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IPv6 on FI

The Faculty of Informatics has a network prefix assigned by the CESNET provider 2001:0718:0801:0200::/56 .

If you wish to set up IPv6 on your machine, contact your administrator at unix@fi.muni.cz . The preferred option is to send us a DUID, or you can set the address statically. More about both options below. In case of configuring the IPv6 address on your managed machine, we will also include this address into DNS (AAAA record).

Stateful configuration

Interestingly, we will describe the convention that we follow when assigning addresses. Its understanding is not necessary, if you wish to set up an IPv6 address, contact us and we will give you the address.

Machines with a public IPv4 address are assigned a public IPv6 address that logically corresponds to an IPv4 address as follows:

  • Take an address machine 147.251.42.106 in the net 147.251.42.0/24 .
  • First 16 bits ( 147.251 ) belong to the MU network, adding 8 more bits ( 42 ) the (sub) network address is generated, that is 147.251.42.0/24 . The remaining 8 bits ( 106 ) identifies the machine inside the network.
  • 42 is hexadecimal 2a , 106 Yippee 6a .
  • So let's take our 56 bits ( 2001:0718:0801:02 ), we add to them 2a to form a (sub) network 2001:718:801:22a::/64 that corresponds to a (sub) network 147.251.42.0/24 .
  • We will add 6a and we get the address 2001:718:801:22a::6a

The gateway is usually at 1 (excluding network 147.251.48.0/24 , respectively 2001:718:801:230::1/64 where 1 is for historical reasons Aisa; gateway is at 147.251.48.14 , respectively 2001:718:801:230::e ).

DHCPv6

The preferred method is state autoconfiguration (DHCPv6). You only need to know the DUID (DHCP Unique Identifier) of the device. In practice, however, there is a problem with detecting / setting the DUID of a client. It depends on the DHCP client and it is not always easy. (We usually detect it by scanning network traffic using a tool tcpdump , a procedure that works independently of the DHCP client on the machine.)

Static configuration

On servers we often use manual (static) configuration. If you want to set IPv6 for example with machines with IPv4 address 147.251.42.106 , we set a logically matching IPv6 address and the configuration will look like this:

Adresa: 2001:718:801:22a::6a/64
Gateway: 2001:718:801:22a::1

Stateless configuration

SLAAC

When stateless autoconfiguration ( SLAAC ) the client chooses the address itself. This method is used in Eduroam and wlan_fi wireless networks as well as some virtual machines in the faculty cloud infrastructure Stratus.FI (virtual machines are typically assigned a NAT private IPv4 address and a public IPv6 address).