MNET Services>Telecom Data Networking>IPv6>General

This documentation is preliminary and is likely to change before becoming final. Do not implement to it yet. Check for the next update by February 2012.

What is IPv6?

  • It's a new, network-level protocol originally based on IPv4; addresses look like 192.168.4.
  • IPv6 addresses look like 2607:f830:3400:0001::1.
  • IPv6 addresses Still use /## for network, but ## can go up to 128.
  • It only replaces IP: TCP and UDP are the old familiar faces.


  • IPv6 is not the same as IPv4: it's different!
  • To start with, there's no's all multicast.
  • Further, much of layer 2 (ARP, BOOTP, DHCP) are now layer 3.
  • And, IPSEC is required in all implementations.
  • Finally, ICMP is now much more than "ping:"
    • Some parts are required for IPv6 operation.
    • Some parts (line "ping") are still optional.
    • Some parts you should never allow.

Why Do It?

  • The world is running out of IPv4 addresses.
  • Our network is safe: MN.IT has enough IPv4 IP addresses to meet the foreseeable demand, so you can keep getting IPv4 addresses as needed for your clients and servers.
  • That's assuming, of course, that there isn't a disruptive new application that requires on the order of one IP address per person.
  • At some point in the next year, there will be customers - such as citizens - coming to you who only have IPv6 addresses. That's the problem that we need to address.

What Exactly Needs Doing?

  • Adopting IPv6 means adding it to existing services.
  • IPv4 will be with us for a long time: both IPv4 and IPv6 will coexist for years.
  • The key need is for public-facing systems (e.g., web servers).
  • Internal and back end servers can be done later (or maybe never).

Converting Applications

  • Converting any one application is easy, much easier than the conversion from, say Novell IPX to TCP/IP.
  • However, there are LOTS of applications.
  • This is very much like the Y2K problem: you have to look through the application to find where they make assumptions and fix them.
  • In specific cases, you may be able to do IPv6 to IPv4 address conversion: this is not a solution that will work in all - or even most - cases.

Typical Assumptions

length (bits)32128
contains0-9, .0-9, a-f, :
largest mask32128
typical #IPs1up to 6
client IP changerareoften
client name in DNSsometimesrare
client IP in DNSoftenrare
public server in DNSyesyes
public server static IPyesyes

Security Issue Highlights

  • Hosts have lots of addresses and they can change: do filters at the network, not IP level.
  • Static assignment for servers, dynamic for clients.
  • You'll need to turn on (some) ICMP.
  • You'll need to block (some) multicast.