Re: [PLUG] OT: high speed internet connection

["William H. Magill" <magill@mcgillsociety.org>]

On 25 Jun, 2005, at 15:10, Jeff Abrahamson intoned:
> On Fri, Jun 24, 2005 at 09:26:00PM -0400, William H. Magill wrote:
>
> > However, note that while DCAnet offers "fixed" IP addresses, they no
> > longer offer Static IP addresses.  All new Fixed IP addresses are
> > permanently assigned to a MAC address, and served up via DHCP. The
> > only issue this raises is that of configuration. You really can't
> > configure everything yourself anymore, you have to use the DHCP
> > access so that your lease actually renews when it expires. (They use
> > a 7 day lease as I recall.) Since I've been a customer since the
> > beginning, I have a mix of both real static and fixed IP addresses...
> > as I've replaced hardware with a new MAC address, I've had to switch
> > over to the DHCP scheme. No big deal. It just works differently, but
> > the IP address doesn't change.
>
> What's the advantage to DCA of doing this, other than the fact that
> there's extra tech support when people upgrade machines and forget to
> reregister their new MAC address?

It's a scale and management issue.

DCA has always required that your MAC address be registered with  
their routers if you want your data to pass.

When DCA started DHCP was actually still a primitive set of software  
tools. Maintaining MAC mapped DHCP assigned addresses was just as  
labor intensive as manually maintaining DNS tables.  Over time, DHCP  
tools were improved and developed which both "scaled" (allowed for  
maintenance of much larger networks)  and were "easy to use."    
Similarly, what in the Telecom business is called "Operational  
Support Software" (OSS) was developed which had "buckets" to track  
things like MAC addresses and IP addresses, allowing meaningful  
databases to be developed which could be queried on a per client  
basis by someone without a PHD in SQL.

Today, it is simply "easier" to maintain one system -- DHCP -- for  
assigning and tracking already assigned IP addresses. That DHCP  
database is then fodder for the DNS environment rather than having to  
maintain both DHCP and DNS databases independently.

The other reason for MAC address assignment is what I alluded to in  
the first sentence -- it is both a protection against "spoofing" and  
a verification that you are who you claim to be. Because the routers  
are cognizant of what MAC addresses are permitted to present data on  
any given port, they can prevent "unauthorized" activity on that  
port. This is also tied into the issue of billing -- by preventing  
unregistered MAC addresses, it prevents services from being used  
which are not being paid for.  They don't care if you let a router  
spoof your registered MAC address and then allow that router to NAT a  
bunch of other machines -- that router is registered and being paid  
for... so if there is ever a problem, they have someone to come after.

T.T.F.N.
William H. Magill
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magill@mcgillsociety.org
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