Tuesday, April 6, 2010


We'll now set up IPv6 and some routing between them with a simple topology as shown:

This would be the addressing scheme used:
SubnetA: fd00:0001::/32
SubnetB: fd00:0002::/32
Link: fd00:0003::/32

To begin, we'll need to start all our routers to do IPv6 routing. To do this, go under Global Configuration of all routers and type:
ipv6 unicast-routing

Now we can begin assigning IP addresses. For the LANs, we'll be using Loopbacks. For RA, do this:
in f0/0
ipv6 add fd00:3::1/32
no shut
in lo0
ipv6 add fd00:1::1/32
no shut

Similarly, on RB, do this:
in f0/0
ipv6 add fd00:3::2/32
no shut
in lo0
ipv6 add fd00:2::1/32
no shut

We can now ping across the link by typing:
ping fd00:1::1

Right now, as expected, we can only ping links that are directly connected. We'll have to turn on routing protocols. These are the routing protocols that can support IPv6:
-EIGRP for IPv6
-IS-IS for IPv6

Right now, we'll configure RIPng. The configuration is different in that you won't have any network statement:
ipv6 router rip 1

To turn on RIP, you have to go under the interfaces:
in f0/0
ipv6 rip 1 en
in lo0
ipv6 rip 1 en

When the same has been done on both routers, you can see the route by typing:
show ipv6 route

You can also verify your interfaces using:
show ipv6 int br

There are currently many migration strategies for IPv6 to provide a smooth, non-pressured transition. The strategies are:
-Dual-stack routers
-NAT - Protocol Translation (NAT-PT)

Dual-stacking means that the routers will use IPv4 and IPv6 together. Clients using IPv4 will connect out through IPv4 and IPv6 clients will connect out through IPv6. If a version 4 client wants to communicate with a version 6 web site, the ISPs can actually automatically NAT the address to an IPv6 address. The same can be said for the other way round.

Tunneling allows IPv4 hosts to communicate through the IPv6 internet by encapsulating the IPv4 packets in IPv6 headers as it enters the IPv6 network and decapsulating the packet as it returns to IPv4. You can also run IPv6 through IPv4 by encapsulating IPv6 packets with a IPv4 header.

NAT-PT is a type of NATting that allows IPv4 addresses to be translated into IPv6. Similar can be said for IPv6 clients who want to access IPv4 networks. NAT still works exactly the same, it's just using a different translation pool. Static NAT, NAT overload and so on will still work the same.

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