Chapter 6 Inter -VLAN Routing - mars.merhot.dkmars.merhot.dk/mediawiki/images/8/8d/Expl_Sw_chapter_06_Inter_VLAN.pdfCCNA3-1 Chapter 6 Chapter 6 Inter -VLAN Routing CCNA3-2 Chapter

CCNA3-1 Chapter 6

Chapter 6Chapter 6

InterInter--VLAN RoutingVLAN 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 InterIntroducing Inter--VLAN RoutingVLAN Routing

CCNA3-4 Chapter 6

•• What is InterWhat is Inter--VLAN Routing?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.

•• InterInter--VLAN routingVLAN 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 InterInter--VLAN Routing.VLAN Routing.

•• RouterRouter--onon--aa--stickstick InterInter--VLAN Routing.VLAN Routing.

•• Switch BasedSwitch Based InterInter--VLAN Routing.VLAN Routing.


CCNA3-6 Chapter 6

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

•• One router interface per VLAN.One router interface per VLAN.


VLAN TaggedVLAN VLAN

TaggedTagged

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

Tagremoved

TagTagremovedremoved

CCNA3-7 Chapter 6

•• RouterRouter--onon--aa--stick Interstick Inter--VLAN Routing:VLAN Routing:

•• One router interface forOne router interface for all VLANsall VLANs..


VLAN TaggedVLAN VLAN

TaggedTagged

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

Tagremoved


CCNA3-8 Chapter 6

•• Layer 3 Switch InterLayer 3 Switch Inter--VLAN Routing:VLAN Routing:

•• UsesUses Switch Virtual Interfaces (SVI)Switch Virtual Interfaces (SVI) to retagto retagthe frame.the frame.


VLAN Tagged

(10)

VLAN VLAN TaggedTagged

(10)(10)

Tagremoved


CCNA3-9 Chapter 6


•• Traditional routing requires routers to have Traditional routing requires routers to have multiple multiple physical interfacesphysical interfaces to facilitate interto facilitate inter--VLAN routing. 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 InterTraditional Inter--VLAN RoutingVLAN Routing


TaggedVLAN 10TaggedTagged

VLAN 10VLAN 10Tag

RemovedTagTag

RemovedRemoved

Router Responds

Router Router RespondsResponds

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

Routing table:Routing table:172.17.10.0 172.17.10.0 –– F0/0F0/0172.17.30.0 172.17.30.0 –– F0/1F0/1

Router tagsthe frame

for VLAN 30And switches itto 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 InterTraditional Inter--VLAN RoutingVLAN Routing

CCNA3-12 Chapter 6


•• Traditional interTraditional inter--VLANVLANrouting using physicalrouting using physicalinterfaces interfaces does have adoes have alimitationlimitation. .

•• As the number of VLANsAs the number of VLANsincreasesincreases on a network, theon 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


•• Subinterfaces:Subinterfaces:

•• Overcomes the hardware limitation of a router. Overcomes the hardware limitation of a router.

•• Subinterfaces are softwareSubinterfaces are software--based virtual interfaces 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 RoutingRouterRouter--onon--aa--stick Interstick Inter--VLAN RoutingVLAN Routing


VLAN 10VLAN 10Tag

RemovedTagTag

RemovedRemoved

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

Routing table:Routing table:172.17.10.0 172.17.10.0 –– F0/0.10F0/0.10172.17.30.0 172.17.30.0 –– F0/0.30F0/0.30


VLAN 30VLAN 30

TagRemoved

TagTagRemovedRemovedTagged

VLAN 30TaggedTagged

VLAN 30VLAN 30Tag

RemovedTagTag

RemovedRemoved

CCNA3-15 Chapter 6


•• 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


•• 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


•• 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(configconfig--subifsubif)#)#encapsulation dot1qencapsulation dot1q vlanvlan--idid


CCNA3-18 Chapter 6


•• 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(configconfig--subifsubif)#)#ip address ip address [address] [mask][address] [mask]


CCNA3-19 Chapter 6


•• 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 associatedsubinterfacessubinterfaces are enabled.are enabled.

R1(R1(configconfig--ifif)#)#no shutdownno shutdown


CCNA3-20 Chapter 6




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

VLAN 30VLAN 30VLAN 30



Enable InterfacesEnable InterfacesEnable Interfaces

CCNA3-21 Chapter 6




Planning!Planning!Planning!

CCNA3-22 Chapter 6

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


CCNA3-23 Chapter 6


Configuring InterConfiguring Inter--VLAN RoutingVLAN Routing(Putting It All Together)(Putting It All Together)

CCNA3-24 Chapter 6


Configuring InterConfiguring Inter--VLAN RoutingVLAN Routing

CCNA3-25 Chapter 6



CCNA3-26 Chapter 6



CCNA3-27 Chapter 6



VLANs

VLANVLANss

TrunkTrunkTrunk

InterfacesInterfacesInterfacesVLANsVLANsVLANs

Trunk in Native VLAN

Trunk in Trunk in Native VLANNative VLAN

CCNA3-28 Chapter 6





Enable All Subinterfaces

Enable All Enable All SubinterfacesSubinterfaces

CCNA3-29 Chapter 6


Troubleshooting InterTroubleshooting Inter--VLAN RoutingVLAN Routing

CCNA3-30 Chapter 6

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

cannot communicate with the 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 the default VLAN.

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 10

CCNA3-31 Chapter 6

•• Switch Configuration Issues:Switch Configuration Issues:


Each of the configured subinterfaces is unable to

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.

Interface F0/5 is still in the default VLAN.

Interface F0/5 is still in Interface F0/5 is still in the default VLAN.the default VLAN.

switchport mode trunk

switchport mode switchport mode trunktrunk

CCNA3-32 Chapter 6

•• Router Configuration Issues:Router Configuration Issues:


PC1 cannot communicate with the router interface and the router

cannot route to VLAN 30.

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 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.

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

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

CCNA3-33 Chapter 6

•• Router Configuration Issues:Router Configuration Issues:

Configuring InterConfiguring Inter--VLAN RoutingVLAN RoutingPC1 cannot communicate with the

router interface and the router cannot route to VLAN 30.

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.

CCNA3-34 Chapter 6

•• IP Addressing Issues:IP Addressing Issues:


Incorrect IP address for subnet

172.16.10.0/24.

Incorrect IP address Incorrect IP address for subnet for subnet

172.16.10.0/24.172.16.10.0/24.Incorrect IP address

for subnet 172.16.10.0/24.

Incorrect IP address Incorrect IP address for subnet for subnet

172.16.10.0/24.172.16.10.0/24.

Incorrect subnet mask for 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.

Documents

Chapter 6 Inter -VLAN Routing - mars.merhot.dkmars.merhot.dk/mediawiki/images/8/8d/Expl_Sw_chapter_06_Inter_VLAN.pdfCCNA3-1 Chapter 6 Chapter 6 Inter -VLAN Routing CCNA3-2 Chapter