Jul 27 2011   11:34PM GMT

IPv6 Example 1 – Private IPs

Joshua Wood Joshua Wood Profile: Joshua Wood

IPv6 Example 1 – Private IPs

Hi all, so in the last post I discussed a need for some barebones examples. Mostly in the context of IPv6 day and the interest that will have generated. In this blog post I want to go through a really basic example of a private IPv6 address and how to use it on a Cisco router.

The first thing that you will need is a private IPv6 IP. These are somewhat pointless when looked at from the typical world of IPv4 where they were needed in order to stave off exhaustion but they have their purpose. One such purpose is just what we are doing here, testing. You can get one here. A website that gives a very brief explanation of IPv6 as well as an easy way to generate private IPv6 IPs.

Once you have that you need two routing devices for our example. Anything that can successfully run IPv6 will do which should be all current routers or layer 3 switches. Once you have your routers setup with a cable between two ports here is where the configuring starts.

In the Cisco world you need to turn on IPv6 routing. Yes, depending on your IOS version it doesn’t come turned on by default. Whether this was a security feature or a resource feature I don’t know but in order to turn IPv6 on you use the command “ipv6 unicast-routing”. This effectively activates the ability to use IPv6 in your router.

Now the next part is pretty simple … you assign the IPs. You use the slightly modified command “ipv6 address XX/XX” in order to assign your IPv6 address to the interface. Just below is my configuration on R2 or my two router setup.

R2#sh run int fa0/0
interface FastEthernet0/0
no ip address
duplex auto
speed auto
ipv6 address FD34:41B7:DFE:78FF::1/64

As you can see there isn’t much to it. And here is R1.

R1#sh run int fa0/0
interface FastEthernet0/0
no ip address
duplex auto
speed auto
ipv6 address FD34:41B7:DFE:78FF::2/64
ipv6 address FD34:41B7:DFE:78FF::3/64

And a ping from R1 to R2

R1#ping ipv6 FD34:41B7:DFE:78FF::1

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to FD34:41B7:DFE:78FF::1, timeout is 2 seconds:
Success rate is 100 percent (5/5), round-trip min/avg/max = 8/13/32 ms

Now R1 has something that might be different for some people. It has two IPs but doesn’t have the secondary command. This is new IPv6 and is much easier than the traditional need for the secondary command.

Hopefully that was useful and hopefully I can get some feedback on these short how-tos so that I can include information that people request.

Until next time,
TechStop (JW)

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