP Address:

• The IP Address assigned here will become the The IP Address assigned here will become the default default gatewaygateway for that VLAN. for that VLAN.

R1(R1(config-subifconfig-subif)#)#ip address ip address [address] [mask][address] [mask]


CCNA3-19 Chapter 6

• Router-on-a-stick Inter-VLAN Routing:Router-on-a-stick Inter-VLAN Routing:• Enable the interface:Enable the interface:

• Subinterfaces are not enabled individually.Subinterfaces are not enabled individually.• When the physical interface is enabled, When the physical interface is enabled, all associatedall associated

subinterfacessubinterfaces are enabled. are enabled.

R1(R1(config-ifconfig-if)#)#no shutdownno shutdown


CCNA3-20 Chapter 6



VLAN 10VLAN 10VLAN 10VLAN 10VLAN 10VLAN 10VLAN 10VLAN 10

VLAN 30VLAN 30VLAN 30VLAN 30



Enable InterfacesEnable InterfacesEnable InterfacesEnable Interfaces

CCNA3-21 Chapter 6



Planning!Planning!Planning!Planning!

CCNA3-22 Chapter 6

• Router Interface and Subinterface Comparison:Router Interface and Subinterface Comparison:


CCNA3-23 Chapter 6


Configuring Inter-VLAN RoutingConfiguring Inter-VLAN Routing(Putting It All Together)(Putting It All Together)

CCNA3-24 Chapter 6

• Traditional Inter-VLAN Routing:Traditional Inter-VLAN Routing:

Configuring Inter-VLAN RoutingConfiguring Inter-VLAN Routing

CCNA3-25 Chapter 6



CCNA3-26 Chapter 6



CCNA3-27 Chapter 6

• Router-on-a-stick Inter-VLAN Routing:Router-on-a-stick Inter-VLAN Routing:


VLANsVLANsVLANsVLANs

TrunkTrunkTrunkTrunk

InterfacesInterfacesInterfacesInterfaces

VLANsVLANsVLANsVLANs

Trunk in Trunk in Native VLANNative VLAN

Trunk in Trunk in Native VLANNative VLAN

CCNA3-28 Chapter 6

• Router-on-a-stick Inter-VLAN Routing:Router-on-a-stick Inter-VLAN Routing:




Enable All Enable All SubinterfacesSubinterfaces

Enable All Enable All SubinterfacesSubinterfaces

CCNA3-29 Chapter 6


Troubleshooting Inter-VLAN RoutingTroubleshooting Inter-VLAN Routing

CCNA3-30 Chapter 6

• Switch Configuration Issues:Switch Configuration Issues:VLAN 30 is working but VLAN 10 VLAN 30 is working but VLAN 10

cannot communicate with the cannot communicate with the router or VLAN 30.router or VLAN 30.

VLAN 30 is working but VLAN 10 VLAN 30 is working but VLAN 10 cannot communicate with the cannot communicate with the

router or VLAN 30.router or VLAN 30.


Interface F0/4 is still in Interface F0/4 is still in the default VLAN.the default VLAN.


switchport access vlan 10switchport access vlan 10switchport access vlan 10switchport access vlan 10

CCNA3-31 Chapter 6

• Switch Configuration Issues:Switch Configuration Issues:


Each of the configured Each of the configured subinterfaces is unable to subinterfaces is unable to

send or receive VLAN traffic.send or receive VLAN traffic.

Each of the configured Each of the configured subinterfaces is unable to subinterfaces is unable to

send or receive VLAN traffic.send or receive VLAN traffic.



switchport mode trunkswitchport mode trunkswitchport mode trunkswitchport mode trunk

CCNA3-32 Chapter 6

• Router Configuration Issues:Router Configuration Issues:


PC1 cannot communicate with the PC1 cannot communicate with the router interface and the router router interface and the router

cannot route to VLAN 30.cannot route to VLAN 30.



Switch port F0/4 is Switch port F0/4 is for VLAN 10.for VLAN 10.

Switch port F0/4 is Switch port F0/4 is for VLAN 10.for VLAN 10.

Move the cable from F0/9 to F0/4.Move the cable from F0/9 to F0/4.Move the cable from F0/9 to F0/4.Move the cable from F0/9 to F0/4.

One of the most common One of the most common mistakes in Inter-VLAN routing.mistakes in Inter-VLAN routing.

One of the most common One of the most common mistakes in Inter-VLAN routing.mistakes in Inter-VLAN routing.

Move the cable from F0/9 to F0/4.Move the cable from F0/9 to F0/4.Move the cable from F0/9 to F0/4.Move the cable from F0/9 to F0/4.

CCNA3-33 Chapter 6

• Router Configuration Issues:Router Configuration Issues:

Configuring Inter-VLAN RoutingConfiguring Inter-VLAN RoutingPC1 cannot communicate with the PC1 cannot communicate with the

router interface and the router router interface and the router cannot route to VLAN 30.cannot route to VLAN 30.



CCNA3-34 Chapter 6

• IP Addressing Issues:IP Addressing Issues:


Incorrect IP address for Incorrect IP address for subnet 172.16.10.0/24.subnet 172.16.10.0/24.Incorrect IP address for Incorrect IP address for subnet 172.16.10.0/24.subnet 172.16.10.0/24.

Incorrect IP address for Incorrect IP address for subnet 172.16.10.0/24.subnet 172.16.10.0/24.Incorrect IP address for Incorrect IP address for subnet 172.16.10.0/24.subnet 172.16.10.0/24.Incorrect subnet mask for Incorrect subnet mask for subnet 172.16.10.0/24.subnet 172.16.10.0/24.

Incorrect subnet mask for Incorrect subnet mask for subnet 172.16.10.0/24.subnet 172.16.10.0/24.

PC1 cannot communicate.PC1 cannot communicate.PC1 cannot communicate.PC1 cannot communicate.

ccna3-1 chapter 6 inter-vlan routing. ccna3-2 chapter 6 note for instructors these presentations are...

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