From: Howard C. Berkowitz (hcb@gettcomm.com)
Date: Mon Jun 21 2004 - 23:58:26 GMT-3
At 10:29 PM -0400 6/21/04, Scott Morris wrote:
>So, then it's true... It was designed to give "Lack of Subnetting for
>Dummies" a run for its money!
Well, yes. Certainly VLSM.
>I just don't get why people can't handle NAT
>and subnetting in the v4 space, which is nice enough to work in decimal
>renditions, and yet they think it is a great idea to give buttloads of
>addresses to people, but do it in a hexadecimal format... Which is, of
>course, MUCH simpler to deal with.
I never found it such, but I came to dotted decimal after 12-15 years
of working in binary, octal, and hex as well as decimal. When I
introduce IP, I always start in binary until people have the idea of
counting bits from the left. I then introduce dotted decimal as a
notation, and, regretfully, mention classfulness only as late as
possible.
>
>Oh yeah, and don't forget that :: thing too! This will bring IP to the
>masses? Come on.
It's not intended, in the slightest, to make it easier for the masses
to do addressing by hand. It is intended to let computers do a great
deal of address administration that now has to be done manually.
Admittedly, too many people make their IPv4 hard to use by not making
enough use of DNS, DHCP, and linkage between them.
It's also designed to work better with purpose-built
hardware/ASICs/microcode, than IPv4. IPv4 is easy enough to program,
but not machine-efficient in doing things like quickly parsing the
options fields.
>
>Mathematically, it's all workable, and I don't have a problem with the
>technical end... I just believe it was designed for a set of bad reasons,
>and bad philosophy doesn't make good policy.
>
>Ah well, enough rant for me. :)
>
>Scott (who believes IPv6 is Evil and was most likely designed by Saddam
>Hussein and/or Adolf Hitler)
Not Bill Gates?
>
>-----Original Message-----
>From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
>Howard C. Berkowitz
>Sent: Monday, June 21, 2004 9:10 PM
>To: ccielab@groupstudy.com; security@groupstudy.com
>Subject: IPv6 for Scott Morris
>
>At 8:29 PM -0400 6/21/04, Scott Morris wrote:
>>
>>
>>Let's move on to other important things like why IPv6 should be dropped
>>from the face of the Earth and never be used on a CCIE exam, let alone
>>a real network
>
>Let me say that I support the use of IPv6, and indeed take some of the
>blame; I was in the plenary meeting at the Toronto IETF that made the final
>decision on IPng (among the several candidates). That being said, I see a
>great many proposals for using IPv6 to be made for very bad reasons. There
>are also some unsolved problems with IPv6 implementation, especially in
>multihoming, but also in architectural indecisiveness in separating -- or
>not separating -- the functions of locator and identifier.
>
>There are still a lot of people that believe the reason for going to the
>128-bit address space was to have enough room to give a static address to
>every insect. Expanding the static address space, in fact, was one of the
>non-goals of IPv6 design.
>
>IPv6 consciously, deliberately wastes space in the address field.
>This was done, in large part, to avoid the gyrations one goes through in
>figuring out how much of a prefix can be summarized. Much of the
>IPv6 address space is as-yet unallocated, but such things as the unicast
>public address space is designed to be principally fixed-field. The format
>ID bits at the start of the address give the format of the rest, but in a
>way far more flexible than the four bits used in IPv4 classful addressing.
>
>Why have fixed-length TLAs and NLAs (and yes, there are nuances of splitting
>the NLA)? The simple answer is to make it simple to change providers.
>People are generally aware of there being two mechanisms to get the
>low-order part of a station's addres: stateful DHCPv6 and stateless
>autoconfiguration. In stateless autoconfiguration, end stations learn the
>high-order part of their address from the local router.
>
>What is more of a mystery is how the _routers_ learn the high-order address.
>While they can, of course, be statically configured, the
>IPv6 suite includes a Router Renumbering Protocol by which a router can
>dynamically learn the TLA/NLA. Typically, SLAs will be partially manually
>configured (much like OSPF or ISIS areas).
>
>In an ideal scenario, let's say you change ISPs, and you are using
>provider-assigned address space that is supposed to change. In IPv4, this
>can be quite painful, depending on how well you have prepared your hosts --
>but there are really no good and general mechanisms to renumber your routers
>and figure out your new external prefix.
>Believe me, I tried -- I wrote
>http://www.isi.edu/in-notes/rfc2072.txt , the "IPv4 Router Renumbering
>Guide".
>
>But in the IPv6 world, your external router activates a connection to an ISP
>router, and the enterprise router plaintively asks, in IPv6 Router
>Renumbering Protocol, "who am I?" The provider router, assuming it speaks
>this protocol, will respond, securely, with the new high-order bits of the
>address (basically TLA and NLA for enterprises). Your external edge routers
>now propagate this new prefix into hierarchically lower routers, which pick
>up SLA bits as the information propagates downward. Eventually, everything
>above the end station identifier is floating around edge LANs in Router
>Advertisement packets (ICMPv6).
>
>An end station can then concatenate this prefix to its MAC address or other
>locally significant identifier, and, BANG -- it's addressed.
>Good practice would have it register the address with Dynamic DNS.
>
>Meanwhile, if you have hosts that don't need direct external connectivity,
>they are happily going along in the site-local space (i.e., IPv6's
>equivalent to RFC 1918). It may be that the only things that really need to
>get new prefixes are the outside addresses of your firewalls and external
>router.
>
>Depending on the specific design, you may indeed be able to avoid overloaded
>NAT and go one-to-one with provider addresses. This isn't such a strain on
>your provider if they can just aggregate the SLA and below in their customer
>edge routers, so they only need to advertise TLA and NLA, or, in large
>providers, TLA alone, to the rest of the world.
>
>Do note that we are still experimenting with how to grow the Internet. While
>the CIDR assumption has been provider-based aggregation, IPv6 architecture
>consciously allows for assigning TLA's and/or NLA's to geographical exchange
>points, thus allowing for geographical as well as provider-based
>aggregation.
>
>There are other reasons for IPv6, but I wanted to touch on some of the ones
>I find are least well understood.
>
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