Lab Objective
Configure a default IPv6 static route on an edge router pointing toward an ISP, verify it appears as the gateway of last resort, and confirm it successfully routes traffic to a destination with no more specific matching route.
Lab Purpose
Just as with IPv4, discussed in an earlier lab, maintaining individual IPv6 routes for every possible internet destination is impractical. The IPv6 default route uses different notation from its IPv4 counterpart but serves the identical purpose.
Lab Topology
R1 (edge router) ---- Serial0/0/1 ---- ISP Router
R1's internal LAN: 2001:DB8:D:1::/64
R1's serial address: 2001:DB8:FFFF:1::1/64
ISP's serial address: 2001:DB8:FFFF:1::2/64Task 1: Configure Basic IPv6 Addressing
Configure R1's serial interface toward the ISP and its internal LAN interface.
Task 2: Configure the Default IPv6 Static Route
Configure a default route on R1 pointing to the ISP's serial address.
Task 3: Verify the Gateway of Last Resort
Confirm the IPv6 routing table identifies this route as the gateway of last resort.
Task 4: Test the Default Route
Ping an IPv6 address with no specific matching route in R1's table and confirm the default route is used.
Solution and Verification
R1(config)# ipv6 unicast-routing
R1(config)# interface serial0/0/1
R1(config-if)# ipv6 address 2001:DB8:FFFF:1::1/64
R1(config-if)# no shutdown
R1(config-if)# exit
R1(config)# interface gigabitethernet0/0
R1(config-if)# ipv6 address 2001:DB8:D:1::1/64
R1(config-if)# no shutdownR1(config)# ipv6 route ::/0 2001:DB8:FFFF:1::2
-- ::/0 is the IPv6 equivalent of IPv4's
-- 0.0.0.0/0 -- a prefix length of 0 means
-- no bits need to match, so every possible
-- destination is coveredR1# show ipv6 route
IPv6 Routing Table
S ::/0 [1/0]
via 2001:DB8:FFFF:1::2
C 2001:DB8:D:1::/64 [0/0]
via GigabitEthernet0/0, directly connected
C 2001:DB8:FFFF:1::/64 [0/0]
via Serial0/0/1, directly connectedR1# ping 2001:4860:4860::8888
-- (simulated public IPv6 destination beyond
-- the ISP, no specific route exists for it)
!!!!!
Success rate is 100 percent (5/5)
R1# show ipv6 route 2001:4860:4860::8888
% Route not found
-- Confirms no specific entry exists, yet the
-- ping succeeded because the default route
-- (::/0) caught it insteadKey Takeaway
::/0 is IPv6's notation for "match everything," functionally identical to IPv4's 0.0.0.0/0 covered in an earlier lab — the underlying concept of a default route catching any destination without a more specific match carries over completely between the two protocols, only the address notation itself differs.