Subject: Re: May one configure IID= "0" for an address ?

From: [email-masked]
Date: Mon, 5 May 2003 10:12:11 +0200

Bob,
Thanks for your reply.
It is pretty much clear: "normal" unicast addresses must keep off from
IID=0.

Robert

Bob Hinden <[email-masked]> on 30/04/2003 19:27:56

To:    Robert PESCHI/BE/ALCATEL@ALCATEL
cc:    [email-masked]
Subject:    Re: May one configure IID= "0" for an address ?

Robert,

At 05:14 AM 4/30/2003, [email-masked] wrote:
>Hi,
>I have found nowhere in (draft)-RFCs a restriction on the value
>an Interface ID can take. So in principle any values in [0, 2**64-1] could
>be configured as IID for an IPv6 address.

Zero is a legitimate address for any field in an IPv6 address.

>However, RFC 3513, section 2.6.1 defines the "Subnet-Router Anycast
>address" as being <subnet prefix>::

As you noted that RFC3513 (and it's predecessors) defines the
"subnet=router anycast address" as any prefix with the remaining bits of
the address set to zero.

>Does that mean that configuring  IID = 0 might interfere or conflict with
>some anycast mechanism ? and consequently that configuring IID=0
>for an address should be avoided ? ...or what do I miss there ?

Using a IID of zero does conflict with the subnet anycast address.  So zero
IID's are legal, but are reserved for the "subnet=router anycast address".

Does that help?

Bob

--------------------------------------------------------------------
IETF IPng Working Group Mailing List
IPng Home Page:                      http://playground.sun.com/ipng
FTP archive:                      ftp://playground.sun.com/pub/ipng
Direct all administrative requests to [email-masked]
--------------------------------------------------------------------