Subject: [mobile-ip] Coexistence with other uses for routing header

From: Charlie Perkins <[email-masked]>
Date: Tue, 04 Sep 2001 12:51:34 -0700

Hello folks,

In response to a question about how Mobile IPv6 uses routing
headers vs. other uses, I propose inserted the following paragraph
into the revised text, as the last paragraph of section 8.9.

Comments or additional clarifying text will be appreciated.

I put this as a SHOULD, because of the uncertainty about future
definitions of routing headers.

Regards,
Charlie P.

===========================================================================

It is possible that a correspondent node, having no knowledge of
the mobile node's care-of address, would still (for reasons unspecified
here but not necessarily related to mobility) attempt use a routing
header to deliver a packet to the mobile node's home address.
If the correspondent node accepts a Binding Update
and creates a Binding Cache entry for the mobile node, then
in that case, the correspondent node SHOULD put the mobile
node's care-of address as the last intermediate node address
of the routing header, following all other intermediate node
addresses that would have already been in the routing header
before the creation of the Binding Cache entry for the care-of
address.

---

From: Alper Yegin <[email-masked]>
Date: Wed, 5 Sep 2001 14:53:29 -0700 (PDT)

> Hello folks,
> 
> For the purposes of what to put into the revised specification,
> I think the main result of the recent discussion would be that
> the mobile node's home address does not have to be the last stop
> along the source route indicated in a routing header.  This part
> of the revision should not be the deciding factor in any
> specification about mobile routers or further route optimization,
> and so I have reformulated the paragraph as follows:
> 
>      It is possible that a correspondent node, having no knowledge of the
>      mobile node's care-of address, would still (for reasons unspecified
>      here but not necessarily related to mobility) attempt to deliver a 
>      packet, either to or by way of the mobile node's home address,
>      by using a routing header.  If the correspondent node subsequently
>      accepts a Binding Update and creates a Binding Cache entry for the
>      mobile node, then afterwards, the routing header used by the
>      corresponding node which includes the mobile node's home address
>      SHOULD also include the mobile node's care-of address.
>      The correspondent node SHOULD put the mobile node's care-of address
>      as the intermediate node address immediately preceding the
>      mobile node's home address.  When the care-of address is the
>      first intermediate node address, this implies that the care-of
>      address is to be placed in the Destination Address of the IPv6
>      headerd, and the mobile node's home address is the first entry
>      in the type 0 routing header.  Otherwise, the correspondent 
>      node MUST place the mobile node's home address immediately 
>      after the care-of address entry of the routing header, following
>      all other intermediate node addresses that would have
>      already been in the routing header before the creation
>      of the Binding Cache entry for the care-of address.
> 
> I hope this is better.

Yes, this looks good.

alper

---

From: Alper Yegin <[email-masked]>
Date: Thu, 6 Sep 2001 16:20:39 -0700 (PDT)

>  In your previous mail you wrote:
> 
> => yes but you should add something about the possible reversing
> of this by the receiver. This issue is easy to solve if it is MN
> but difficult if it is not. Has someone a simple proposal?

Francis,

I don't have a proposal, but just an observation: this just effects the reverse 
traffic not being route optimized (which is the case if this above method is not 
used anyways). And yes, mobile node can be smart about dealing with reversing 
routing headers...

alper

---

From: "Peter Grimstrup (TED)" <[email-masked]>
Date: Mon, 10 Sep 2001 15:33:34 +0200

Hi Charlie,

Some pieces of text for your consideration:

Peter

Charles E. Perkins wrote:
> 
> > Further I suggest changing section "8.9 Sending Packets to 
> a Mobile Node"
> > in a way that the next example will be described/allowed:
> > 
> > IPv6 Hdr:      source
> >                intermediate-dest-1
> > RH(4 entries): intermediate-dest-2
> >                CoA
> >                MN-HoA
> 
> No problem; can you suggest some text?

I think I prefer adding a small paragraph - the original contains the
mostly used instance:

8.9. Sending Packets to a Mobile Node

   ...
   entry.  For example, assuming use of a Type 0 Routing header [6], if
   no other use of a Routing header is involved in the routing of this
   packet, the mobile node sets the fields in the packet's IPv6 header
   and Routing header as follows:

    -  The Destination Address in the packet's IPv6 header is set to
       the mobile node's care-of address copied from the Binding Cache
       entry.

    -  The Routing header is initialized to contain a single route
       segment, with an Address of the mobile node's home address (the
       original destination address to which the packet was being sent).

   If a Type 0 Routing Header [6] is used (for some other reason than
   mobility), the Home Address of the Mobile Node will be the last entry
   immediately preceded by the Care-of Address of the Mobile Node.

   Following the definition of a Type 0 Routing header [6], this packet
   ...

For the sake of completeness, I suggest a (new) section:

(8.10. Combining Binding Cache Entries and a Type 0 Routing Header)

   If a node for some reason not specified in section 8.9 is using a
   Type 0 Routing Header, the list of addresses found in the routing
   header including the first address found in the IPv6 header SHOULD be
   matched against the content of the Binding Cache. If match(es) are
   found, the appropriate Care-of Address SHOULD be inserted immediately
   before the matching address, thus expanding the Routing Header as
   needed.

Shouldn't section "10.3. Receiving Packets While Away from Home"
have a new subsection (before last subsection) something like:

   If the home address is not the last segment of the routing header,
   i.e. this node is just an intermediate on the path to the final
   destination, the usual processing of the routing header SHOULD be
   executed, which will result in the packet being forwarded to the next
   (intermediate) destination.