IPv6 Address Types

IPv6 looks different than IPv4 but there are some similarities. For example we have unicast addresses and we still have a “public” and “private” range. We use different names for these but the idea is the same. One of the differences is that IPv6 has some additional unicast address types.

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IPv6 Address Assignment

In this blog we’ll take a look how you can create IPv6 prefixes and subnets so that you can configure your entire network with IPv6. We’ll start at the top where IANA (Internet Assigned Numbers Authority) is responsible for the global coordination of the IPv4 and IPv6 address space and move our way all the way to the bottom where we assign subnets and IPv6 addresses to our routers, switches and VLANs.

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IPv6 EUI-64

EUI-64 (Extended Unique Identifier) is a method we can use to automatically configure IPv6 host addresses. An IPv6 device will use the MAC address of its interface to generate a unique 64-bit interface ID. However, a MAC address is 48 bit and the interface ID is 64 bit. What are we going to do with the missing bits?

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IPv6 Summarization

Summarizing IPv6 prefixes is similar to IPv4 summarization, the big difference is that IPv6 uses 128 bit addresses compared to 32 bits for IPv4 and IPv6 uses hexadecimal addresses.

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Stateless autoconfiguration for IPv6

Stateless autoconfiguration for IPv6 is like a “mini-DHCP” server for IPv6. Routers running IPv6 can give the prefix of the network and a gateway address to clients looking for an IPv6 address. IPv6 uses the NDP (Neighbor Discovery Protocol) and one of the things this protocol offers is RS (Route Solicitation and (RA) Router Advertisement messages that help an IPv6 device to automatically configure an IPv6 address. Let’s take a look at a configuration example:

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Cisco DHCPv6 Server Configuration

In this blog we’ll take a look at DHCPv6 so we can automatically assign IPv6 addresses to our hosts. The functionality of DHCPv6 is the same as DHCP for IPv4 but there are some differences. First of all, DHCPv6 supports two different methods:

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How to configure IPv6 Static Route

If you know how to configure a static route for IPv4 then you shouldn’t have any issues with IPv6 static routes. The configuration and syntax are similar, there are only some minor differences. In this blog, we will discuss how to configure all IPv6 static route types.

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IPv6 Access-list on Cisco IOS

We can use access-lists for filtering (blocking packets) or selecting traffic (for VPNs, NAT, etc).

This also applies to IPv6 access-lists which are very similar to IPv4 access-lists. However, there are two important differences:

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How to configure IPv6 tunneling over IPv4

Since IPv4 and IPv6 are not compatible with each other we need some migration strategies. One technique that we can use is tunneling. Basically it means that we encapsulate IPv6 packets into IPv4 packets (or the other way around) so that it can be routed. In this blog, we’ll discuss how to configure IPv6 static tunneling over an IPv4 network, there are two methods:

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How to configure IPv6 Automatic 6to4 Tunneling

Dynamic multipoint IPv6 tunnels are another migration technique we can use. It’s called dynamic because we don’t have to specify the end-point IPv4 address ourselves but its being automatically determined. The downside of multipoint IPv6 tunnels is that they don’t support IPv6 IGPs. You have to use static routes or BGP.

There are two different flavors:

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