Re: Default address used

On Thu, 2005-11-24 at 13:29 -0500, Jason Gauthier wrote:
> Well I was capturing TCP/IP packets because we found an Apache server
> working over IPv6.

Would you mind describing in a bit greater detail what you found, and
how your attempt was made? Such as, how did you try to connect to the
Apache server (via a DNS name or a literal address?), is the Apache
server on the same link, and so on?

Fredrik Tolf

> On 11/24/05, Fredrik Tolf <[email protected]> wrote: 
>         On Wed, 2005-11-23 at 22:25 -0500, Jason Gauthier wrote:
>         > Well I mean, what's the use of having an IPv6 address if you
>         can just 
>         > use your local link address?
>         > There must be something I still don't understand.
>         
>         The point is that the link-local address can only (as the name
>         implies)
>         be used on the local link. Routers are forbidden to route it
>         beyond the 
>         same physical link network.
>         
>         Therefore, it is often used when talking to other nodes on the
>         same
>         physical link (especially when another link-local address is
>         used as the
>         destination address). When talking to nodes on other links, an
>         address 
>         with larger scope is used.
>         
>         What kind of packets is it that you are capturing? Surely, the
>         link-local address isn't used if you try to contact an outside
>         host,
>         such as www.ipv6.org?
>         
>         Fredrik Tolf
>         
>         > On 11/23/05, Fredrik Tolf <[email protected]> wrote:
>         >         On Wed, 2005-11-23 at 12:15 -0500, Jason Gauthier
>         wrote:
>         >         > When I capture packets on Windows XP and that I've
>         set up an 
>         >         IPv6
>         >         > address with a DHCP server, the capture says the
>         request is
>         >         from the
>         >         > default address that we can't delete on Windows
>         XP.
>         >
>         >         By "default address", do you mean the fe80::*
>         link-local 
>         >         address?
>         >
>         >         > Any idea how I could delete it or change the
>         default address
>         >         to use?
>         >
>         >         You cannot delete the link-local address, since the
>         IPv6
>         >         specification
>         >         requires that every node has one. As for the source
>         address to
>         >         use for
>         >         any given packet, that is decided depending on the
>         destination
>         >         address 
>         >         according to RFC 3484.
>         >
>         >         According to RFC 3484, it is possible to make a
>         certain
>         >         address
>         >         "preferred" for being used as source address, but
>         even so, an 
>         >         address is
>         >         only tested for being preferred once it has been
>         selected as a
>         >         candidate
>         >         after being tested for scope similarity. See section
>         3.1 of
>         >         RFC 3484 for 
>         >         the definition of address scopes.
>         >
>         >         > I really need him to make requests from the DHCP
>         address
>         >         given.
>         >
>         >         Thence comes the real question: Why would you want
>         that? 
>         >
>         >         Fredrik Tolf
>         >
>         >
>         >
>         
> 

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