Subject: (ngtrans) Designing IPv6 network guidelines?

From: Pekka Savola <[email-masked]>
Date: Thu, 22 Feb 2001 00:07:56 +0200 (EET)

Hello all,

I hope this is the right forum for this; if not, please tell what would be
a more proper channel.

I've been looking for information on how you should design your IPv6
network topology and concerning issues.  There's good information about
different technical solutions, but not so much information about suggested
approaches/pros/cons etc.  Pointers would be appreciated (I think I've
gone through most RFCs and drafts at some level).

In generic terms, I'm looking for some "best known practices" or other
guidelines for how IPv6 should be taken into use in a slightly larger
environment, e.g.

 * What kind of network prefixes should be allocated?  When
should you use /48 and when /64 (e.g. LAN segment?)?  What to do when /64
(or /48) is too little but the next level too much?
 * Should you allocate some service aliases e.g. xxxx:yyyy:zzzz::1 always
to be a router, ::2 DNS etc. -- is this a good approach?
 * Is routing between 6bone and production addresses in use/reliable yet?
Does 6to4 work in practise?  Are there 6to4 prefixes being announced to
the net at large? (Looking for a setup where IPv6 enabled LAN segments
would connect via ipv6 enabled gateways to a central IPv6 router, from
which would provide the connectivity)
 * DNS.  How do you manage e.g. reverse records easily.  How do you manage
changing interface addresses easily.

Other issues:

1) Some RFC recommended using site-local addresses for point to point
links.  Won't this break traceroute?

2) Some seem to use /126, others /64 for point-to-point interfaces or the
like.  Recommendations?

3) RIRs are allocating /35 prefixes for ISPs and the like.  Organisations
get a /48 from them.

Now, let's take an example about how academic networks in North Europe are
built (rough estimate):
 * a country-wide operator entitled to a /35
  * university or the like which would get (some?) /48's
   * depertment which would get a /48 [?] or multiple /64
    * lab or LAN's which might get multiple /64's

I read from www.jp.ipv6forum.com that ISP's should allocate /48's to
households etc.  I fail to see how /35 wouldn't run out very quickly (It
_is_ only 8096 addresses) with this practice.  Also, as demonstrated from
the above, if you have several organisatorial levels, it might be
difficult to design a clean network if only elements you can use are /35,
/48 and /64.

Please Cc:, as I'm not on the list.  Thanks.

-- 
Pekka Savola                  "Tell me of difficulties surmounted,
Netcore Oy                    not those you stumble over and fall"
Systems. Networks. Security.   -- Robert Jordan: A Crown of Swords