IPv6 Routing – Static and Basics

Static Routing

From my previous post on addressing, the routing table below is for R1 and R2 which are connected using their Fa 0/0 interfaces. The [updated] option gives the time the route was installed into the routing table.

R1#show ipv6 route updated
IPv6 Routing Table - default - 3 entries
Codes: C - Connected, L - Local, S - Static, U - Per-user Static route
B - BGP, HA - Home Agent, MR - Mobile Router, R - RIP
H - NHRP, I1 - ISIS L1, I2 - ISIS L2, IA - ISIS interarea
IS - ISIS summary, D - EIGRP, EX - EIGRP external, NM - NEMO
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, l - LISP
C 2001:9999:9999:CAFE::/64 [0/0]
   via FastEthernet0/0, directly connected
       Last updated 02:31:42 29 July 2018
L 2001:9999:9999:CAFE::1/128 [0/0]
   via FastEthernet0/0, receive
      Last updated 02:31:43 29 July 2018
L FF00::/8 [0/0]
   via Null0, receive
      Last updated 17:53:54 28 July 2018

R2#show ipv route updated
IPv6 Routing Table - default - 5 entries
<omitted for brevity>
C 2001:2222::/64 [0/0]
   via Loopback0, directly connected
      Last updated 17:53:56 28 July 2018
L 2001:2222::1/128 [0/0]
   via Loopback0, receive
       Last updated 17:53:56 28 July 2018
NDp 2001:9999:9999:CAFE::/64 [2/0]
   via FastEthernet0/0, directly connected
       Last updated 02:51:09 29 July 2018
L 2001:9999:9999:CAFE:C802:4FF:FEA0:8/128 [0/0]
   via FastEthernet0/0, receive
      Last updated 02:51:10 29 July 2018
L FF00::/8 [0/0]
   via Null0, receive
Last updated 17:53:55 28 July 2018

The R2 learned prefix in red above is from the neighbour discovery process and P means the prefix was learnt thorough that interface.   We could have R2 consider Fa 0/0 the default route by adding [default] option under the interface (in red below)

R2(config)#int fa 0/0
R2(config-if)#ipv6 address autoconfig ?
default Insert default route
<cr>

R2(config-if)#ipv6 address autoconfig default


R2#show ipv route
IPv6 Routing Table - default - 6 entries
Codes: C - Connected, L - Local, S - Static, U - Per-user Static route
B - BGP, HA - Home Agent, MR - Mobile Router, R - RIP
H - NHRP, I1 - ISIS L1, I2 - ISIS L2, IA - ISIS interarea
IS - ISIS summary, D - EIGRP, EX - EIGRP external, NM - NEMO
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, l - LISP
ND ::/0 [2/0]
via FE80::C801:56FF:FE00:8, FastEthernet0/0
C 2001:2222::/64 [0/0]
via Loopback0, directly connected
L 2001:2222::1/128 [0/0]
via Loopback0, receive
NDp 2001:9999:9999:CAFE::/64 [2/0]
via FastEthernet0/0, directly connected
L 2001:9999:9999:CAFE:C802:4FF:FEA0:8/128 [0/0]
via FastEthernet0/0, receive
L FF00::/8 [0/0]
via Null0, receive

A router doesn’t forward packets for a link-local address!  There isn’t a need to put it in the routing table.  Older Cisco IOS had a route to Null 0 for FE80::/10 prefixes, and although it’s not there it can still be seen in the IPv6 CEF table.  Only the default route uses both the Link local and exit interface.  See Below:

R2#show ipv6 cef
::/0
nexthop FE80::C801:56FF:FE00:8 FastEthernet0/0
::/127
discard
2001:2222::/64
attached to Loopback0
2001:2222::1/128
receive for Loopback0
2001:9999:9999:CAFE::/64
attached to FastEthernet0/0
2001:9999:9999:CAFE:C802:4FF:FEA0:8/128
receive for FastEthernet0/0
FE80::/10
receive for Null0
FF00::/8
multicast
R2#

Ping

Ping works almost the same but if you are pinging …

  • GUA – No need for more info
  • LLA – Need to specify the exit interface too as it’s not guaranteed the address is unique.  Specify the FULL address in the format you’ll get in the error message!
R2#ping FE80::C801:56FF:FE00:8
Output Interface: Fa 0/0
% Invalid interface. Use full interface name without spaces (e.g. Serial0/1)
Output Interface: Fastethernet 0/0
% Invalid interface. Use full interface name without spaces (e.g. Serial0/1)
Output Interface: Fastethernet0/0
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to FE80::C801:56FF:FE00:8, timeout is 2 seconds:
Packet sent with a source address of FE80::C802:4FF:FEA0:8%FastEthernet0/0
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 12/28/56 ms
R2#ping 2001:9999:9999:CAFE::1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2001:9999:9999:CAFE::1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 12/29/80 ms
R2#

Static Routes

Here is the static route for R2 to ping the loopback of R1!  Firstly I get rid of the default route, test, then add the static route.

R2#ping 2001:1111:1111::1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2001:1111:1111::1, timeout is 2 seconds:
!!!!! #Reachable via default
Success rate is 100 percent (5/5), round-trip min/avg/max = 8/14/20 ms

R2#show ipv6 route
IPv6 Routing Table - default - 6 entries
Codes: C - Connected, L - Local, S - Static, U - Per-user Static route
B - BGP, HA - Home Agent, MR - Mobile Router, R - RIP
H - NHRP, I1 - ISIS L1, I2 - ISIS L2, IA - ISIS interarea
IS - ISIS summary, D - EIGRP, EX - EIGRP external, NM - NEMO
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, l - LISP
ND ::/0 [2/0]
via FE80::C801:56FF:FE00:8, FastEthernet0/0
C 2001:2222::/64 [0/0]
via Loopback0, directly connected
L 2001:2222::1/128 [0/0]
via Loopback0, receive
NDp 2001:9999:9999:CAFE::/64 [2/0]
via FastEthernet0/0, directly connected
L 2001:9999:9999:CAFE:C802:4FF:FEA0:8/128 [0/0]
via FastEthernet0/0, receive
L FF00::/8 [0/0]
via Null0, receive
R2#conf t
Enter configuration commands, one per line. End with CNTL/Z.
R2(config)#do show run int fa 0/0
Building configuration...

Current configuration : 106 bytes
!
interface FastEthernet0/0
no ip address
duplex auto
speed auto
ipv6 address autoconfig default
end

R2(config)#interface FastEthernet0/0
R2(config-if)#no ipv6 address autoconfig default
R2(config-if)#ipv6 address autoconfig

R2(config-if)#do show ipv route
IPv6 Routing Table - default - 5 entries
Codes: C - Connected, L - Local, S - Static, U - Per-user Static route
B - BGP, HA - Home Agent, MR - Mobile Router, R - RIP
H - NHRP, I1 - ISIS L1, I2 - ISIS L2, IA - ISIS interarea
IS - ISIS summary, D - EIGRP, EX - EIGRP external, NM - NEMO
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, l - LISP
C 2001:2222::/64 [0/0]
via Loopback0, directly connected
L 2001:2222::1/128 [0/0]
via Loopback0, receive
NDp 2001:9999:9999:CAFE::/64 [2/0]
via FastEthernet0/0, directly connected
L 2001:9999:9999:CAFE:C802:4FF:FEA0:8/128 [0/0]
via FastEthernet0/0, receive
L FF00::/8 [0/0]
via Null0, receive
R2(config-if)#end

R2#ping 2001:1111:1111::1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2001:1111:1111::1, timeout is 2 seconds:

% No valid route for destination
Success rate is 0 percent (0/1)

R2(config)#ipv6 route 2001:1111:1111::1/128 2001:9999:9999:CAFE::1
R2(config)#end

R2#show ipv route
IPv6 Routing Table - default - 6 entries
Codes: C - Connected, L - Local, S - Static, U - Per-user Static route
       B - BGP, HA - Home Agent, MR - Mobile Router, R - RIP
       H - NHRP, I1 - ISIS L1, I2 - ISIS L2, IA - ISIS interarea
       IS - ISIS summary, D - EIGRP, EX - EIGRP external, NM - NEMO
       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, l - LISP
S   2001:1111:1111::1/128 [1/0]
     via 2001:9999:9999:CAFE::1
C   2001:2222::/64 [0/0]
     via Loopback0, directly connected
L   2001:2222::1/128 [0/0]
     via Loopback0, receive
NDp 2001:9999:9999:CAFE::/64 [2/0]
     via FastEthernet0/0, directly connected
L   2001:9999:9999:CAFE:C802:4FF:FEA0:8/128 [0/0]
     via FastEthernet0/0, receive
L   FF00::/8 [0/0]
     via Null0, receive


R2#ping 2001:1111:1111::1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2001:1111:1111::1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 12/15/24 ms
R2#

You can use a LLA for the static route, but again, you’ll need to specify the exit interface.

Summarisation

This is the same as in IPv4.  Find the last matching bit of the host portion.

CEF

This is the same concept as IPv4.  The faster a packet can be processed with the minimum of intervention the better.  Again, two tables…

  • FIB – Ordered list of prefixes, Layer 3 networks with their conjugate next-hop information
  • Adjacency Table – L2 information for next hops built from the IPv6 neighbour cache.
R2#show ipv6 cef
::/0
no route
::/127
discard
2001:1111:1111::1/128
nexthop 2001:9999:9999:CAFE::1 FastEthernet0/0
2001:2222::/64
attached to Loopback0
2001:2222::1/128
receive for Loopback0
2001:9999:9999:CAFE::/64
attached to FastEthernet0/0
2001:9999:9999:CAFE::1/128
attached to FastEthernet0/0
2001:9999:9999:CAFE:C802:4FF:FEA0:8/128
receive for FastEthernet0/0
FE80::/10
receive for Null0
FF00::/8
multicast
R2#

R2#show adjacency
Protocol Interface Address
IPV6 FastEthernet0/0 2001:9999:9999:CAFE::1(10)
IPV6 FastEthernet0/0 FE80::C801:56FF:FE00:8(2)

R2#show adjacency detail
Protocol Interface Address
IPV6 FastEthernet0/0 2001:9999:9999:CAFE::1(10)
0 packets, 0 bytes
epoch 0
sourced in sev-epoch 1
Encap length 14
CA0156000008CA0204A0000886DD
IPv6 ND
IPV6 FastEthernet0/0 FE80::C801:56FF:FE00:8(2)
0 packets, 0 bytes
epoch 0
sourced in sev-epoch 1
Encap length 14
CA0156000008CA0204A0000886DD
IPv6 ND
R2#

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