Home > Articles > Implementing Inter-VLAN Routing

Implementing Inter-VLAN Routing

By Scott Empson, Patrick Gargano.
Sample Chapter is provided courtesy of Cisco Press.
Date: Jun 3, 2020.

Chapter Information

Inter-VLAN Communication Using an External Router: Router-on-a-Stick
Inter-VLAN Communication Tips
Inter-VLAN Communication on a Multilayer Switch Through a Switch Virtual Interface
Configuration Example: Inter-VLAN Communication
Configuration Example: IPv6 Inter-VLAN Communication

Chapter Description

The CCNP and CCIE Enterprise Core & CCNP Enterprise Advanced Routing Portable Command Guide is a fully updated quick reference resource to help you memorize commands and concepts for CCNP or CCIE certifications. In this sample chapter, you will review information and commands related to implementing inter-VLAN routing.

From the Book

CCNP and CCIE Enterprise Core & CCNP Enterprise Advanced Routing Portable Command Guide: All ENCOR (350-401) and ENARSI (300-410) Commands in One Compact, Portable Resource

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Configuration Example: Inter-VLAN Communication

Figure 3-1 illustrates the network topology for the configuration that follows, which shows how to configure inter-VLAN communication using commands covered in this chapter. Some commands used in this configuration are from other chapters.

Figure 3-1 Network Topology for Inter-VLAN Communication Configuration

ISP Router

`Router> enable`	Moves to privileged EXEC mode
`Router># configure terminal`	Moves to global configuration mode
`Router(config)# hostname ISP`	Sets the host name
`ISP(config)# interface loopback 0`	Moves to interface configuration mode
`ISP(config-if)# description simulated address representing remote website`	Sets the locally significant interface description
`ISP(config-if)# ip address 198.133.219.1 255.255.255.0`	Assigns an IP address and netmask
`ISP(config-if)# interface serial 0/0/0`	Moves to interface configuration mode
`ISP(config-if)# description WAN link to the Corporate Router`	Sets the locally significant interface description
`ISP(config-if)# ip address 192.31.7.5 255.255.255.252`	Assigns an IP address and netmask
`ISP(config-if)# clock rate 4000000`	Assigns a clock rate to the interface; DCE cable is plugged into this interface
`ISP(config-if)# no shutdown`	Enables the interface
`ISP(config-if)# exit`	Returns to global configuration mode
`ISP(config-if)# router eigrp 10`	Creates Enhanced Interior Gateway Routing Protocol (EIGRP) routing process 10
`ISP(config-router)# network 198.133.219.0 0.0.0.255`	Advertises directly connected networks
`ISP(config-router)# network 192.31.7.0 0.0.0.255`	Advertises directly connected networks
`ISP(config-router)# end`	Returns to privileged EXEC mode
`ISP# copy running-config startup-config`	Saves the configuration to NVRAM

CORP Router

`Router> enable`	Moves to privileged EXEC mode
`Router># configure terminal`	Moves to global configuration mode
`Router(config)# hostname CORP`	Sets the host name
`CORP(config)# no ip domain-lookup`	Turns off Domain Name System (DNS) resolution to avoid wait time due to DNS lookup of spelling errors
`CORP(config)# interface serial 0/0/0`	Moves to interface configuration mode
`CORP(config-if)# description link to ISP`	Sets the locally significant interface description
`CORP(config-if)# ip address 192.31.7.6 255.255.255.252`	Assigns an IP address and netmask
`CORP(config-if)# no shutdown`	Enables the interface
`CORP(config)# interface fastethernet 0/1`	Moves to interface configuration mode
`CORP(config-if)# description link to L3Switch1`	Sets the locally significant interface description
`CORP(config-if)# ip address 172.31.1.5 255.255.255.252`	Assigns an IP address and netmask
`CORP(config-if)# no shutdown`	Enables the interface
`CORP(config-if)# exit`	Returns to global configuration mode
`CORP(config)# interface fastethernet 0/0`	Enters interface configuration mode
`CORP(config-if)# no shutdown`	Enables the interface
`CORP(config-if)# interface fastethernet 0/0.1`	Creates a virtual subinterface and moves to subinterface configuration mode
`CORP(config-subif)# description Management VLAN 1 - Native VLAN`	Sets the locally significant interface description
`CORP(config-subif)# encapsulation dot1q 1 native`	Assigns VLAN 1 to this subinterface. VLAN 1 is the native VLAN. This subinterface uses the 802.1q protocol
`CORP(config-subif)# ip address 192.168.1.1 255.255.255.0`	Assigns an IP address and netmask
`CORP(config-subif)# interface fastethernet 0/0.10`	Creates a virtual subinterface and moves to subinterface configuration mode
`CORP(config-subif)# description Sales VLAN 10`	Sets the locally significant interface description
`CORP(config-subif)# encapsulation dot1q 10`	Assigns VLAN 10 to this subinterface. This subinterface uses the 802.1q protocol
`CORP(config-subif)# ip address 192.168.10.1 255.255.255.0`	Assigns an IP address and netmask
`CORP(config-subif)# interface fastethernet 0/0.20`	Creates a virtual subinterface and moves to subinterface configuration mode
`CORP(config-subif)# description Engineering VLAN 20`	Sets the locally significant interface description
`CORP(config-subif)# encapsulation dot1q 20`	Assigns VLAN 20 to this subinterface. This subinterface uses the 802.1q protocol
`CORP(config-subif)# ip address 192.168.20.1 255.255.255.0`	Assigns an IP address and netmask
`CORP(config-subif)# interface fastethernet 0/0.30`	Creates a virtual subinterface and moves to subinterface configuration mode
`CORP(config-subif)# description Marketing VLAN 30`	Sets the locally significant interface description
`CORP(config-subif)# encapsulation dot1q 30`	Assigns VLAN 30 to this subinterface. This subinterface uses the 802.1q protocol
`CORP(config-subif)# ip add 192.168.30.1 255.255.255.0`	Assigns an IP address and netmask
`CORP(config-subif)# exit`	Returns to global configuration mode
`CORP(config)# router eigrp 10`	Creates EIGRP routing process 10 and moves to router configuration mode
`CORP(config-router)# network 192.168.1.0 0.0.0.255`	Advertises the 192.168.1.0 network
`CORP(config-router)# network 192.168.10.0 0.0.0.255`	Advertises the 192.168.10.0 network
`CORP(config-router)# network 192.168.20.0 0.0.0.255`	Advertises the 192.168.20.0 network
`CORP(config-router)# network 192.168.30.0 0.0.0.255`	Advertises the 192.168.30.0 network
`CORP(config-router)# network 172.31.0.0 0.0.255.255`	Advertises the 172.31.0.0 network
`CORP(config-router)# network 192.31.7.0 0.0.0.3`	Advertises the 192.31.7.0 network
`CORP(config-router)# end`	Returns to privileged EXEC mode
`CORP# copy running-config startup-config`	Saves the configuration in NVRAM

L2Switch2 (Catalyst 2960)

`Switch> enable`	Moves to privileged EXEC mode
`Switch# configure terminal`	Moves to global configuration mode
`Switch(config)# hostname L2Switch2`	Sets the host name
`L2Switch2(config)# no ip domain-lookup`	Turns off DNS resolution
`L2Switch2(config)# vlan 10`	Creates VLAN 10 and enters VLAN configuration mode
`L2Switch2(config-vlan)# name Sales`	Assigns a name to the VLAN
`L2Switch2(config-vlan)# exit`	Returns to global configuration mode
`L2Switch2(config)# vlan 20`	Creates VLAN 20 and enters VLAN configuration mode
`L2Switch2(config-vlan)# name Engineering`	Assigns a name to the VLAN
`L2Switch2(config-vlan)# vlan 30`	Creates VLAN 30 and enters VLAN configuration mode. Note that you do not have to exit back to global configuration mode to execute this command
`L2Switch2(config-vlan)# name Marketing`	Assigns a name to the VLAN
`L2Switch2(config-vlan)# exit`	Returns to global configuration mode
`L2Switch2(config)# interface range fastethernet 0/2 - 4`	Enters interface range configuration mode and allows you to set the same configuration parameters on multiple ports at the same time
`L2Switch2(config-if-range)# switchport mode access`	Sets ports 2–4 as access ports
`L2Switch2(config-if-range)# switchport access vlan 10`	Assigns ports 2–4 to VLAN 10
`L2Switch2(config-if-range)# interface range fastethernet 0/5 - 8`	Enters interface range configuration mode and allows you to set the same configuration parameters on multiple ports at the same time
`L2Switch2(config-if-range)# switchport mode access`	Sets ports 5–8 as access ports
`L2Switch2(config-if-range)# switchport access vlan 20`	Assigns ports 5–8 to VLAN 20
`L2Switch2(config-if-range)# interface range fastethernet 0/9 - 12`	Enters interface range configuration mode and allows you to set the same configuration parameters on multiple ports at the same time
`L2Switch2(config-if-range)# switchport mode access`	Sets ports 9–12 as access ports
`L2Switch2(config-if-range)# switchport access vlan 30`	Assigns ports 9–12 to VLAN 30
`L2Switch2(config-if-range)# exit`	Returns to global configuration mode
`L2Switch2(config)# interface fastethernet 0/1`	Moves to interface configuration mode
`L2Switch2(config)# description Trunk Link to CORP Router`	Sets the locally significant interface description
`L2Switch2(config-if)# switchport mode trunk`	Puts the interface into trunking mode and negotiates to convert the link into a trunk link
`L2Switch2(config-if)# exit`	Returns to global configuration mode
`L2Switch2(config)# interface vlan 1`	Creates a virtual interface for VLAN 1 and enters interface configuration mode
`L2Switch2(config-if)# ip address 192.168.1.2 255.255.255.0`	Assigns an IP address and netmask
`L2Switch2(config-if)# no shutdown`	Enables the interface
`L2Switch2(config-if)# exit`	Returns to global configuration mode
`L2Switch2(config)# ip default-gateway 192.168.1.1`	Assigns a default gateway address
`L2Switch2(config)# exit`	Returns to privileged EXEC mode
`L2Switch2# copy running-config startup-config`	Saves the configuration in NVRAM

L3Switch1 (Catalyst 3650)

`Switch> enable`	Moves to privileged EXEC mode
`Switch# configure terminal`	Moves to global configuration mode
`Switch(config)# hostname L3Switch1`	Sets the host name
`L3Switch1(config)# no ip domain-lookup`	Turns off DNS queries so that spelling mistakes do not slow you down
`L3Switch1(config)# vtp mode server`	Changes the switch to VTP server mode
`L3Switch1(config)# vtp domain testdomain`	Configures the VTP domain name to testdomain
`L3Switch1(config)# vlan 10`	Creates VLAN 10 and enters VLAN configuration mode
`L3Switch1(config-vlan)# name Accounting`	Assigns a name to the VLAN
`L3Switch1(config-vlan)# exit`	Returns to global configuration mode
`L3Switch1(config)# vlan 20`	Creates VLAN 20 and enters VLAN configuration mode
`L3Switch1(config-vlan)# name Marketing`	Assigns a name to the VLAN
`L3Switch1(config-vlan)# exit`	Returns to global configuration mode
`L3Switch1(config)# interface gigabitethernet 1/0/1`	Moves to interface configuration mode
`L3Switch1(config-if)# switchport trunk encapsulation dot1q`	Specifies 802.1Q tagging on the trunk link (only necessary on older model switches like the 3560 and 3750)
`L3Switch1(config-if)# switchport mode trunk`	Puts the interface into trunking mode and negotiates to convert the link into a trunk link
`L3Switch1(config-if)# exit`	Returns to global configuration mode
`L3Switch1(config)# ip routing`	Enables IP routing on this device
`L3Switch1(config)# interface vlan 1`	Creates a virtual interface for VLAN 1 and enters interface configuration mode
`L3Switch1(config-if)# ip address 172.16.1.1 255.255.255.0`	Assigns an IP address and netmask
`L3Switch1(config-if)# no shutdown`	Enables the interface
`L3Switch1(config-if)# interface vlan 10`	Creates a virtual interface for VLAN 10 and enters interface configuration mode
`L3Switch1(config-if)# ip address 172.16.10.1 255.255.255.0`	Assigns an IP address and mask
`L3Switch1(config-if)# no shutdown`	Enables the interface
`L3Switch1(config-if)# interface vlan 20`	Creates a virtual interface for VLAN 20 and enters interface configuration mode
`L3Switch1(config-if)# ip address 172.16.20.1 255.255.255.0`	Assigns an IP address and mask
`L3Switch1(config-if)# no shutdown`	Enables the interface
`L3Switch1(config-if)# exit`	Returns to global configuration mode
`L3Switch1(config)# interface gigabitethernet 1/0/24`	Enters interface configuration mode
`L3Switch1(config-if)# no switchport`	Creates a Layer 3 port on the switch
`L3Switch1(config-if)# ip address 172.31.1.6 255.255.255.252`	Assigns an IP address and netmask
`L3Switch1(config-if)# exit`	Returns to global configuration mode
`L3Switch1(config)# router eigrp 10`	Creates EIGRP routing process 10 and moves to router configuration mode
`L3Switch1(config-router)# network 172.16.0.0 0.0.255.255`	Advertises the 172.16.0.0 network
`L3Switch1(config-router)# network 172.31.0.0 0.0.255.255`	Advertises the 172.31.0.0 network
`L3Switch1(config-router)# end`	Applies changes and returns to privileged EXEC mode
`L3Switch1# copy running-config startup-config`	Saves configuration in NVRAM

L2Switch1 (Catalyst 2960)

`Switch> enable`	Moves to privileged EXEC mode
`Switch# configure terminal`	Moves to global configuration mode
`Switch(config)# hostname L2Switch1`	Sets the host name
`L2Switch1(config)# no ip domain-lookup`	Turns off DNS queries so that spelling mistakes do not slow you down
`L2Switch1(config)# vtp domain testdomain`	Configures the VTP domain name to testdomain
`L2Switch1(config)# vtp mode client`	Changes the switch to VTP client mode
`L2Switch1(config)# interface range fastethernet 0/1 - 4`	Enters interface range configuration mode and allows you to set the same configuration parameters on multiple ports at the same time
`L2Switch1(config-if-range)# switchport mode access`	Sets ports 1–4 as access ports
`L2Switch1(config-if-range)# switchport access vlan 10`	Assigns ports 1–4 to VLAN 10
`L2Switch1(config-if-range)# interface range fastethernet 0/5 - 8`	Enters interface range configuration mode and allows you to set the same configuration parameters on multiple ports at the same time
`L2Switch1(config-if-range)# switchport mode access`	Sets ports 5–8 as access ports
`L2Switch1(config-if-range)# switchport access vlan 20`	Assigns ports 5–8 to VLAN 20
`L2Switch1(config-if-range)# exit`	Returns to global configuration mode
`L2Switch1(config)# interface gigabitethernet 0/1`	Moves to interface configuration mode
`L2Switch1(config-if)# switchport mode trunk`	Puts the interface into trunking mode and negotiates to convert the link into a trunk link
`L2Switch1(config-if)# exit`	Returns to global configuration mode
`L2Switch1(config)# interface vlan 1`	Creates a virtual interface for VLAN 1 and enters interface configuration mode
`L2Switch1(config-if)# ip address 172.16.1.2 255.255.255.0`	Assigns an IP address and netmask
`L2Switch1(config-if)# no shutdown`	Enables the interface
`L2Switch1(config-if)# exit`	Returns to global configuration mode
`L2Switch1(config)# ip default-gateway 172.16.1.1`	Assigns the default gateway address
`L2Switch1(config)# exit`	Returns to privileged EXEC mode
`L2Switch1# copy running-config startup-config`	Saves the configuration in NVRAM

5. Configuration Example: IPv6 Inter-VLAN Communication | Next Section Previous Section

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