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FAQ - Why Is the Length of an IPv6 Interface ID 64 Bits and How Is the ID Generated

Publication Date:  2013-09-25 Views:  117 Downloads:  0
Issue Description
Why is the length of an IPv6 interface ID 64 bits? How is the ID generated?
Handling Process

The 64-bit IPv6 interface ID is used to map MAC addresses in different LAN technologies. A 64-bit IPv6 interface ID can map an Ethernet 48-bit MAC address, IEEE 1394 compliant 64-bit MAC address, and future new MAC address.

An IPv6 interface ID may be originated from: 

1. An IEEE-defined EUI-64. An EUI-64 address can be sourced from an IEEE 802 address and allocated to a network adapter. This is the default IPv6 interface ID generation mode for Windows XP.

For example, ME60 V600R005C00SPC500 in PPPoE dialing mode can instruct a terminal to obtain an IPv6 interface ID in EUI-64 mode:

domain grape//Enter the domain.

ipv6 ppp assign-interfaceid //Without this command line, the terminal uses a randomly generated interface ID by default.

2. A temporary interface ID randomly generated and allocated according to the MD5 hash algorithm defined in RFC4941

3. DHCPv6 allocation

For example, ME60 V600R005C00SPC500 in IPOE mode can configure IPv6 interface IDs to be allocated by IPv6cp negotiation.
domain grape
//Enter the domain.
ipv6 nd autoconfig managed-address-flag interface-id ipv6cp //Configure the ipv6cp to negotiate interface IDs.

4. Link layer address, sequential number, randomly generated ID in PPP interface configuration according to RFC5702

5. Manually configured ID

6. Permanent interface ID, which is randomly generated to release the unicast IPv6 address scanning load in a subnet. You can run the netsh interface ipv6 set global randomizeidentifiers=disabled command in OS, such as windows vista to disable the permanent interface ID. 
Root Cause