Marlon says:

How many ip addys does each customer need in a fully routed network?

* One!

gateway, ip and broadcast.  I see that as three.  Or does a /30 use up four?

* That depends on how many clients you have off that AP. I generally use a
/24 at each tower - or a group of smaller towers. Then all clients off those
towers share a mutual broadcast and gateway IP.

Either way, by bridging each customer only needs one.

* Same as a routed network.

The benefits that come with routing to each customer can be made up for by 
using a router and/or firewall at each cpe and by blocking client to client 
communications.  Both this and routing result in the same thing eh? 
Customers don't mess with the other customers or the network.

* Even in a routed network clients on the same /24 can see one another
unless you kill the intra bss ability. Depending on the amount of private
IPs you are doing NAT on and where you do it - -I can NAT everyone on my
network or just each /24 with 1 public IP that is a part of a /24, /29 /27
...etc   Its really no waste if done in this fashion.



----- Original Message ----- 
From: "Brad Belton" <[EMAIL PROTECTED]>
To: "'WISPA General List'" <>
Sent: Saturday, December 02, 2006 8:57 PM
Subject: RE: [WISPA] 900 Mhz Mikrotik SR9 Clients

Hello Marlon,

How do you figure a residential client (or any client for that matter) ties
up three IPs?  I can see four IPs (/30) or simply one IP out of a larger
subnet dedicated to the sector.

We typically assign a /29, /28 or /27 to a Trango 60* sector and assign one
public IP to each CPE router.  The radios get private space to conserve
public IP space as well as increase security.

IMO, each client deserves one public IP for a variety of reasons.  Two come
quickly to mind.

First, if a client becomes infected with a SPAM virus he'll only get himself
"blacklisted" and not a bunch of clients that happen to also be NAT'd behind
the same IP address.  Second, even a basic cable modem client gets one
public IP address.  No reason to give the cable guy a leg up over your
service over one IP!



-----Original Message-----
Behalf Of Marlon K. Schafer
Sent: Saturday, December 02, 2006 10:36 PM
To: WISPA General List
Subject: Re: [WISPA] 900 Mhz Mikrotik SR9 Clients

----- Original Message ----- 
From: "Butch Evans" <[EMAIL PROTECTED]>
To: "WISPA General List" <>
Sent: Saturday, December 02, 2006 11:51 AM
Subject: Re: [WISPA] 900 Mhz Mikrotik SR9 Clients

> On Sat, 2 Dec 2006, Marlon K. Schafer wrote:
>>Yeah, the waters in the routed vs. bridged argument are getting more and
>>more muddied all of the time.
>>How many wasted ip's are there in a routed network?  Lots.
> This is a big misconception.  I don't have time to go into it here,
> but the truth of the matter is that what you are calling "wasted" is
> better described as a "cost" in exchange for a benefit.

It's a very high cost.  Why does every residential user need to tie up 3 ip
addys?  How long can we keep handing them out like that before we run into
trouble again?  There is only so much nat that we're gonna get away with.

>>What are the benefits of a routed network?  More control and better
>>customer isolation.
> This is only one of the benefits.  Scalability especially in a wireless
> network is a benefit.  Alvarion offering VLAN will provide some of the
> scalability and other benefits that routing will offer. If you think that
> VLANs are a "scalable" solution, look over the networks owned by the tier
> 1 providers and see what they are using...routed with BGP.
>>With the new ap's that block client to client isolation, with vlan
>>switches, bandwidth controlling cpe (or other solutions) and features like

>>what Patrick is talking about routing is becoming less and less critical
>>every day.
>'s becoming less and less used toward the customer because more and

> more people are getting into the business of providing internet service
> without understanding HOW or WHY their network would function better if it

> were not bridged.  You can argue that point if you want, but I have moved
> more networks from bridged to routed with positive results than the other
> way around.  (there is one notable exception, but I think those results
> are a bit skewed for other reasons.)
> Is bridging "easier"?  Yes.  Is it common?  Among smaller providers, yes.
> Is is scalable?  Only if you use some other technology (such as vlan) to
> create the separation between the endpoints.  As I said, even with VLANs,
> there is a limit to the scale the network can reach without some routing.
>>solution.  They vlan customers into a single port to the isp. Basically
>>frame a fancy switch, almost frame relay.  No routing used at all.  We
>>don't even have a good option for routing at the
> You don't think their networks are routed?   Look at your border
> router...the public interface is going to have a /30 address...your range
> of public IP space is routed via that /30 address.  You are incorrect in
> your assumption that there is "no routing used at all".

On the client side that's not correct.  We have ONE vlan port.  ALL of our
fiber customers connect right in to that vlan.  That vlan hits a switch on
our network, right beside one of the main wireless links.  No routing till
it hits the customer's site.

>>customer other than doing it just because.  It's certainly not a
> No...not a requirement.  It's just a more scalable solution.

There are nearly 4000 (unfortunately not all mine :-) 100meg customers on
that network.

>>Maybe if you are a HUGE isp but certainly not for a few hundreds subs.
>>Hundreds of subs it's still a maybe.  And with thousands
> I'd disagree here, too.  But, I've only been an ISP since 1993, so what do

> I know...


>>The technology included in the VL line makes it easier to build a network
>>that can be run by less technical staff.  There is a cost savings there
> It is true that the VL line of products offer some real options. VLANs are

> a GOOD tool, and having this option DOES offer some cool upsale
> possibilities.  But, VLANs are not intended to be a replacement for a
> routed network.  I've been in this business for a long time.  I've built
> several networks to fairly large scale, including more than one to over
> 1000 customer base.  One that I am now managing has over 3000 subs.  That
> network is using VLANs to provide some services.  It is using other
> technologies as well, but the network is routed.  You can't scale a
> bridged network.  It's just that simple.  As I said in another post..."you

> don't have to believe that, others don't have to do it, but it IS the best

> practice".

I'm just saying that it's far less important than it used to be.  Shoot, you

know my network.  I've even gone so far as to split it into two halves with
different upstreams.

And what did the average customer see when that happened?  Nothing.  Well
the ones in Odessa got 10 megs of service to the ap rather than 1.5, but
other than that, no noticable change.

> -- 
> Butch Evans
> Network Engineering and Security Consulting
> 573-276-2879
> Mikrotik Certified Consultant
> (
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