AD HOC vs Infrastructure Mode
Mike Cox
Is there a performance advantage when using Infrastructure mode as opposed
to Ad Hoc mode?
I have set up a point to multipoint network using a Cisco PCI352 card in a
Windows 2000 server. ISA server is installed for Firewall, Caching and
connection sharing (NAT). I am thinking I will switch over to Linux once I
am more comfortable with working with it.
This type of setup requires that I run in AD HOC mode and my clients connect
in AD HOC mode. If I went with an Access Point and ran in Infrastructure
mode would I see a performance advantage? Right now the system seems to
work very fast but what about when I get more users on?
Concerns...
Will an AP support more concurrent users?
Will and AP provide a more reliable connection?
Thanks
Robert Nicholas
"Mike Cox" <mc...@nwon.com> wrote in message
news:hyoB7.322794$j65.86...@news4.rdc1.on.home.com...
Yes. Ad hoc mode requires a bit more overhead to operate, whereas an AP can
produce better results by centralizing control at the AP. This centralized
control is not realy necessary unless you want the max badwidth and have
more that, say, 3 clients.
> Will and AP provide a more reliable connection?
Yes. In ad hoc mode, the clients are all trasient clients -- they can move
into and out of you network PYSICALLY and in terms of connectivity.
Further, for your ad hoc network to function "normally," all clients must
see each other. Since the responsibilities for the beacon frame handling is
passed around, some clients may spontaneously drop from the network and
reappear.
This may not be so much of a problem either if you're working in a home.
Unless you have a lot of RF holes due to multipath or are working in a
large, multistoried area (with metal trusses in the floors, for example) you
may have few problems at all.
Regards,
Robert
Robert B.
be better than running your WLAN from one of your CPU's, but depending on
your needs, I'm not sure that "built-in" is better. You will still have
wires on a wireless system. One of which is connected to your backbone
connection.
Suppose that you have a wired LAN with a need to "stretch" your connection
range as far as possible to reach a far corner of your desired coverage
area. An stand-alone access point would be a better alternative, providing
the flexibility you wanted when you decided to go wireless in the first
place. Place the access point where best suited on the network rather than
back at the router.
Of course, the needs and requirements of the end-user will be the final
deciding factor. I just think that the flexibility of a stand alone is a
better value. You may only need a very tight coverage area now, but will
your needs change later? Consider if your router is well centered in your
coverage area. Most of the time this is not the case.
If you are going to abandon a wired LAN altogether, then a wireless router
might be the solution, but I personally am not ready to move backward from
100Mbps to 5.5Mbps for my local needs. In my opinion, the best and highest
use for a wireless router is for LAN to LAN bridging, and I would still have
to think long and hard about losing the modular configuration capabilities
of stand-alone bridging.
I must strongly agree with Robert when he says that your bottle-neck is at
your WAN connection. Even at 5Mbps, your moving many more times the data
locally than you'll ever see with your 128Mbps connection. Going wireless
in this manner will do nothing for your Internet connectivity. It will
continue to limp along as it always has.
In short, don't expect an internal application of wireless to improve your
speeds either on your LAN, or on the Internet. It's not ready for that on
the LAN side (although high-speed wireless ISP service is another story best
reserved for another writing session). Typical reasons to go wireless are
mobility, rapid deployment and reconfiguration of LANS and the elimination
of redundant/recurring ISP charges and services. These products can pay for
themselves over and over again by eliminating the hassles and isolation of a
wired LAN. It should not replace your wired LAN for speed enhancements
(yet).
--
Managing Director
Certified Cisco Aironet Wireless Specialists
Webcats Wireless Networks
http://WebcatsWireless.com
> I suppose you could use ICS, but in my opinion, using a router with a
> built-in access point is better. If you ever have to restart the computer
> running ICS, all other computers in the house will lose connectivity.
> Routers are always on.
>
> What about bottlenecks? If you're using a 128k connection, it will be that
> connection that is your bottleneck. The 1.1 Mpbs you mentioned is the
> minimum. There are devices available that deliver 11 Mbps (and with 802.11a
> devices, there will soon be speeds up to 108Mbps with data rate doubling).
>
> With a 128k inet connection and a 1.1Mbpd rated data throughput, you'd
> probably want no more than, say, 15 clients on a low-traffic WLAN and no
> more that 5 or 6 on a high-traffic WLAN. Beyond that, collisions may become
> a SERIOUS problem.
>
> Regards,
>
> Robert
>
>
> "jay" <jay.b...@canada.com> wrote in message
> news:3bb0ec0a$1...@news.ucsc.edu...
>> I'm trying to find out why, on a small home network, pretty much
> exclusively
>> for Internet sharing, an AP is more desirable than a wireless network
> card,
>> an external antenna and a little bit of routing.
>>
>> Also, what sort of limit of clients would there be for an Internet sharing
>> network? If the Internet connection were only, say, 128 Kbps, wireless
>> 802.11b is 1.1 Mbps minimum, which is 8+ times faster than the shared
>> connection. Why would there be any significant limit? Yes, there would
> be
>> a lot of collisions, but that should all sort out without any significant
>> delay to clients. Or am I missing something?
>>
>> Input is keenly desired.
>>
>> Thanks
>> jay
in article tva44o6...@corp.supernews.com, Robert Nicholas at
rob...@p3wireless.com wrote on 11/16/01 8:09 AM:
Robert Nicholas
"Robert B." <im4...@home.com> wrote in message
news:B82542F4.3B8%im4...@home.com...
> I agree with Robert that using a router with a built-in access point would
> be better than running your WLAN from one of your CPU's, but depending on
> your needs, I'm not sure that "built-in" is better. You will still have
> wires on a wireless system. One of which is connected to your backbone
> connection.
You are right, of course, but many times, this "wired backbone" consists of
the 6' Cat5 cable that runs from the cable modem to the router/PC.
> Suppose that you have a wired LAN with a need to "stretch" your connection
> range as far as possible to reach a far corner of your desired coverage
> area. An stand-alone access point would be a better alternative,
providing
> the flexibility you wanted when you decided to go wireless in the first
> place. Place the access point where best suited on the network rather
than
> back at the router.
>
> Of course, the needs and requirements of the end-user will be the final
> deciding factor. I just think that the flexibility of a stand alone is a
> better value. You may only need a very tight coverage area now, but will
> your needs change later? Consider if your router is well centered in your
> coverage area. Most of the time this is not the case.
For most home users, the cost (camparatively low as it may be) may still be
prohibitive in terms of setting up an all-at-one WLAN. For those who cannot
afford this approach, I would look very carefully at an incremental approach
which would get you on a WLAN while still leaving options open.
If this is not the case, and you can afford to make the transition in one
step, then Robert B. definitely has some good points.
Absolutely right! In a home environment (as I assume dangerously I
suppose), if you're not looking for mobility then a WLAN may not be the best
solution. WLANs are quite a lot slower than wired LANs are, with very few
exceptions.