1. 11: IPv6 Routing Table and Static Routes
Rick Graziani
Cabrillo College

2. For more information please check out my Cisco Press book and video series:
IPv6 Fundamentals: A Straightforward Approach to Understanding IPv6
By Rick Graziani
ISBN-10:
IPv6 Fundamentals LiveLessons: A Straightforward Approach to Understanding IPv6
By Rick Graziani
ISBN-10:

3. 11.1: Enabling the IPv6 Router

4. Routers versus IPv6 Routers ICMPv6 Router Advertisement
Router(config)# ipv6 unicast-routing
2001:DB8:CAFE:1::1/64
FE80::1
2001:DB8:CAFE:1::1/64
FE80::1
Router
FF02::1 (All-IPv6 devices)
IPv6 Router
FF02::1 (All-IPv6 devices)
FF02::2 (All-IPv6 routers)
ICMPv6 Router Advertisement
A router (not enabled as an IPv6 router):
Configure IPv6 addresses
Member of All-IPv6 devices multicast group
An IPv6 router:
Same as a non-IPv6 router
Member of All-IPv6 routers multicast group
Sends ICMPv6 Router Advertisement messages
Can enable IPv6 routing protocols
Forward IPv6 packets (transiting the router)
RIPng OSPFv3
EIGRP for IPv6
Forward IPv6 Packets
Documentation states that only an IPv6 router can forward IPv6 packets, however IOS does allow you to configure IPv6 static routes and it forwards IPv6 packets using those routes.

5. Non-IPv6 Enabled Router
R1(config)# interface gigabitEthernet 0/0
R1(config-if)# ipv6 address 2001:db8:cafe:1::1/64
R1(config-if)# ipv6 address fe80::1 link-local
R1(config-if)# no shutdown
R1(config-if)# exit
R1(config)# ipv6 router eigrp 1
% IPv6 routing not enabled
R1(config)# R1
Unlike IPv4, a router must be configured to be an “IPv6 router”.
You can configure IPv6 addresses, but not IPv6 routing protocols.

6. Non-IPv6 Enabled Router
R1# show ipv6 interface gig 0/0
GigabitEthernet0/0 is up, line protocol is up
IPv6 is enabled, link-local address is FE80::1
No Virtual link-local address(es):
Global unicast address(es):
2001:DB8:CAFE:1::1, subnet is 2001:DB8:CAFE:1::/64
Joined group address(es):
FF02::1
FF02::1:FF00:1
<output to be continued>
Member of these Multicast Groups
All-IPv6 devices on this link
Solicited-node multicast addresses
(GUA and link-local)
No FF02::2 All-IPv6 routers
IPv6 Routers are part of the All-IPv6 routers multicast group (FF02::2)

7. Non-IPv6 Enabled Router
R1# show ipv6 interface gig 0/0
<output continued>
MTU is 1500 bytes
ICMP error messages limited to one every 100 milliseconds
ICMP redirects are enabled
ICMP unreachables are sent
ND DAD is enabled, number of DAD attempts: 1
ND reachable time is milliseconds (using 30000)
ND NS retransmit interval is 1000 milliseconds
R1#
No “ND router advertisements”
IPv6 Routers send ICMPv6 Router Advertisement messages out its interfaces

8. ip unicast-routing Command: IPv6 Router
R1(config)# ipv6 unicast-routing
R1(config)# exit
R1# show ipv6 interface gig 0/0
GigabitEthernet0/0 is up, line protocol is up
IPv6 is enabled, link-local address is FE80::1
No Virtual link-local address(es):
Global unicast address(es):
2001:DB8:CAFE:1::1, subnet is 2001:DB8:CAFE:1::/64
Joined group address(es):
FF02::1
FF02::2
FF02::1:FF00:1
<output to be continued>
Member of these Multicast Groups
All-IPv6 routers
ICMPv6
Similar to “old” ip routing command for IPv4 which is enabled by default

9. IPv6 Enabled Router ICMPv6
R1# show ipv6 interface gig 0/0
<output continued>
ICMP error messages limited to one every 100 milliseconds
ICMP redirects are enabled
ICMP unreachables are sent
ND DAD is enabled, number of DAD attempts: 1
ND reachable time is milliseconds (using 30000)
ND advertised reachable time is 0 (unspecified)
ND advertised retransmit interval is 0 (unspecified)
ND router advertisements are sent every 200 seconds
ND router advertisements live for 1800 seconds
ND advertised default router preference is Medium
Hosts use stateless autoconfig for addresses.
R1#
Sending ICMPv6 Router Advertisement Messages
Default: SLAAC
ICMPv6

10. IPv6 Enabled Router IPv6 routing protocols can now be configured!
R1(config)# ipv6 router eigrp 1
R1(config-rtr)#
IPv6 routing protocols can now be configured!
No error message

11. 11.2: IPv6 Routing Table

12. IPv6 Routing Table ICMPv6 2001:DB8:CAFE:1::/64 Gig 0/0 :1 R1
R1# 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, a – Application
C :DB8:CAFE:1::/64 [0/0]
via GigabitEthernet0/0, directly connected
L :DB8:CAFE:1::1/128 [0/0]
via GigabitEthernet0/0, receive
L FF00::/8 [0/0]
via Null0, receive
R1#
Gig 0/0 :1
2001:DB8:CAFE:1::/64
ICMPv6 R1

13. Connected Routes ICMPv6 2001:DB8:CAFE:1::/64 Gig 0/0 :1 R1
R1# 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, a – Application
C :DB8:CAFE:1::/64 [0/0]
via GigabitEthernet0/0, directly connected
L :DB8:CAFE:1::1/128 [0/0]
via GigabitEthernet0/0, receive
L FF00::/8 [0/0]
via Null0, receive
R1#
[Administrative Distance/Metric]
Gig 0/0 :1
2001:DB8:CAFE:1::/64
ICMPv6
Similar to IPv4
Admin distance for directly conn routeis always 0 – can’t be changed
Only directly connected routes can have a admin dist of 0 – static routes with exit interfaces cannot (misconceptio) R1

14. Local Routes
R1# 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, a – Application
C :DB8:CAFE:1::/64 [0/0]
via GigabitEthernet0/0, directly connected
L :DB8:CAFE:1::1/128 [0/0]
via GigabitEthernet0/0, receive
L FF00::/8 [0/0]
via Null0, receive
R1#
Local routes are /128 routes (host routes) for the router’s IPv6 unicast addresses.
Allows the router to more efficiently process packets directed to the router itself rather than for packet forwarding.
Gig 0/0 :1
2001:DB8:CAFE:1::/64
ICMPv6
Local routes are NOT link-local routes R1

15. FF00::/8 to Null0
R1# 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, a – Application
C :DB8:CAFE:1::/64 [0/0]
via GigabitEthernet0/0, directly connected
L :DB8:CAFE:1::1/128 [0/0]
via GigabitEthernet0/0, receive
L FF00::/8 [0/0]
via Null0, receive
R1#
By default multicast packets (FF00::/8) are not forwarded.
Any ‘more specific’ multicast packets (such as FF05::1:3 All-DHCPv6 servers) would take precedence.
ipv6 multicast-routing would need to be configured
Link-local multicast (FF02) are never forwarded off the link.
Gig 0/0 :1
2001:DB8:CAFE:1::/64
ICMPv6 R1 R1

16. 11.3: IPv6 Static Routes and CEF

17. Simplified IPv6 Static Route Configuration
Router(config)# ipv6 route ipv6-prefix/prefix-length {exit-intf | ipv6-address}
Parameter
Description
ipv6-prefix
Destination IPv6 network address of the remote network to be added to the routing table.
/prefix-length
Prefix-length of the remote network or summarized group networks to be added to the routing table.
exit-intf
Use the outgoing interface to forward packets to the destination network.
ipv6-address
Commonly referred to as the next-hop router’s IPv6 address.
Similar to configuring static routes in IPv4.
The more complete syntax is similar to that for IPv4
For the purposes of this section, assume that you are familiar with configuring IPv4 static routes.

18. Configuring IPv6 Static Route
2001:DB8:CAFE:1::/64
2001:DB8:CAFE:2::/64
2001:DB8:FEED:1::/64
2001:DB8:FEED:2::/64
2001:DB8:FEED:3::/64
2001:DB8:FEED:4::/64
2001:DB8:FEED:5::/64
S0/0/0 :2
G0/0 :1
S0/0/0 :1 R1 R2
Static Route
R2(config)# ipv6 unicast-routing
R2(config)# ipv6 route 2001:db8:cafe:1::/ :db8:cafe:2::1

19. Verifying IPv6 Static Route
2001:DB8:CAFE:1::/64
2001:DB8:CAFE:2::/64
2001:DB8:FEED:1::/64
2001:DB8:FEED:2::/64
2001:DB8:FEED:3::/64
2001:DB8:FEED:4::/64
2001:DB8:FEED:5::/64
S0/0/0 :2
G0/0 :1
S0/0/0 :1 R1 R2
Static Route
R2# show ipv6 route static
IPv6 Routing Table - default - 14 entries
Codes: C - Connected, L - Local, S - Static, U - Per-user Static route
<output omitted>
S :DB8:CAFE:1::/64 [1/0]
via 2001:DB8:CAFE:2::1
R2#

20. IPv6 Static Routes R1 R2 Static Routes S0/0/0 G0/0 :2 S0/0/0 :1 :1
2001:DB8:CAFE:1::/64
2001:DB8:CAFE:2::/64
2001:DB8:FEED:1::/64
2001:DB8:FEED:2::/64
2001:DB8:FEED:3::/64
2001:DB8:FEED:4::/64
2001:DB8:FEED:5::/64
S0/0/0 :2
G0/0 :1
S0/0/0 :1 R1 R2
Static Routes
R1(config)# ipv6 unicast-routing
R1(config)# ipv6 route 2001:db8:feed:1::/ :db8:cafe:2::2
R1(config)# ipv6 route 2001:db8:feed:2::/ :db8:cafe:2::2
R1(config)# ipv6 route 2001:db8:feed:3::/ :db8:cafe:2::2
R1(config)# ipv6 route 2001:db8:feed:4::/ :db8:cafe:2::2
R1(config)# ipv6 route 2001:db8:feed:5::/ :db8:cafe:2::2
Ipv6 unicast-routing – doc says needed to forward IPv6 packets but static routes can be configured without it

21. IPv6 Static Routes Options to reduce routing table:
2001:DB8:CAFE:1::/64
2001:DB8:CAFE:2::/64
2001:DB8:FEED:1::/64
2001:DB8:FEED:2::/64
2001:DB8:FEED:3::/64
2001:DB8:FEED:4::/64
2001:DB8:FEED:5::/64
S0/0/0 :2
G0/0 :1
S0/0/0 :1 R1 R2
R1# show ipv6 route static
<output omitted>
S :DB8:FEED:1::/64 [1/0]
via 2001:DB8:CAFE:2::2
S :DB8:FEED:2::/64 [1/0]
S :DB8:FEED:3::/64 [1/0]
S :DB8:FEED:4::/64 [1/0]
S :DB8:FEED:5::/64 [1/0]
Options to reduce routing table:
Summarized static route
Default static route
(coming soon)
Ipv6 unicast-routing – doc says needed to forward IPv6 packets but static routes can be configured without it

22. IPv6 Static Route Using Exit Interfaces
2001:DB8:CAFE:1::/64
2001:DB8:CAFE:2::/64
2001:DB8:FEED:1::/64
2001:DB8:FEED:2::/64
2001:DB8:FEED:3::/64
2001:DB8:FEED:4::/64
2001:DB8:FEED:5::/64
S0/0/0 :2
G0/0 :1
S0/0/0 :1 R1 R2
Static Route
R2(config)# ipv6 unicast-routing
R2(config)# ipv6 route 2001:db8:cafe:1::/64 serial0/0/0
2001:db8:cafe:2::1
IPv6 CEF (Cisco Express Forwarding) is automatically enabled when ipv6 unicast-routing is enabled.
Because CEF takes care of any recursive lookup issues, it is best to use next-hop address instead of exit-interface.
Next-hop addresses and exit-interfaces should still be used on broadcast networks such as Ethernet.
1True for 5.4 but not in earlier versions
A single lookup is performed using the FIB and adjacency table in the data plane.

23. A Note About CEF for IPv6
R1# show running-config
<output omitted>
ip cef
no ipv6 cef
R1#
R1# show ip cef
Prefix Next Hop Interface
/ no route
R1# show ipv6 cef
%IPv6 CEF not running R1
CEF for IPv4 is enabled by default
CEF for IPv6 is disabled by default
CEF (Cisco Express Forwarding) is a forwarding mechanism to optimize the Layer 3 and Layer 2 lookup processes into a single process.
The behavior of CEFv6 is the same as CEF for IPv4. However, there are new configuration commands for CEFv6 and common commands for both CEFv6 and CEF for IPv4.
The ipv6 cef command enables the central CEFv6 mode.

24. Enabling CEF for IPv6 You may need to enable CEF for IPv6. R1
R1(config)# ipv6 unicast-routing
R1(config)# exit
R1# show running-config
<output omitted>
ip cef
ipv6 cef
R1#
R1# show ipv6 cef
::/0
nexthop 2001:DB8:CAFE:2::2 Serial0/0/0
R1# config t
R1(config)# ipv6 cef
R1(config) R1
CEF IPv6 is now enabled
Prior to IOS 15.x you may need to use this command in addition to ipv6 unicast-routing
You may need to enable CEF for IPv6.

25. 11.4: IPv6 Summary Static Routes

26. Summary Static IPv6 Routes
2001:DB8:CAFE:1::/64
2001:DB8:CAFE:2::/64
2001:DB8:FEED:1::/64
2001:DB8:FEED:2::/64
2001:DB8:FEED:3::/64
2001:DB8:FEED:4::/64
2001:DB8:FEED:5::/64
S0/0/0 :2
G0/0 :1
S0/0/0 :1 R1 R2
Summarize these routes

27. Summarizing IPv6 Routes
Step 1: Starting with left-most bits, identify where the addresses begin to differ (in red)
2001:0db8:feed:0001::/64
2001:0db8:feed:0002::/64
2001:0db8:feed:0003::/64
2001:0db8:feed:0004::/64
2001:0db8:feed:0005::/64
2001:0db8:feed:0001::/64
2001:0db8:feed:0002::/64
2001:0db8:feed:0003::/64
2001:0db8:feed:0004::/64
2001:0db8:feed:0005::/64
Leading 0’s included to make it more obvious

28. Summarizing IPv6 Routes
Step 2: Convert differing hex (in red) to binary
2001:0db8:feed: ::/64
2001:0db8:feed: ::/64
2001:0db8:feed: ::/64
2001:0db8:feed: ::/64
2001:0db8:feed: ::/64
2001:0db8:feed:0001::/64
2001:0db8:feed:0002::/64
2001:0db8:feed:0003::/64
2001:0db8:feed:0004::/64
2001:0db8:feed:0005::/64
Leading 0’s included to make it more obvious

29. Summarizing IPv6 Routes
Step 3: Count the left most matching bits (in red)
2001:0db8:feed: ::/64
2001:0db8:feed: ::/64
2001:0db8:feed: ::/64
2001:0db8:feed: ::/64
2001:0db8:feed: ::/64
= 61 bits or /61
Leading 0’s included to make it more obvious
Note: Summary will also cover the 2001:db8:feed::/64, 2001:db8:feed:6::/64 and 2001:db8:feed:7::/64 subnets.

30. Summarizing IPv6 Routes
Step 4: Add zeros after matching bits and convert Binary back to Hex
2001:0db8:feed: ::
2001:0DB8:FEED:0000::/61 or
2001:0DB8:FEED:0::/61
2001:DB8:FEED::/61
Leading 0’s included to make it more obvious

31. Configuring IPv6 Summary Static Route
2001:DB8:CAFE:1::/64
2001:DB8:CAFE:2::/64
2001:DB8:FEED:1::/64
2001:DB8:FEED:2::/64
2001:DB8:FEED:3::/64
2001:DB8:FEED:4::/64
2001:DB8:FEED:5::/64
S0/0/0 :2
G0/0 :1
S0/0/0 :1 R1 R2
Summary Route
R1(config)# no ipv6 route 2001:db8:feed:1::/ :db8:cafe:2::2
R1(config)# no ipv6 route 2001:db8:feed:2::/ :db8:cafe:2::2
R1(config)# no ipv6 route 2001:db8:feed:3::/ :db8:cafe:2::2
R1(config)# no ipv6 route 2001:db8:feed:4::/ :db8:cafe:2::2
R1(config)# no ipv6 route 2001:db8:feed:5::/ :db8:cafe:2::2
R1(config)# ipv6 route 2001:db8:feed::/ :db8:cafe:2::2
Remove existing routes
Configure summary route

32. Verifying IPv6 Summary Static Route
2001:DB8:CAFE:1::/64
2001:DB8:CAFE:2::/64
2001:DB8:FEED:1::/64
2001:DB8:FEED:2::/64
2001:DB8:FEED:3::/64
2001:DB8:FEED:4::/64
2001:DB8:FEED:5::/64
S0/0/0 :2
G0/0 :1
S0/0/0 :1 R1 R2
Summary Route
R1# show ipv6 route static
<output omitted>
S :DB8:FEED::/61 [1/0]
via 2001:DB8:CAFE:2::2
R1# ping 2001:db8:feed:1::1
Sending 5, 100-byte ICMP Echos to 2001:DB8:FEED:1::1, timeout is 2 seconds:
!!!!!
R1#

33. 11.5: IPv6 Default Static Route

34. IPv6 Static Default Route
IPv6 default static route
Router(config)# ipv6 route ::/0 {exit-intf | ipv6-address}
:: “all zeroes” prefix
“zero” prefix-length
IPv4 default static route
Router(config)# ip route {exit-intf | ipv4-add}
Similar to configuring default route in IPv4.
The more complete syntax is similar to that for IPv4
For the purposes of this section, assume that you are familiar with configuring IPv4 static routes.

35. Configuring IPv6 Default Static Routes
2001:DB8:CAFE:1::/64
2001:DB8:CAFE:2::/64
2001:DB8:FEED:1::/64
2001:DB8:FEED:2::/64
2001:DB8:FEED:3::/64
2001:DB8:FEED:4::/64
2001:DB8:FEED:5::/64
S0/0/0 :2
G0/0 :1
S0/0/0 :1 R1 R2
Default Route
R1(config)# no ipv6 route 2001:db8:feed::/ :db8:cafe:2::2
R1(config)# ipv6 route ::/0 2001:db8:cafe:2::2
Remove existing summary route
Configure default route

36. Verifying IPv6 Default Static Routes
2001:DB8:CAFE:1::/64
2001:DB8:CAFE:2::/64
2001:DB8:FEED:1::/64
2001:DB8:FEED:2::/64
2001:DB8:FEED:3::/64
2001:DB8:FEED:4::/64
2001:DB8:FEED:5::/64
S0/0/0 :2
G0/0 :1
S0/0/0 :1 R1 R2
Default Route
R1# show ipv6 route static
<output omitted>
S ::/0 [1/0]
via 2001:DB8:CAFE:2::2
R1# ping 2001:db8:feed:1::1
Sending 5, 100-byte ICMP Echos to 2001:DB8:FEED:1::1, timeout is 2 seconds:
!!!!!
R1#

37. For more information please check out my Cisco Press book and video series:
IPv6 Fundamentals: A Straightforward Approach to Understanding IPv6
By Rick Graziani
ISBN-10:
IPv6 Fundamentals LiveLessons: A Straightforward Approach to Understanding IPv6
By Rick Graziani
ISBN-10:

38. 11: IPv6 Routing Table and Static Routes
Rick Graziani
Cabrillo College