Re: [dhcwg] Fw: Assigning IPv4-compatible IPv6 addresses via DHCPv6server

["Bernie Volz (volz)" <[e-mail]>]

Are you asking about this as a general question or regarding a specific
server?

 

For Cisco Network Registrar's DHCP (DHCPv6) server, as the low 32-bits
of the IPv6 address are the IPv4 address and if you don't really care to
do anything special, you could probably define a prefix that has a /120
range (for a /24 IPv4 subnet) [or /112 for a /16, ...) and the server
would then allocate the IPv6 addresses. CNR just doesn't care what
prefixes you define (it is perfectly happy with assigning addresses out
of a 0::a01:200/120 prefix if you wanted to assign 10.1.2.0/24 addresses
- you can even enter this as ::10.1.2.0/120 - you might have to take
some special actions to avoid assigning the all-zero's and all-one's
addresses - such as by creating garbage reservations for those
addresses).

 

Or, if you want more intelligence, you could do this if you wrote an
extension that did the allocation of the IPv6 address.

 

But there is no specific/special support for IPv4 compatible IPv6
addresses. 

 

I suspect that other DHCPv6 servers could be configured to assign these
addresses as well?

 

Note that RFC 4291 deprecates these addresses:

 

   The "IPv4-Compatible IPv6 address" is now deprecated because the

   current IPv6 transition mechanisms no longer use these addresses.

   New or updated implementations are not required to support this

   address type.

 

-          Bernie

 

From: [e-mail] [mailto:[e-mail]] On Behalf
Of [e-mail]
Sent: Wednesday, March 09, 2011 9:19 PM
To: [e-mail]
Cc: [e-mail]
Subject: Re: [dhcwg] Fw: Assigning IPv4-compatible IPv6 addresses via
DHCPv6server

 


I am trying to configure DHCPv6 server to assign IPv4-compatible IPv6
addresses for dual stack hosts. The server must be configured by
administrator with IPv6 prefix. The generated IPv6 addresses must be
created like :

IPv6_prefix + IPv4_address+........

Is that possible to make DHCPv6 server capable to do that without
configuring DHCPv6 clients? 

------------------------------------------------------------------------
------------------------------------------------ 

Hi,Robert 

    IPv4-compatible IPv6 addresses take the form ::/96+IPv4
address/32,they are only used to dynamically tunnel IPv6 packets over
IPv4 networks(Automatic tunnel).In windows os,it is created by a
command: netsh interface ipv6 set state v4compat=enabled,and it is
generated by the IPv4 address of the host. 
    So, I dont kown if you are talking about this ? Maybe you are
talking about IPv4-mapped IPv6 address,then the IPv6_prefix would not be
fixed,and the client would not recognize it if you didnt configure
anything.But which OS support this? 

Regards 
     

 
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