Lab 15: IPv6 and static routes

Scenario

The network is moving to IPv6. R2 is already configured, except for its route to PC1's LAN. R1 has no IPv6 at all.

On R1, enable IPv6 routing, put 2001:DB8:1::1/64 on G0/0 with link-local FE80::1 (PC1's default gateway) and 2001:DB8:12::1/64 on G0/1. Create an IPv6 default route via 2001:DB8:12::2. On R2, add the route to 2001:DB8:1::/64 via 2001:DB8:12::1.

Check it with ping 2001:DB8:2::10 from PC1.

Topology

Devices and cabling

R1, R2 · 2911
PC1, PC2 · PC-PT

From	To	Cable
PC1 Fa0	R1 Gi0/0	Crossover
R1 Gi0/1	R2 Gi0/0	Crossover
R2 Gi0/1	PC2 Fa0	Crossover

If in doubt, the automatic connection cable (the lightning bolt) picks the right one. Rule: straight-through between different devices (PC or router to switch) and crossover between alike ones.

Addressing

Device	Interface	Address	Mask	Default gateway
R1	G0/0	2001:DB8:1::1 · FE80::1	/64	—
R1	G0/1	2001:DB8:12::1	/64	—
R2	G0/0	2001:DB8:12::2	/64	—
R2	G0/1	2001:DB8:2::1 · FE80::2	/64	—
PC1	NIC	2001:DB8:1::10	/64	FE80::1
PC2	NIC	2001:DB8:2::10	/64	FE80::2

Starting configuration

In the app this is already done. In Packet Tracer, before you start, enter each device with enable and configure terminal and type (or paste) these lines.

R1hostname R1 no ip domain-lookup interface g0/0 no shutdown interface g0/1 no shutdown

R2hostname R2 no ip domain-lookup ipv6 unicast-routing interface g0/0 ipv6 address 2001:db8:12::2/64 no shutdown interface g0/1 ipv6 address 2001:db8:2::1/64 ipv6 address fe80::2 link-local no shutdown

PCs and servers (Desktop › IP Configuration)

PC1: IPv6 2001:DB8:1::10/64, gateway FE80::1
PC2: IPv6 2001:DB8:2::10/64, gateway FE80::2

Tasks

What must end up working. In the app, each one ticks itself off as soon as you get it.

R1 routes IPv6
G0/0: 2001:DB8:1::1/64 and link-local FE80::1
G0/1: 2001:DB8:12::1/64
R1: default route ::/0 via 2001:DB8:12::2
R2: route to 2001:DB8:1::/64 via 2001:DB8:12::1
PC1 reaches PC2 over IPv6
Checked with show ipv6 route

In Packet Tracer

Each PC's IPv6 address is set in Desktop › IP Configuration, in the IPv6 section (Static).
In the starting configuration, R1 only brings its interfaces up; R2 already has its IPv6.

Hints

R1 routes IPv6: ipv6 unicast-routing (without it the router won't forward IPv6)
G0/0: 2001:DB8:1::1/64 and link-local FE80::1: ipv6 address 2001:db8:1::1/64 and ipv6 address fe80::1 link-local
G0/1: 2001:DB8:12::1/64: interface g0/1 → ipv6 address 2001:db8:12::1/64
R1: default route ::/0 via 2001:DB8:12::2: ipv6 route ::/0 2001:db8:12::2
R2: route to 2001:DB8:1::/64 via 2001:DB8:12::1: ipv6 route 2001:db8:1::/64 2001:db8:12::1
PC1 reaches PC2 over IPv6: From PC1: ping 2001:db8:2::10
Checked with show ipv6 route: show ipv6 route on R1

Step-by-step solution

Try it on your own first: you learn much more by typing the commands yourself.

Show the solution

1Enable IPv6 routing R1

Without ipv6 unicast-routing the router has IPv6 addresses but doesn't forward packets.

R1enable configure terminal ipv6 unicast-routing

2G0/0 addresses R1

The FE80::1 link-local is what PC1 uses as its default gateway: setting it by hand makes it easy to remember.

R1interface g0/0 ipv6 address 2001:db8:1::1/64 ipv6 address fe80::1 link-local

3G0/1 address R1

R1interface g0/1 ipv6 address 2001:db8:12::1/64 exit

4IPv6 default route R1

::/0 is the IPv6 equivalent of 0.0.0.0/0.

R1ipv6 route ::/0 2001:db8:12::2 end

5Return route on R2 R2

R2enable configure terminal ipv6 route 2001:db8:1::/64 2001:db8:12::1 end

Verification

The connected networks (C), the router's own addresses (L) and the default route (S ::/0).

R1R1#show ipv6 route IPv6 Routing Table - default - 6 entries Codes: C - Connected, L - Local, S - Static, U - Per-user Static route B - BGP, R - RIP, I1 - ISIS L1, I2 - ISIS L2 IA - ISIS interarea, IS - ISIS summary, D - EIGRP, EX - EIGRP external ND - ND Default, NDp - ND Prefix, DCE - Destination, NDr - Redirect O - OSPF Intra, OI - OSPF Inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2 ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2 S ::/0 [1/0] via 2001:DB8:12::2 C 2001:DB8:1::/64 [0/0] via GigabitEthernet0/0, directly connected L 2001:DB8:1::1/128 [0/0] via GigabitEthernet0/0, receive C 2001:DB8:12::/64 [0/0] via GigabitEthernet0/1, directly connected L 2001:DB8:12::1/128 [0/0] via GigabitEthernet0/1, receive L FF00::/8 [0/0] via Null0, receive

PC1 reaches PC2 over IPv6 across both routers.

PC1C:\>ping 2001:db8:2::10 Pinging 2001:DB8:2::10 with 32 bytes of data: Reply from 2001:DB8:2::10: bytes=32 time<1ms TTL=126 Reply from 2001:DB8:2::10: bytes=32 time<1ms TTL=126 Reply from 2001:DB8:2::10: bytes=32 time<1ms TTL=126 Reply from 2001:DB8:2::10: bytes=32 time<1ms TTL=126 Ping statistics for 2001:DB8:2::10: Packets: Sent = 4, Received = 4, Lost = 0 (0% loss), Approximate round trip times in milli-seconds: Minimum = 0ms, Maximum = 0ms, Average = 0ms

Common mistakes

Forgetting ipv6 unicast-routing: everything looks fine, but the router doesn't forward.
Using a link-local as the next hop without specifying the exit interface.

Practice this lab on your phone

RoutingLab has this lab with a simulated IOS terminal: abbreviations, ? help, the same error messages and objectives that check themselves. The first two labs are free.

Get RoutingLab

← PreviousPort security