Subject: Source Address Selection just from Routing Information

From: FUJIKAWA Kenji <[email-masked]>
Date: Fri, 30 Nov 2007 11:56:58 +0900

Hi all,

In http://www3.ietf.org/proceedings/07dec/agenda/6man.txt ,
> - Address Selection
>      * draft-fujikawa-ipv6-src-addr-selection-01.txt   Fujikawa       5 minutes
my slot is allocated.
Thank you very much for allocation, Chairs.

I would like to briefly introduce my draft.

The question of this drafts is that
is there a way to select a appropriate source address
just from traditional routing information when multihoming?

In my draft, one method to select a source address
just from routing information, i.e. traditional routing tables
of which entries consists of a pair of destination and next hop.
This method requires a brief implementation modification and
appropriate management of a network.

The following is an examle.

                        +---+
                        |CN |
                        +-+-+
                          | 2001:db8:2001::CN
                          |
                      +---+---+2001:db8:2000:/36
                      |       |
            +---------+ ISP2  |
            |         |       |
            |         +-------+
            |
        +---+---+2001:db8:1000:/36  +-------+2001:db8:3000::/36
        |       |                   |       |
        | ISP1  +-------------------+ ISP3  |
        |       |                   |       |
        +---+---+                   +---+---+
            |                           |
            |                           |
            +------------+ +------------+
          2001:db8:1000:R| |2001:db8:3000:R
                        ++-++
      2001:db8:1001::/48| R |2001:db8:3001::/48
                        +-+-+
        2001:db8:1001:1:R | 2001:db8:3001:1:R   <- The main different point 
                          |                        wrt management
       2001:db8:1001:1:EN | 2001:db8:3001:1:EN
                        +-+-+
                        |EN |
                        +---+

     Routing Tables:
       R:
       Destination         Next Hop
       2001:db8:1000::/36  address_of_ISP1's_router
       2001:db8:2000::/36  address_of_ISP1's_router
       2001:db8:3000::/36  address_of_ISP3's_router
       EN:
       Destination         Next Hop
       2001:db8:1000::/36  2001:db8:1001:1:R
       2001:db8:2000::/36  2001:db8:1001:1:R
       2001:db8:3000::/36  2001:db8:3001:1:R

Management Issues:

The downstream interface of router R is assigned both addresses
2001:db8:1001:R and 2001:db8:3001:R.
This is required even if R has only a single downstream link.

Each of R and EN keeps the routing table shown in Fig. 2, respectively.
The next hop becomes different according to a destination
address, even when a single upstream router exists.

Implementation issue:

When an entry of a routing table is hit, a source address is selected
which longest-matches the next hop in the entry.

In the above example, on end node EN, when the entry 
"2001:db8:2000::/36  2001:db8:1001:1:R" is hit 
for the destination "2001:db8:2001::CN",
the next hop becomes "2001:db8:1001::R", as a result, the address
"2001:db8:1001:1:EN" is selected, because it longest-matches the next hop.

I suggest a method to select the longest-matching address to the next hop
should be added as one of the source-address-selecting methods.
------------------------------------------------------------------
FUJIKAWA Kenji(Ph. D.) ROOT Inc., Osaka Information Laboratory
Pias Tower 5F, 3-19-3 Toyosaki Kita-ku, Osaka, 531-0072, Japan
Mail:  [email-masked], [email-masked]
WWW:   http://www23.atwiki.jp/hudikaha/
Skype: fujikawakenji
Tel:   +66-8-4773-3252

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