[MLB-WIRELESS] IP Addressing

[Adrian Close]

On Mon, 8 Apr 2002, ABBENHUYS, Ryan wrote:

> I'm thinking it might be good to stay out of the Class C range simply due to
> the fact that a lot of people use this on their own internal networks.  And
> who knows we may even outgrow the range.  So that leaves us with the Class A

Unlikely with a sensible allocation policy.  A Class B is a lot of
addresses (192.168.0.0/16 is a Class B).

>  Lilydale       NodeBDJ: 203.30.83.120/29
>  Warranwood     NodeBEA?: 203.30.83.48/28

These are my nodes, running with addresses allocated from the netblock
routed to my Telstra link.

>  Warrandyte     NodeDIH: 203.44.46.128/26

This is out of a Telstra netblock, many bits of which are allocated to
Telstra customers.  I'd guess these are the globally routable addresses
routed to node DIH.

> And NodeBCG worries me just because it's the 192.168.*.* range which is of
> course common on home LAN's.

Bingo.  The same problem exists with any of the RFC1918 space.  As long as
we make sure no two nodes on the network use the same range, this is fine
(incidentally, this is of course the purpose of having globally unique
allocations).  The key is co-ordination, which seems to be happening.

If it happens that two nodes _do_ choose the same range, then either
someone renumbers, does some ugly NAT thing or just doesn't communicate.

> And i beg of you, please don't bring up IPv6 or the issue of an Internet
> routable address range because I warn you now I WILL resort to abuse,
> namecalling, jokes about your mother etc.  And no I am not kidding.

IPv6 has a go at some of the allocation/conflict issues by having scoped
addresses.  There are link-local addresses, site-local addresses and
global addresses.  Link local addresses are simply _not_relevant_ outside
the context of the link in question (e.g. an Ethernet broadcast domain, a
PPP link or whatever).  Site local addresses are relevant with the "site",
whatever that is...  The Brisbane Mesh people had some discussion on this
if you're at all interested.  >;-Q

Incidentally, there should be no problem having a mix of RFC1918 and
"real" addresses on our eventual MAN.  They're all just addresses, after
all, and will happily co-exist in routing tables.

Pick something that isn't in use.  Be prepared to renumber at some point.

Adrian Close			email:	adrian at close.wattle.id.au
1 Old Gippsland Rd.		web:	http://www.close.wattle.id.au/~adrian
Lilydale, VIC, 3140, Australia	mobile:	+61 412 385 201


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