IPv 6 Basics Run Down

How to configure IPV6 on a router

R1(config)#ipv6 unicast-routing      /enables ipv6 routing on all interfaces

                       (isp prefix 48 bits) (subnet 16 bits) (Interface ID/host ID 64 bits)

R1(config-if)#ipv6 address 2233:0:2222:11:0000:0000:0000:0001/64

Note: can have ipv6 and an ipv4 address on one interface.

Show command:

show interfaces

show ipv6 interface fa0/0

show ipv6 interface brief

show ipv6 router connected

IPv6 Break down:
IPv4 address:   /24
128.102 is the network id portion
11 is the subnet id
0 is the host id
Class B address which is /16
Hosts in this case is easy:    32 – 24 = host bits = 8 = 2^8-2= 256-2= 254 hosts
Subnet                            24-16 = 8 bits = 2^8 =256 subnets
IPv6 similarities:
2233:0000:2222:0011              :0000:0000:0000:0000/64 being used.
(isp prefix 4 x 16 bit quartets( 0011 is subnet intranet))  (last 4 quartets is

interface ID/Host ID)
How to abbreviate IPv6:
Example: 2233:0000:2222:0011:0000:0000:0000:0000/64
1. leading zero of a quartet can be omitted
2. All quartets can be abbreviated 0000 to :0:
3. 1 instance of multiple 0000:0000 to ::





Run show commands to see running-config and how you can dual IPv4 with IPV6 on same interface. Cool huh!

R1#show running-config        /out put below.

——some out surpressed for ease of reading——

ipv6 unicast-routing
no ftp-server write-enable
interface Loopback0
 no ip address
interface Ethernet0
 description LAN inside$FW_INSIDE$
 ip address
 ip access-group 100 in
 ip nat inside
 ip virtual-reassembly
 ipv6 address 2233:0:2222:11::1/64
 no cdp enable
 hold-queue 32 in


Show command output here.

R5#sh ipv6 inter e0
Ethernet0 is up, line protocol is up
  IPv6 is enabled, link-local address is FE80::213:C3FF:FE42:6B6D
  Description: LAN inside$FW_INSIDE$
  Global unicast address(es):
    2233:0:2222:11::1, subnet is 2233:0:2222:11::/64
  Joined group address(es):
  MTU is 1500 bytes
  ICMP error messages limited to one every 100 milliseconds
  ICMP redirects are enabled
  ND DAD is enabled, number of DAD attempts: 1
  ND reachable time is 30000 milliseconds
  ND advertised reachable time is 0 milliseconds
  ND advertised retransmit interval is 0 milliseconds
  ND router advertisements are sent every 200 seconds
  ND router advertisements live for 1800 seconds
  Hosts use stateless autoconfig for address


Cold Memory:

FF02 is multicast of some sort

FE80 is Link-local address

Global Unicast :2233:0:2222:11::1, subnet is 2233:0:2222:11::/64


R5#sho ipv6 inter brief
Ethernet0                  [up/up]
Ethernet1                  [up/down]
Ethernet2                  [down/down]
FastEthernet1              [down/down]
FastEthernet2              [up/up]
FastEthernet3              [down/down]
FastEthernet4              [down/down]
Loopback0                  [up/up]


R5#show ipv6 route connected
IPv6 Routing Table – 4 entries
Codes: C – Connected, L – Local, S – Static, R – RIP, B – BGP
       U – Per-user Static route
       I1 – ISIS L1, I2 – ISIS L2, IA – ISIS interarea, IS – ISIS summary
       O – OSPF intra, OI – OSPF inter, OE1 – OSPF ext 1, OE2 – OSPF ext 2
       ON1 – OSPF NSSA ext 1, ON2 – OSPF NSSA ext 2
C   2233:0:2222:11::/64 [0/0]
     via ::, Ethernet0


Practice Abbreviatiing IPv6


example 1:


example 2:



example 3:

1234:1234:0000:0000:0000:0000:3456:3434 /128

Types of casts:

(**broadcast is not longer used in IPv6**)
Unicast– 1 to 1

Multicast – 1 to specfic many (example: FF00::/8
Anycast -1 to closest device

Types of addresses ipv6:

Global Unicast – similar to Public IP from the ISP

Link-Local  Similar to the MAC address (FE80)
FE80:AAAA.AAAA.AAAA  (FE80 + Mac address)

Site-Local Private addressesing side (FEC0)
Loopback are all 0s and then a 1 like this (::1/128 )
no broadcast in IPv6 any more..

Note: advantage of IPv6 is route summarizing
IPv4 compatible
1st 96 bits used last 16 bits for ipv6 compatible:


:D1 90:4E 71

D1 = 209
90 = 144
4E = 78
71 = 113                    Hex
                                    0-9   = 0 – 9
256 |   16  | 1              A-F   = 10 – 15
             D     1   = 209
ipv4 compatible:

DHCP or Autoconfiguration IPv6 world –RFC 2462 excerpts from below…


Stateful – DHCPv6 autoconfiguration – obtian Ipv6 address via server

In the stateful autoconfiguration model, hosts obtain interface
   addresses and/or configuration information and parameters from a
   server.  Servers maintain a database that keeps track of which
   addresses have been assigned to which hosts. The stateful
   autoconfiguration protocol allows hosts to obtain addresses, other
   configuration information or both from a server.  Stateless and
   stateful autoconfiguration complement each other. For example, a host
   can use stateless autoconfiguration to configure its own addresses,
   but use stateful autoconfiguration to obtain other information.
   Stateful autoconfiguration for IPv6 is the subject of future work

Stateless – Static – local host creates its own LINK-Local address

IPv6 defines both a stateful and stateless address autoconfiguration
   mechanism. Stateless autoconfiguration requires no manual
   configuration of hosts, minimal (if any) configuration of routers,
   and no additional servers.  The stateless mechanism allows a host to
   generate its own addresses using a combination of locally available
   information and information advertised by routers. Routers advertise
   prefixes that identify the subnet(s) associated with a link, while
   hosts generate an “interface identifier” that uniquely identifies an
   interface on a subnet. An address is formed by combining the two. In
   the absence of routers, a host can only generate link-local
   addresses. However, link-local addresses are sufficient for allowing
   communication among nodes attached to the same link.


How host creates link-local address:

Host sends out (NS) neighbor solicitations to check to see if anyone else is using this link-local address.

NS destination address FF02::1 is a multicast to ALL Nodes!

if NS finds a match of some host using same address host responds with NA neighbor advertisment from responding Host A (NA). The NS host will disable its link-local and retry another link-local address.

So host A sends out NS to host B host B sends back NA host A recalculates link-local address and retries its NS messages until it doesnt find a similar link-local address.

Process is call DAD     Duplicate Address Detetection


Just the basics for Ipv6



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