Can a router be a router and an access point at the same time?

Have a question or want to start a discussion? Post it! No Registration Necessary.  Now with pictures!

Threaded View
Googling for how to set up my home broadband router to allow a far-away  
connection, I'm confused by the term "access point".

My home broadband wireless router is typical in that it *is* the access  
point for all my home PCs and cellphones on WiFi.  

But, when I google how to set up a far-away antenna (Ubiquity Bullet M2  
with a planar antenna) from a half mile away to connect to my router, I  
immediately become confused.

A router, by default, *is* an access point. So why would I have to set it  
up *as* an access point?  

NOTE: All I want to do is aim the Bullet M2 at my router to connect from  
a half mile away. Do I set up the bullet as a "router" or "bridge"?


Re: Can a router be a router and an access point at the same time?
Quoted text here. Click to load it

By the usual definition, a "router" is a device which is connected to
two or more different IP networks.  A typical "home use" WiFi
AP/router is connected to two IP networks - one network is the ISP
network, and the other network is the home network.

The "access point" functionality, per se, is not a router.  Rather,
it's a "bridge".  It's connecting two physically different network
segments (e.g. an Ethernet, and a WiFi radio network) which are both
part of the same IP network (in a home this is usually an IPv4
"private" network, in the 192.168.xx.yy network number space).

There are many devices which are routers (e.g. have multiple Ethernet
ports bound to different IP networks) and which are not access points
(i.e. they have no WiFi radio at all).

In a typical home network, a "one-box" device (e.g. the classic
Linksys WRT54G or similar) is usually performing multiple functions:

-  It's acting as a WiFi access point
-  It's bridging the WiFi LAN into the home's Ethernet LAN
-  It's acting as a DHCP server, handing out IP addresses on the LAN
   to client devices (both wired and wireless)
-  It's acting as a client system on the ISP's WAN network (cable or
   DSL or ??) - sometimes with a fixed IP address, sometimes with
   a dynamic IP address assigned via DHCP, sometimes as a PPP-over-
   Ethernet or PPP-over-ATM client.
-  It's acting as a router (and, frequently, a "network address
   translator" and/or proxy) between the wired/wireless LAN, and the
   WAN (Internet).

You don't have to use all of these functions at the same time.

For example, in my own home, I have a separate firewall/router/server
system (a Linux box with multiple wired Ethernet ports) which
performs the routing, network address translation, and DHCP-
server jobs.  I don't need my WiFi box to perform any of these.  So, I
simply disable the routing and DHCP-server functions, and use
the WRT54GS or equivalent as an access point.

In the case of trying to set up a remote node which talks to your home
network (e.g. an Ubiquity) you have a number of choices as to how to
go about it.  In some cases, if you have only one (wired) client
device attached to the Ubiquity, you can use the Ubiquity as a "client
bridge" (you'll sometimes hear these referred to as "gaming adapters"
because that's how they are often used).  The remote client device
will, in effect, be on a simple remote extension to your home's LAN,
and it will receive an IP address assigned by your main router/AP's
DHCP server.

It's tricky to try to attach multiple remote clients to a single
"client bridge", though, for reasons having to do with how 802.11
operates.

If you need to do this (have multiple devices out at the Ubiquity
location) you may be better off running a "routed" configuration.  In
this arrangement, the Ubiquity would act as a client device on your
home WiFi network (it would be given its own IP address via DHCP or
static assignment).  It would actually serve an entirely separate IP
network on its wired-Ethernet side - it would act as a DHCP server for
clients on this network.  It would route packets from these clients to
the home LAN (wired and wireless) and the Internet by forwarding them
to your home's main router/AP.  The router/AP would need to have one
new bit of configuration information added: you would have to add a
"route" entry, telling it that packets for the second IP network (on
the far side of the Ubituity) would need to be transmitted to the
Ubiquity for forwarding.  Some systems can handling this routing setup
for you in a mostly-automatic way; you would probably need to enable a
feature like RIP so that the various routers can exchange routing
information on their own and figure out the right packet routes.



Re: Can a router be a router and an access point at the same time?
On Wed, 07 Aug 2013 17:49:38 +0000, Jesse wrote:

Quoted text here. Click to load it
=======================================================================
Your router (if it is at all typical) comes set up as an access point.
Can you use a laptop to connect to it within ~100 ft? I bet you can.
If not, fix that first. BTW, why don't you mention what kind of router/AP
it is? Don't make people guess.  

From http://dl.ubnt.com/datasheets/bulletm/bm_ds_web.pdf
"...create a powerful and robust outdoor Access Point, Client, or Bridge."
It has an ethernet connector and uses PowerOverEthernet. The PDF
describes the software you need to use to point the thing. Deal with
that next. Get it pointed and picking up the signal that you checked
in the previous paragraph.

What do you want to connect to the Bullet M2? A single system? Then it's
a matter of configuring the Bullet. It might even configure itself using
the DHCP daemon in your (typical) router/AP. Are you worrying before you
even tried it?

If you want to connect the Bullet to another network, then you get into
the details.


Re: Can a router be a router and an access point at the same time?
On Wed, 07 Aug 2013 15:45:43 -0500, Zaphod Beeblebrox wrote:

Quoted text here. Click to load it

I didn't think it mattered because it's your typical home
broadband router. It's the WRT54G, version 5 router.


Re: Can a router be a router and an access point at the same time?
On Wed, 07 Aug 2013 17:49:38 +0000, Jesse wrote:

Quoted text here. Click to load it
=======================================================================
Your router (if it is at all typical) comes set up as an access point.
Can you use a laptop to connect to it within ~100 ft? I bet you can.
If not, fix that first. BTW, why don't you mention what kind of router/AP
it is? Don't make people guess.  

From http://dl.ubnt.com/datasheets/bulletm/bm_ds_web.pdf
"...create a powerful and robust outdoor Access Point, Client, or Bridge."
It has an ethernet connector and uses PowerOverEthernet. The PDF
describes the software you need to use to point the thing. Deal with
that next. Get it pointed and picking up the signal that you checked
in the previous paragraph.

What do you want to connect to the Bullet M2? A single system? Then it's
a matter of configuring the Bullet. It might even configure itself using
the DHCP daemon in your (typical) router/AP. Are you worrying before you
even tried it?

If you want to connect the Bullet to another network, then you get into
the details.


Re: Can a router be a router and an access point at the same time?
On Wed, 07 Aug 2013 15:54:45 -0500, Grover Cleveland wrote:

Quoted text here. Click to load it

Yes. I have access to 120v power about a half mile from the house  
and I just want to set up the Bullet M2 pointing at the Linksys  
WRT54G inside the house.

Connected to the Bullet M2 will be a 24v POE, and on the other  
end of the Ubiquiti POE will be a laptop.

The antenna is a 14 dBi planar antenna connected to the Bullet M2.

The view will be unhindered and is a direct line of sight at chair  
level, so I don't even have to mount the antenna (although I probably  
will so as to keep it aimed when not in use).


Re: Can a router be a router and an access point at the same time?
On Wed, 7 Aug 2013 17:49:38 +0000 (UTC), Jesse wrote:
Quoted text here. Click to load it

It's difficult to determine what your Amateur Radio Antenna qustion is.


Re: Can a router be a router and an access point at the same time?


< snip >

Quoted text here. Click to load it

Maybe you need to bone up on mesh networks.  Developments are
coming fast and furious and some of the router channels are in ham
bands, so he could, in fact be on-topic. I wish I knew enough to
answer Jesse.  



Re: Can a router be a router and an access point at the same time?
On Wed, 07 Aug 2013 17:49:38 +0000, Jesse wrote:

Quoted text here. Click to load it
=======================================================================
Your router (if it is at all typical) comes set up as an access point.
Can you use a laptop to connect to it within ~100 ft? I bet you can.
If not, fix that first. BTW, why don't you mention what kind of router/AP
it is? Don't make people guess.  

From http://dl.ubnt.com/datasheets/bulletm/bm_ds_web.pdf
"...create a powerful and robust outdoor Access Point, Client, or Bridge."
It has an ethernet connector and uses PowerOverEthernet. The PDF
describes the software you need to use to point the thing. Deal with
that next. Get it pointed and picking up the signal that you checked
in the previous paragraph.

What do you want to connect to the Bullet M2? A single system? Then it's
a matter of configuring the Bullet. It might even configure itself using
the DHCP daemon in your (typical) router/AP. Are you worrying before you
even tried it?

If you want to connect the Bullet to another network, then you get into
the details.

Re: Can a router be a router and an access point at the same time?
On Wed, 07 Aug 2013 18:16:59 -0500, Chester A. Arthur wrote:

Quoted text here. Click to load it

Hmmmmmmmmmmmm. I don't think so. I tried and I can't even *see* the  
home SSID access point from the laptop.  

Admittedly, the laptop has a lousy wireless NIC and antenna (probably  
on the order of 50mW and 1/2 dBi) and, I probably could spend a hundred
to get a USB antenna and radio but it's a Linux laptop and I've already
tried and failed (in the past) with finding suitable USB drivers for
USB wireless devices.

Besides, the Bullet M2 output power is something on the order of  
28 dBm, so it should *easily* go the half mile needed.


Re: Can a router be a router and an access point at the same time?
On 8/8/2013 7:39 PM, Jesse wrote:
Quoted text here. Click to load it

The alfa tube-u works fine under linux. The drivers are in the kernel.  
But if you set up the M2 as a client, it should work. Don't forget to  
check the M2 manual for the antenna polarity.

Power doesn't matter much if yo don't have it on both ends.

Re: Can a router be a router and an access point at the same time?
On Thu, 08 Aug 2013 20:12:44 -0700, miso wrote:

Quoted text here. Click to load it

That's my biggest concern.

I'm hoping the sensitivity of the Bullet makes up for the lack  
of transmit power of the WRT54G.


Re: Can a router be a router and an access point at the same time?
On 8/7/2013 10:49 AM, Jesse wrote:
Quoted text here. Click to load it

 From the M2 literature, the device can be an access point, bridge, or  
client. If you are connecting one device to the M2, say a notebook, you  
want to configure the M2 as a client. If you are going to connect the M2  
to a switch, I think you want to make it a bridge, but I am not 100% sure.

Bridging is a little tricky if you DHCP (which I assume you will). But I  
don't want to clutter up this point if you are just going to be a client.

Be sure you understand the polarization of your WAP and the M2. Most  
WAPs will be vertically polarized. Just read the M2 manual to insure uou  
set it up to be vertically polarized.

I've done wifi over a few miles to just a wifi router on a wall. But  
generally backhaul (point to point) wifi is done with two directional  
antennas and often using horizontal polarization. There is some loss if  
the transmitter and receiver are not polarized the same way. Since most  
wifi is vertically polarized, you do the back haul horizontally and take  
advantage of such loss to reduce interference.


Re: Can a router be a router and an access point at the same time?
On Wed, 07 Aug 2013 17:05:47 -0700, miso wrote:

Quoted text here. Click to load it

I have never understood this stuff!  
So, thanks for the advice.

I'm planning on connecting the Bullet M2 only to a laptop via the  
Linux laptop wired (eth0) Ethernet NIC.

The laptop just needs to know:
1. IP address (e.g., 192.168.1.200/255/255/255/0)
2. Gateway (e.g., the IP address of the Bullet M2, whatever that is)

The Bullet M2 needs to know a lot more, it seems:
a. SSID & password of the Linksys WRT54G a half mile away
b. Whether it is a router or a bridge or access point

I don't remember seeing "client" as an option. I have to look again!


Re: Can a router be a router and an access point at the same time?
On 8/7/2013 12:49 PM, Jesse wrote:
Quoted text here. Click to load it

Can you give more detail.  What do you have including details, and what  
are do you want to do.

Give as many details and wishes as possible.  It may seem trivial to you  
but it all is important to what may meet your need.

i.e. do you need to have access to just the internet from wireless  
devices, or do you need to connect to things on your local Microsoft  
home or work network?

The answer to that one will change what you equipment you need.  If you  
want to do it securely.

tom
K0TAR


Re: Can a router be a router and an access point at the same time?
On Thu, 08 Aug 2013 22:23:17 -0500, tom wrote:

Quoted text here. Click to load it

I'm not worried about security (it's a guest network anyway, with an  
extremely weak password, on purpose).

The devices are three:
1. WRT54G is the home broadband router
2. Bullet M2 with a 14 dBi planar antenna is the radio 1/2 mile away
3. Standard Linux laptop is the PC connected to the Bullet

The only goal is to have the laptop on the Internet from 1/2 mile away
from the Linksys WRT54G router using the Bullet M2 as it's radio.


Re: Can a router be a router and an access point at the same time?
wrote:

Quoted text here. Click to load it

Thank you for finally disclosing what you're trying to accomplish and
what you have to work with.

The WRT54G v5 and v6 are junk.  I can supply reasons why they're junk
later but the big problem is that they just love to hang.  I've slowly
been removing them from customers and hotspots and have built up quite
a collection.  Think about a replacement such as another Ubiquiti
Bullet M2.

Let's do some path loss calcs.  The assumption is that you have line
of sight and that there are no obstructions in the path or in the
Fresnel zone.  Follow my example at:
<http://wireless.navas.us/index.php?title=Wi-Fi#Link_Calculations

M2 end ....
  TX power M2    = +17dBm (non HP version)
  TX coax loss   = 0 dB with antenna mounted to M2 radio
  TX ant gain    = +14 dBi panel
  Distance       = 0.5 miles
  RX ant gain    = +2 dbi rubber ducky
  RX coax loss   = 0 dB with rubber ducky mounted on router
  RX sens        = -84 dBm (at 12 Mbits/sec)
WRT54G v5 end ....
  Fade margin    = unknown

Argh.  The YDI link calculator has moved again.  Now it's at:
<http://www.proxim.com/products/knowledge-center/calculations/calculations-system-operating-margin-som
Plugging in the numbers, I get a fade margin of 18.8 dBm.  That's
sufficient and should work just fine if there are no obstructions in
the path.  

If you are shooting through a wall, window, trees, or don't have line
of sight, you're going to have problems.  The numbers never get
better, only worse.  Also, interference might be a problem if it is
located along the line of sight of the +14dBi antenna, which will
increase both the signal from the WRT54G and any interference that it
sees.  You might want to do a "site survey" along your intended path
with the +14dBi antenna and UBNT Bullet M2 to check for potential
problems.
    
--  
Jeff Liebermann     jeffl@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann     AE6KS    831-336-2558

Re: Can a router be a router and an access point at the same time?
On 8/7/2013 1:49 PM, Jesse wrote:
Quoted text here. Click to load it

One word of caution.  In many countries it is illegal to connect an  
external antenna as you described.  You need to check your country's  
laws before doing so.  I'd hate to see you get in trouble unnecessarily.

--  
==================
Remove the "x" from my email address
Jerry Stuckle
JDS Computer Training Corp.
jstucklex@attglobal.net
==================

Re: Can a router be a router and an access point at the same time?
wrote:

Quoted text here. Click to load it

Well, it all depends on how you configure the BOX....... Most Home  
Wifi Boxes have an AccessPoint, (WiFi Radio) a Ethernet Switch, (LAN  
Ports) and Router, (Wan Port) all built-in to the One Box. The Ethernet
Switch connects ALL the LAN Ports, WiFi Radio Port, and Router LAN Port  
together.  
SO, if you do NOT need the Router Portion, just connect you local  
Network to one of the LAN Ports and away you go, since the WiFi Radio is  
just another Port, on the Ethernet Switch.

If you need the Router Portion, for local Subnet Routing, then you  
connect your LAN to the WAN Port and setup the WiFi and Ethernet Switch  
as a different subnet than your Main LAN. (This what I do for Customer  
Access via different Access Points around my LAN so I can know who is  
using what Access Point, and when. Each Access Point does it's Own DCHP  
for the WiFi, and local SubNet it is setup for)

If you have a simple LAN Network and this BOX is your Main Router, then  
the WAN Port goes to your Internet Access Device or Port, and the Router  
LAN Port on the Ethernet Switch outputs the routed Packets to the  
appropriate Switch Ports. (LAN Ports and WiFi Radio Port)

Clear as Mud.... right?  Oh Well.....

Site Timeline