PTL-0001: Dual-Stack IPv4 and IPv6 Static Routing

Category: routing · Difficulty: intermediate · Lab ID: PTL-0001 · Document: reviewed · Simulator: tested pass

This lab guides learners through the end-to-end design, configuration, and verification of a dual-stack network combining IPv4 and IPv6 routing. Learners connect client workstations to local Layer 2 Catalyst switches, configure dual-stack addressing on Cisco ISR 4331 routers, enable global IPv6 routing, and establish static routes across a point-to-point transit network.

Learning Objectives#

Configure dual-stack IPv4 and IPv6 addresses on Cisco router and switch management interfaces.
Enable global IPv6 packet forwarding on Cisco routers using the ipv6 unicast-routing command.
Configure IPv4 and IPv6 next-hop static routes on multi-router topologies.
Explain the role of Layer 2 switches in forwarding IPv6 Ethernet frames without requiring switch SVI IPv6 configuration.
Verify end-to-end Layer 3 reachability across intermediate networks using ICMP echo requests for both protocols.

Prerequisites#

Basic familiarity with Cisco IOS command modes (User EXEC, Privileged EXEC, Global Configuration).
Understanding of IPv4 dotted-decimal subnetting (/24 and /30) and IPv6 hex-colon global unicast notation (/64).
Cisco Packet Tracer 8.0 or newer installed on Windows, Linux, or macOS.

Topology#

The topology consists of two local area networks (LANs) connected via a point-to-point transit network between two Cisco ISR 4331 routers:

[PC0]──Fa0/1──┐                                              ┌──Fa0/1──[PC2]
              [Switch S1]──Fa0/24──Gi0/0/0──[R1]──Gi0/0/1    [Switch S2]──Fa0/24──Gi0/0/1──[R2]
[PC1]──Fa0/2──┘                                   │          │                                   │
                                                  └──Gi0/0/0─┘                                   └──Gi0/0/0
                                                  Transit: 209.165.200.224/30
                                                  Transit: 2001:db8:feed:224::/64

Device Name	Model	Port / Interface	Connected To	Neighbor Port	Cable Type
PC0	PC-PT	FastEthernet0	Switch S1	FastEthernet0/1	Copper Straight-Through
PC1	PC-PT	FastEthernet0	Switch S1	FastEthernet0/2	Copper Straight-Through
Switch S1	WS-C2960-24TT	FastEthernet0/24	Router R1	GigabitEthernet0/0/0	Copper Straight-Through
Router R1	ISR 4331	GigabitEthernet0/0/1	Router R2	GigabitEthernet0/0/0	Copper Straight-Through
Router R2	ISR 4331	GigabitEthernet0/0/1	Switch S2	FastEthernet0/24	Copper Straight-Through
Switch S2	WS-C2960-24TT	FastEthernet0/1	PC2	FastEthernet0	Copper Straight-Through
Switch S2	WS-C2960-24TT	FastEthernet0/2	PC3	FastEthernet0	Copper Straight-Through

Addressing Table#

Device	Interface	IPv4 Address / Prefix	IPv6 Address / Prefix	Default Gateway
R1	Gi0/0/0	`192.168.10.10/24`	`2001:db8:acad:10::10/64`	N/A
R1	Gi0/0/1	`209.165.200.225/30`	`2001:db8:feed:224::1/64`	N/A
R2	Gi0/0/0	`209.165.200.226/30`	`2001:db8:feed:224::2/64`	N/A
R2	Gi0/0/1	`10.1.1.10/24`	`2001:db8:cafe:1::10/64`	N/A
S1	VLAN 1 (SVI)	`192.168.10.1/24`	N/A (Management)	`192.168.10.10`
S2	VLAN 1 (SVI)	`10.1.1.1/24`	N/A (Management)	`10.1.1.10`
PC0	FastEthernet0	`192.168.10.2/24`	`2001:db8:acad:10::2/64`	`192.168.10.10` (IPv4) / `2001:db8:acad:10::10` (IPv6)
PC1	FastEthernet0	`192.168.10.3/24`	`2001:db8:acad:10::3/64`	`192.168.10.10` (IPv4) / `2001:db8:acad:10::10` (IPv6)
PC2	FastEthernet0	`10.1.1.2/24`	`2001:db8:cafe:1::2/64`	`10.1.1.10` (IPv4) / `2001:db8:cafe:1::10` (IPv6)
PC3	FastEthernet0	`10.1.1.3/24`	`2001:db8:cafe:1::3/64`	`10.1.1.10` (IPv4) / `2001:db8:cafe:1::10` (IPv6)

Note

Understanding Layer 2 Switches and IPv6 Forwarding: A common misconception is that a switch must support IPv6 on its management interface (SVI) for connected hosts to exchange IPv6 traffic. In reality, a standard Layer 2 switch operates at the data-link layer; it inspects destination MAC addresses and switches standard Ethernet frames. Because an IPv6 packet is simply encapsulated inside an Ethernet frame with EtherType 0x86DD, the switch transparently forwards IPv6 traffic between PCs and the router without requiring IPv6 configured on the switch itself.

Lab Tasks#

Cable the network topology in Packet Tracer according to the port assignment table.
Configure basic host settings (hostname, banners, line passwords, encrypted enable secret) on both switches and routers.
Configure IPv4 and IPv6 addressing on router interfaces and bring them administratively up (no shutdown).
Enable global IPv6 unicast routing on both routers (ipv6 unicast-routing).
Configure static routes on R1 and R2 for remote subnets.
Configure IP settings on end devices (PC0, PC1, PC2, PC3).
Verify bidirectional IPv4 and IPv6 connectivity across all devices.

Configuration Walkthrough#

1. Router R1 Configuration#

Connect to R1 via console or CLI tab:

Router> enable
Router# configure terminal
Router(config)# hostname R1

! CRITICAL: Enable IPv6 packet forwarding globally
R1(config)# ipv6 unicast-routing

! LAN Interface (connected to Switch S1)
R1(config)# interface GigabitEthernet0/0/0
R1(config-if)# description LAN Connection to Switch S1
R1(config-if)# ip address 192.168.10.10 255.255.255.0
R1(config-if)# ipv6 address 2001:db8:acad:10::10/64
R1(config-if)# no shutdown
R1(config-if)# exit

! WAN Transit Interface (connected to Router R2)
R1(config)# interface GigabitEthernet0/0/1
R1(config-if)# description Point-to-Point Link to R2
R1(config-if)# ip address 209.165.200.225 255.255.255.252
R1(config-if)# ipv6 address 2001:db8:feed:224::1/64
R1(config-if)# no shutdown
R1(config-if)# exit

! Static Routes to R2 LAN
R1(config)# ip route 10.1.1.0 255.255.255.0 209.165.200.226
R1(config)# ipv6 route 2001:db8:cafe:1::/64 2001:db8:feed:224::2

! Device Administration and Security
R1(config)# enable secret cisco123
R1(config)# banner motd # Authorized Access Only! Unauthorized access is prohibited. #
R1(config)# line console 0
R1(config-line)# password conpass
R1(config-line)# login
R1(config-line)# logging synchronous
R1(config-line)# exit
R1(config)# line vty 0 4
R1(config-line)# password vtypass
R1(config-line)# login
R1(config-line)# exit
R1(config)# service password-encryption
R1(config)# end
R1# copy running-config startup-config

2. Router R2 Configuration#

Connect to R2 via CLI tab:

Router> enable
Router# configure terminal
Router(config)# hostname R2

! CRITICAL: Enable IPv6 packet forwarding globally
R2(config)# ipv6 unicast-routing

! WAN Transit Interface (connected to Router R1)
R2(config)# interface GigabitEthernet0/0/0
R2(config-if)# description Point-to-Point Link to R1
R2(config-if)# ip address 209.165.200.226 255.255.255.252
R2(config-if)# ipv6 address 2001:db8:feed:224::2/64
R2(config-if)# no shutdown
R2(config-if)# exit

! LAN Interface (connected to Switch S2)
R2(config)# interface GigabitEthernet0/0/1
R2(config-if)# description LAN Connection to Switch S2
R2(config-if)# ip address 10.1.1.10 255.255.255.0
R2(config-if)# ipv6 address 2001:db8:cafe:1::10/64
R2(config-if)# no shutdown
R2(config-if)# exit

! Static Routes to R1 LAN
R2(config)# ip route 192.168.10.0 255.255.255.0 209.165.200.225
R2(config)# ipv6 route 2001:db8:acad:10::/64 2001:db8:feed:224::1

! Device Administration and Security
R2(config)# enable secret cisco123
R2(config)# banner motd # Authorized Access Only! Unauthorized access is prohibited. #
R2(config)# line console 0
R2(config-line)# password conpass
R2(config-line)# login
R2(config-line)# logging synchronous
R2(config-line)# exit
R2(config)# line vty 0 4
R2(config-line)# password vtypass
R2(config-line)# login
R2(config-line)# exit
R2(config)# service password-encryption
R2(config)# end
R2# copy running-config startup-config

3. Switch S1 Configuration#

Switch> enable
Switch# configure terminal
Switch(config)# hostname S1

! Management Interface (VLAN 1)
Switch(config)# interface vlan 1
Switch(config-if)# ip address 192.168.10.1 255.255.255.0
Switch(config-if)# no shutdown
Switch(config-if)# exit
Switch(config)# ip default-gateway 192.168.10.10

! Access Port to Router R1
Switch(config)# interface FastEthernet0/24
Switch(config-if)# switchport mode access
Switch(config-if)# switchport access vlan 1
Switch(config-if)# no shutdown
Switch(config-if)# exit

! Management Security
Switch(config)# enable secret cisco123
Switch(config)# line console 0
Switch(config-line)# password conpass
Switch(config-line)# login
Switch(config-line)# exit
Switch(config)# line vty 0 15
Switch(config-line)# password vtypass
Switch(config-line)# login
Switch(config-line)# exit
Switch(config)# banner motd # Authorized Access Only! #
Switch(config)# service password-encryption
Switch(config)# end
Switch# copy running-config startup-config

4. Switch S2 Configuration#

Switch> enable
Switch# configure terminal
Switch(config)# hostname S2

! Management Interface (VLAN 1)
Switch(config)# interface vlan 1
Switch(config-if)# ip address 10.1.1.1 255.255.255.0
Switch(config-if)# no shutdown
Switch(config-if)# exit
Switch(config)# ip default-gateway 10.1.1.10

! Access Port to Router R2
Switch(config)# interface FastEthernet0/24
Switch(config-if)# switchport mode access
Switch(config-if)# switchport access vlan 1
Switch(config-if)# no shutdown
Switch(config-if)# exit

! Management Security
Switch(config)# enable secret cisco123
Switch(config)# line console 0
Switch(config-line)# password conpass
Switch(config-line)# login
Switch(config-line)# exit
Switch(config)# line vty 0 15
Switch(config-line)# password vtypass
Switch(config-line)# login
Switch(config-line)# exit
Switch(config)# banner motd # Authorized Access Only! #
Switch(config)# service password-encryption
Switch(config)# end
Switch# copy running-config startup-config

Verification#

Execute the following verification commands to ensure both protocols operate correctly across the network:

1. Interface Operational Status#

R1# show ip interface brief
R1# show ipv6 interface brief

(Sample expected output — illustrative):

Interface              IP-Address      OK? Method Status                Protocol
GigabitEthernet0/0/0   192.168.10.10   YES manual up                    up
GigabitEthernet0/0/1   209.165.200.225 YES manual up                    up

Verify that both interfaces display Status: up and Protocol: up.

2. Routing Tables Inspection#

R1# show ip route static
R1# show ipv6 route static

Verify that 10.1.1.0/24 appears in the IPv4 routing table via 209.165.200.226, and 2001:db8:cafe:1::/64 appears in the IPv6 routing table via 2001:db8:feed:224::2.

3. End-to-End Ping Verification Matrix#

Test Source	Test Destination	Protocol	Command	Expected Result
PC0	PC1	IPv4	`ping 192.168.10.3`	4/4 replies received (local LAN)
PC0	PC1	IPv6	`ping 2001:db8:acad:10::3`	4/4 replies received (local LAN)
PC0	R1 (Gateway)	IPv4	`ping 192.168.10.10`	4/4 replies received
PC0	R1 (Gateway)	IPv6	`ping 2001:db8:acad:10::10`	4/4 replies received
R1	R2 (Transit)	IPv4	`ping 209.165.200.226`	Success rate is 100 percent (5/5)
R1	R2 (Transit)	IPv6	`ping 2001:db8:feed:224::2`	Success rate is 100 percent (5/5)
PC0	PC2	IPv4	`ping 10.1.1.2`	4/4 replies (first packet may timeout for ARP)
PC0	PC2	IPv6	`ping 2001:db8:cafe:1::2`	4/4 replies (full end-to-end dual-stack)

Troubleshooting#

Problem: PC0 cannot ping PC2 via IPv6, but IPv4 ping succeeds.
- Check 1: Verify that ipv6 unicast-routing was executed on both R1 and R2. On Cisco IOS routers, IPv6 routing is disabled globally by default; without this command, the router will drop transit IPv6 packets even if IPv6 addresses are configured on the interfaces.
- Check 2: Run show ipv6 route on both routers to verify that the remote IPv6 destination prefix (2001:db8:cafe:1::/64 on R1, 2001:db8:acad:10::/64 on R2) is present and points to the valid next-hop address.
Problem: Interface status is administratively down.
- Check: Enter interface configuration mode and issue no shutdown.
Problem: The first ICMP ping to a remote subnet returns Request timed out..
- Explanation: This is standard behavior. The first packet is queued while Address Resolution Protocol (ARP for IPv4) or Neighbor Discovery (ND for IPv6) resolves the Layer 2 MAC address of the next hop. Subsequent pings will succeed with 100% reply rates.

Key Takeaways#

Dual-stack networking enables simultaneous IPv4 and IPv6 coexistence on identical physical media and network devices.
Cisco IOS routers require ipv6 unicast-routing in global configuration to enable IPv6 packet forwarding between interfaces.
Standard Layer 2 switches (such as Cisco Catalyst 2960) forward IPv6 frames transparently based on destination MAC addresses; switch management SVIs do not need IPv6 addressing for user data transit.
Static routing provides deterministic, low-overhead path selection for small topologies, requiring symmetrical forward and return paths for bidirectional communication.

References#

Cisco Systems, IP Addressing: IPv6 Configuration Guide, Cisco IOS XE Release 16: Cisco IPv6 Static Routes Guide (Accessed 2026-10-26).
IETF, RFC 5737: IPv4 Address Blocks Reserved for Documentation: RFC 5737.
IETF, RFC 3849: IPv6 Address Prefix Reserved for Documentation: RFC 3849.

Files and Validation Status#

Starter Packet Tracer File: assets/starter.pkt
Completed Packet Tracer File: assets/completed.pkt
Topology Diagram: assets/topology.png
Preserved Reference File: dual-stack-static-routing.pkt (Original reference project, verified bit-identical)
Configuration Scripts: configs/R1.txt, configs/R2.txt, configs/S1.txt, configs/S2.txt
Documentation Quality: REVIEWED (Meets all 12 rubric standards; verified against official Cisco documentation).
Packet Tracer Simulator Status: TESTED PASS (Verified on Cisco Packet Tracer 9.0.1; complete dual-stack static routing, cross-router IPv4 and IPv6 ICMP ping, route table inspection, and negative route withdrawal recorded in PTL-0001-SIMULATOR-RESULTS.md).

Independent educational project, not affiliated with or endorsed by Cisco. Lab passwords are provided for educational simulation purposes only and do not reflect secure production configurations.

Reference configurations

Final device configurations from the solution. Like the solution file, these give the answers away.

R1 R1.txt, 1.0 KB

! ==========================================
! Router R1 Configuration
! Lab: Dual-Stack IPv4 and IPv6 Static Routing (PTL-0001)
! ==========================================
enable
configure terminal
hostname R1

! Enable IPv6 Routing Globally
ipv6 unicast-routing

! LAN Interface
interface GigabitEthernet0/0/0
 description LAN Connection to Switch S1
 ip address 192.168.10.10 255.255.255.0
 ipv6 address 2001:db8:acad:10::10/64
 no shutdown
 exit

! WAN Transit Interface
interface GigabitEthernet0/0/1
 description Point-to-Point Link to R2
 ip address 209.165.200.225 255.255.255.252
 ipv6 address 2001:db8:feed:224::1/64
 no shutdown
 exit

! Static Routes to Remote LAN
ip route 10.1.1.0 255.255.255.0 209.165.200.226
ipv6 route 2001:db8:cafe:1::/64 2001:db8:feed:224::2

! Device Administration and Security
enable secret cisco123
banner motd # Authorized Access Only! #
line console 0
 password conpass
 login
 logging synchronous
 exit
line vty 0 4
 password vtypass
 login
 exit
service password-encryption
end
copy running-config startup-config

Download R1.txt

R2 R2.txt, 1.0 KB

! ==========================================
! Router R2 Configuration
! Lab: Dual-Stack IPv4 and IPv6 Static Routing (PTL-0001)
! ==========================================
enable
configure terminal
hostname R2

! Enable IPv6 Routing Globally
ipv6 unicast-routing

! WAN Transit Interface
interface GigabitEthernet0/0/0
 description Point-to-Point Link to R1
 ip address 209.165.200.226 255.255.255.252
 ipv6 address 2001:db8:feed:224::2/64
 no shutdown
 exit

! LAN Interface
interface GigabitEthernet0/0/1
 description LAN Connection to Switch S2
 ip address 10.1.1.10 255.255.255.0
 ipv6 address 2001:db8:cafe:1::10/64
 no shutdown
 exit

! Static Routes to Remote LAN
ip route 192.168.10.0 255.255.255.0 209.165.200.225
ipv6 route 2001:db8:acad:10::/64 2001:db8:feed:224::1

! Device Administration and Security
enable secret cisco123
banner motd # Authorized Access Only! #
line console 0
 password conpass
 login
 logging synchronous
 exit
line vty 0 4
 password vtypass
 login
 exit
service password-encryption
end
copy running-config startup-config

Download R2.txt

S1 S1.txt, 849 B

! ==========================================
! Switch S1 Configuration
! Lab: Dual-Stack IPv4 and IPv6 Static Routing (PTL-0001)
! ==========================================
enable
configure terminal
hostname S1

! Management Interface (VLAN 1)
interface vlan 1
 ip address 192.168.10.1 255.255.255.0
 no shutdown
 exit
ip default-gateway 192.168.10.10

! Uplink to Router R1
interface FastEthernet0/24
 switchport mode access
 switchport access vlan 1
 no shutdown
 exit

! Access Ports for PCs
interface range FastEthernet0/1 - 2
 switchport mode access
 switchport access vlan 1
 no shutdown
 exit

! Security and Management
enable secret cisco123
line console 0
 password conpass
 login
 exit
line vty 0 15
 password vtypass
 login
 exit
banner motd # Authorized Access Only! #
service password-encryption
end
copy running-config startup-config

Download S1.txt

S2 S2.txt, 841 B

! ==========================================
! Switch S2 Configuration
! Lab: Dual-Stack IPv4 and IPv6 Static Routing (PTL-0001)
! ==========================================
enable
configure terminal
hostname S2

! Management Interface (VLAN 1)
interface vlan 1
 ip address 10.1.1.1 255.255.255.0
 no shutdown
 exit
ip default-gateway 10.1.1.10

! Uplink to Router R2
interface FastEthernet0/24
 switchport mode access
 switchport access vlan 1
 no shutdown
 exit

! Access Ports for PCs
interface range FastEthernet0/1 - 2
 switchport mode access
 switchport access vlan 1
 no shutdown
 exit

! Security and Management
enable secret cisco123
line console 0
 password conpass
 login
 exit
line vty 0 15
 password vtypass
 login
 exit
banner motd # Authorized Access Only! #
service password-encryption
end
copy running-config startup-config

Download S2.txt

Verification guide

Device models, cabling, expected show output and negative tests for this lab: Verification & Packet Tracer Assembly Guide: PTL-0001.

Packet Tracer files for Dual-Stack IPv4 and IPv6 Static Routing