Technical data

4. Packages
VPN_CARD_TYPE This configuration variable defines the type of the VPN accelerator.
The following values are supported:
• hifn7751 - Soekris vpn1401 and vpn1411
• hifnhipp
4.12. IPv6 - Internet Protocol Version 6
4.12.1. Introduction
This package enables fli4l to support IPv6 in many ways. This includes informations about
the IPv6 address of the router’s IPv6 (sub) networks managed by it, predefined IPv6 routes
and firewall rules regarding IPv6 packets. Further other IPv6-based services can be provided,
such as configuration via DHCPv6. Last but no least it is possible to automatically establish
tunnels to IPv6 providers. This currently works only with so-called 6in4 tunneling as supported
by the provider “SixXS”. Other technologies (AYIYA, 6to4, Teredo) are not supported at the
moment.
IPv6 is the successor of the internet protocol IPv4. It was developed mainly to enlarge the
relatively small amount of unique internet addresses: While IPv4 supports approximately 2
32
addresses,
9
in IPv6 2
128
are possible. Each communicating IPv6 host can thus have a unique
address and no longer has to rely on techniques such as NAT, PAT, masquerading a.s.o.
Besides this aspect topics such as self-configuration and safety concerns also played a role in
the development of the IPv6 protocol. This will be carried out in later sections.
The biggest problem with IPv6 is its spread: Currently IPv6 –compared with IPv4 – is rarely
used. The reason is that IPv6 and IPv4 are technically incompatible and thus all software and
hardware components involved in packet forwarding in the internet have to be retrofitted for
IPv6. Certain services such as DNS (Domain Name System) must be extended in accordance
with IPv6.
This is a vicious circle: The low spreading of IPv6 with service providers on the internet leads
to disinterest on the part of router manufacturers to equip their devices with IPv6 functionality,
which in turn means that service providers fear the transition to IPv6 because they fear that
it’s not worth the effort. Only slowly the mood is changing in favour of IPv6 mostly because
of the increasing pressure from shortness of IPv4 address supplies.
10
4.12.2. Address Format
An IPv6 address consists of eight two-byte values listed in hexadecimal notation:
Example 1: 2001:db8:900:551:0:0:0:2
Example 2: 0:0:0:0:0:0:0:1 (IPv6-loopback-address)
To make the addresses a little clearer, successive zeros are merged by removing them, and
only two successive colons remain. The above addresses may therefore be rewritten as:
Example 1 (compact): 2001:db8:900:551::2
Example 2 (compact): ::1
9
only nearly because some addresses are used for specialized purposes, such as for broadcast and multicasting
10
The last IPv4 address blocks have been assigned by the IANA by now.
133