Subject: about draft-pashby-ipv6-network-discovery-00.txt

From: Francis Dupont <[email-masked]>
Date: Tue, 02 Aug 2005 15:55:13 +0200

Network discovery is a well known unsolved problem in IPv6.
I believe the issue was described by Jean-Luc Richier at least 8 years
ago... The previous proposed solution is based in ICMP info lookups:
 1- routers' MIB are read to find next hops
 2- link-local addresses of next hops are translated to usuable
    global addresses using an ICMP info lookup proxy service
 3- goto 1

[email-masked]

PS: BTW the proxy service uses ICMP on the link, cf security considerations
of ICMP infos, discussion about draft-ietf-ipngwg-icmp-name-lookups-12.txt

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From: Pekka Savola <[email-masked]>
Date: Tue, 2 Aug 2005 16:59:17 +0300 (EEST)

> Network discovery is a well known unsolved problem in IPv6.

Isn't that a good thing, so it can't be used for mapping the network?

In this case, the "cure" appears worse than the disease.

My own first idea of the solution for this problem would be defining 
an appropriately-scoped multicast address(es) to which you'd send an 
echo request to.

-- 
Pekka Savola                 "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings

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From: Francis Dupont <[email-masked]>
Date: Tue, 02 Aug 2005 16:09:04 +0200

In your previous mail you wrote:

   
=> perhaps but don't forget you can't map your own network (:-).

=> the cure needs access to some services (SNMP and ICMP name lookup
proxy services) which are supposed to be protected even by the
stupid manager (in fact, they are by default closed).

=> do we want network discovery (so it is enough to get routers and
their route tables) or node discovery (in this case multicasted echo
requests are necessary)?

Regards

PS: note both proposals are based on ICMP name lookups in order to
get rid of the basic issue: link-local addresses are not useful when
you are not on the link.

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From: Pekka Savola <[email-masked]>
Date: Tue, 2 Aug 2005 17:32:53 +0300 (EEST)

> their route tables) or node discovery (in this case multicasted echo

Either way is fine with me; either have the routers, the hosts, or 
both join the multicast group.

> get rid of the basic issue: link-local addresses are not useful when

Sure, and this problem wouldn't exist with the multicast approach, as 
the source address that the hosts would pick in the responses would be 
global/ULA.

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From: Francis Dupont <[email-masked]>
Date: Tue, 02 Aug 2005 16:50:09 +0200

=> I disagree: the problem still exists but in a different form: to make
a network map/topology you need to bind link-local and global addresses.

Regards

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From: "Gunter Van de Velde (gvandeve)" <[email-masked]>
Date: Tue, 02 Aug 2005 17:04:34 +0200

<snip>
>a network map/topology you need to bind link-local and global addresses.
<end snip>

Not sure. Why do you assume that the global address tells you anything about
location? It would be better to have something that maps identities of devices
and at his turn potentially maps it into some kind of topologies.

It would be interesting however to have awareness of who is attached
and with which addresses (a use example would be for ISP billing purposes).
There are techniques out there that allow this to be done, but i doubt if 
we need
a protocol for this purpose as such.

Groetjes,
G/

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From: Francis Dupont <[email-masked]>
Date: Tue, 02 Aug 2005 18:13:41 +0200

<end snip>
   
   location?

=> it doesn't tell anything about location, it tells something about routers
and their routes. Don't forget that IGPs fully work with link-local
addresses only.

   It would be better to have something that maps identities of devices
   and at his turn potentially maps it into some kind of topologies.
   
=> you can't query a router if you have only its link-local address(es)
and you are not on (one of) its link(s).

=> and legal requirements for ISPs in Europe.

   There are techniques out there that allow this to be done, but i doubt if 
   we need a protocol for this purpose as such.
   
=> network discovery is not for ISPs (if your ISP needs it, I suggest
to change for another one)... It is for the poor new network manager
who has only far from up to date maps of his network and needs to
fix it Friday evening.

Regards