IPv6: Difference between revisions

This is how we route and assign IPv6 on DSL connections.

 

Customers are allocated a /48 block of addresses - this is usually per customer, and so a customer with multiple circuits or sites will have a /64 allocated from the larger /48 block. A /48 contains 65536 /64's and a /64 subnet is 18 million trillion addresses.

 

(Here, Customer Premises Equipment (CPE) refers to the router belonging to the customer which is being used at their end of the broadband line, and L2TP Network Server (LNS) refers to our equipment at our end of the broadband link.)

 

When DHCPv6 is enabled, the CPE sends a DHCPv6 Solicitation to the IPv6 broadcast address, containing a list of options that it requires.

Once we receive the DHCPv6 Solicitation, the LNS you are connected to will send a reply containing responses to the options requested. The CPE can then take the options and apply them as appropriate.

 

In the DHCPv6 Solicitation, you would usually request DHCPv6 IA (Option 3, Identity Association for Non-temporary Address) to assign your IPv6 'WAN' address. This address is a single IPv6 address in the form of:

2001:8b0:1111:1111:0:ffff:[your IPv4 WAN in HEX]

We also respond to DHCPv6 Prefix Delegation (Option 25, Identity Association for Prefix Delegation, responded to by Option 26, IA Prefix) from the CPE and we'll tell the CPE one of the /64 Blocks. -this may be requested multiple times by the CPE.

A Client Identifier (Option 1) is also present in the DHCPv6 transaction, optionally DNS recursive name server (Option 23) can be requested.