Configuring network interfaces Configure IPv6 addressing support
Digi TransPort® Routers User Guide
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Configure IPv6 addressing support
IPv6 is an updated version of the Internet Protocol (IP). Until recently, the Internet has used a
previous version, IPv4.
IPv4 addresses are 32 bits long. Over 4 billion addresses are available through IPv4, though not all the
addresses are usable. IPv6 addresses are 128 bits long. Taking into account the structure of the IPv6
address, there are 4.6x10
18
globally routable addresses available. This equates to approximately 650
million IP addresses for each person in the world.
Since every device can have a globally routable IPv6 address, there is no need for NAT with IPv6. This
means it is very important to properly configure IP filters and firewall rules to prevent direct attacks
on hosts on the LAN networks.
By default, IPv6 is disabled on TransPort routers.
TransPort devices do not support static configuration of IPv6 addresses. Instead, it relies on learning
prefixes, routes, and DNS addresses from an upstream router.
IPv6 support is for Ethernet interfaces only
You can configure IPv6 addressing on Ethernet interfaces eth 0, eth 1, eth 2, and eth 3 only. There is
no IPv6 support on other Ethernet interfaces, or other interfaces, such as PPP, GRE tunnel, or
OpenVPN.
IPv6 modes
You can configure Ethernet interfaces to operate in one of two IPv6 modes: WAN mode or LAN mode.
WAN mode
In WAN mode, the interface listens for Router Advertisement (RA) messages, if enabled. The interface
assigns itself an IPv6 address from any suitable prefixes it sees in the RA messages (for example, 64-
bit, on-link, auto-config bit set). Learned prefixes and routes are added to the IPv6 routing table.
Advertised DNS addresses are added to the list of learned DNS addresses.
By default, if DHCPv6 is enabled, the interface attempts to obtain an IPv6 address using DHCPv6. The
router also attempts to learn prefixes from the upstream router for prefix delegation. DNS addresses
learned through DHCPv6 are added to the list of learned DNS addresses.
Default routes are added into the IPv6 routing table when the router sees RA messages from an
upstream router. If RA learning is disabled, no default routes are added to the routing table. For this
reason, Digi recommends you enable RA learning.
LAN mode
In LANmode, the interface subnets delegated prefixes, assigns itself addresses from these subnetted
prefixes, advertises the subnetted prefixes in RA messages, and assigns downstream hosts an
address from this prefix via DHCPv6. RA messages include the subnet prefix in them, so downstream
hosts can use SLAAC to assign itself an address from this prefix.
The DHCPv6 server advertises addresses in the DNS address list, provided the addresses are not link-
local addresses.
Typical IPv6 configuration
A typical IPv6 configuration includes:
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