[MLB-WIRELESS] [proposal] IP allocation

Kim Hawtin kim at aldigital.co.uk
Wed Nov 21 22:44:19 EST 2001

>   Kim> i worked for a large ISP in queensland and we had to reallocate
>   Kim> the IP address space because (we first used RIP,) the routing
>   Kim> was a nightmare... IP allocation on geography is a very tricky
>   Kim> thing to manage.
> that sounds like valuable experience Kim -- could you elaborate on the
> difficulties you faced?

we had a /19 ... which is huge for what we had in mind, but it is the smallest
IP space that the carriers would route to as it turns out.

our network was a classic star, then some of those ends points stared
out as well. 

the idea was to run RIPv2. RIP can export the the default gateway,
it can sumarise routes, and it hammers the network sending huge routing

i left the company before it changed over to OSPF, but if for any
reason a site went down, we could not dial (via ISDN) the site into
another further upstream router... because RIP could not do dynamic
reallocation, because everything was geographically allocated and

>   Kim> use the DNS namespace to determine geographic region.
> i think the use of DNS addresses a different goal.  the only reason to
> influence IP address allocation according to geography is to reduce
> the number of the routing prefixes that must be known by every router
> in the mesh.

i dont understand. why?


is this what you had in mind.


thats about as practial as you will get if your going for
a suburb type naming scheme... maybe you could merger the
melbcity and melbwireless bit ...

> putting geographic info in the DNS might be useful for other purposes,
> but won't help routing.

this is entirely true. this is where something like OSPF would work.
it is link state aware, ie it knows when a link goes down, then up  etc...
but getting people to adopt OSPF is rather a challenge.

i have had this argument with the consume folks and now with the 
*wireless groups in the US...

what some groups want to do is to have every node connected to the net
and use NAT to hide all the wireless nets, and run MobileIP for the
mobile nodes...

which is fine if its client access your after, to the internet.
but not if you want to provide and independent wireless
network that can route its own traffic and use the internet connection
to link remote wireless nets...

anyhow i am going to a talk tomorrow night on a new implementation of 
Mobile Mesh... i may have to buy the man a few pints to extract more
info yet =)

>   Kim> you need to find a solution that you can expand on later as
>   Kim> most people are reluctant to change their IP address once they
>   Kim> have implemented them.
> the only solution that will safely "expand later", IMO, is the use of
> IPv6 and a real, APNIC-allocated address space.

this is true, but extracting it may be a little difficult...

> by using IPv4 we are committing ourselves to NAT, to finicky selection
> of sub-range lengths, and a whole range of ongoing issues, at the
> benefit of simple current deployment.

you still have to manage the IP space properly, whether its IPv4 public
or private, or IPv6 ...



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