Advices on wireless switches.

Hi

My company will install some wi-fi AP and I am search some infos
on wi-fi switches
I've read some docs about them but have no practice of it ...

I saw Extreme-networks products which seems very interresting

Any infos/feedback welcome.

Thanks

"frank" <(E-Mail Removed)> wrote in message
news:41c162fd$0$3517$(E-Mail Removed). ..
> Hi
>
> My company will install some wi-fi AP and I am search some infos
> on wi-fi switches
> I've read some docs about them but have no practice of it ...
>
> I saw Extreme-networks products which seems very interresting
>
> Any infos/feedback welcome.
>
> Thanks

There are quite a few new wireless switches on the market.
Most provide for centralized management of all the AP
like upgrading firmware, load balancing etc. The move is in the
direction
of Thin-APs (less smarts, less expensive) with the switch being the
brains.
Some of them are using proprietory technology which means
you will probably need to use their APs also to take full advanage
of the switches capabilities. The Extreme switch (uses proprietory
technology)
There are others: It just depends on your budget.

http://www.airespace.com/
http://www.symbol.com/
http://www.cisco.com
http://www.trapezenetworks.com

How many Aps are you going to install?

You should also check out chantrynetworks.com - they are using routin
rather than switching and in the long run that should be mor
versatile

--
wiology200
brought to you by http://www.wifi-forum.com

Hi, can you explain why you think routing at L3 is better
than L2?

wiology2004 wrote:
> You should also check out chantrynetworks.com - they are using routing
> rather than switching and in the long run that should be more
> versatile.
>
>

On Thu, 16 Dec 2004 16:58:58 -0800, Kevin Hill <(E-Mail Removed)> wrote:

>Hi, can you explain why you think routing at L3 is better
>than L2?

Layer 2 is bridging, not routeing.
Layer 3 is routeing.

(Is it routeing or routing?)

A bridge has no concept of CIDR or netmask. Therefore, you can't just
say "take all the traffic on this here network and shove it through a
gateway over to yonder network". That's easy with a router. With
bridging, each MAC address is unique with no guaranteed commonality
with other machines on the same network. Therefore, to do routeing on
Layer 2, you would need a route for every single last lousy MAC
address on the network. That's not very practical or useful.

Also, with bridging, the manufactory assigns the MAC address (although
it can be changed). With routeing, the network admin or the DHCP
server assigns the IP address, giving much more control over
organization, topology, and routeing on Layer 3.

Also, Layer 2 has no concept of services, such as http, ftp, telnet,
etc. Layer 3 routeing allows you to control traffic by these
services. Layer 2 only knows about ethernet and cannot distinguish
the different types of traffic.

ALL (and I do mean all) wireless contraptions are Layer 2 bridges. A
wireless bridge know nothing about Layer 3 (TCP/IP) features and
functions. All it knows is ethernet and MAC addressing. If the
destination MAC address is across the bridge, the traffic will pass
over the bridge. If not, it won't pass. More simply, all 802.11
wireless does is encapsulate 802.3 ethernet packets, send them over a
radio link, and reconstruct the original 802.3 ethernet packets at the
destination end. Crudely, it's an extension cord for ethernet.

A wireless router is nothing more than a wireless bridge with an
ethernet router glued onto one of the wireless (switch) ports. The
function of the router is quite independent of the wireles bridge
section.


--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831.336.2558 voice http://www.LearnByDestroying.com
# (E-Mail Removed)
# (E-Mail Removed) AE6KS

Jeff Liebermann wrote:
> On Thu, 16 Dec 2004 16:58:58 -0800, Kevin Hill <(E-Mail Removed)> wrote:
>
>
>>Hi, can you explain why you think routing at L3 is better
>>than L2?
>
> Layer 2 is bridging, not routeing.
> Layer 3 is routeing.

Yes, i didn't say L2 was routing.

> (Is it routeing or routing?)

The latter.

> ALL (and I do mean all) wireless contraptions are Layer 2 bridges. A
> wireless bridge know nothing about Layer 3 (TCP/IP) features and
> functions. All it knows is ethernet and MAC addressing. If the
> destination MAC address is across the bridge, the traffic will pass
> over the bridge. If not, it won't pass. More simply, all 802.11
> wireless does is encapsulate 802.3 ethernet packets, send them over a
> radio link, and reconstruct the original 802.3 ethernet packets at the
> destination end. Crudely, it's an extension cord for ethernet.

I don't think it is all. Chantry supposedly works at L3. There's no real
reason to have L2 work at all. It's just easier because the
chips do the mac learning for you. I think L3 is really the way to go.
Let the AP proxy arp for all the ip addresses used by the station.
Then there's no possibility of arp poisoning attacks.

On Thu, 16 Dec 2004 20:24:37 -0800, Kevin Hill <(E-Mail Removed)> wrote:

>> (Is it routeing or routing?)

>The latter.

Ok. Google shows 53,000 hits for routeing and 15 million hits for
routing. Routing wins.

>> ALL (and I do mean all) wireless contraptions are Layer 2 bridges. A
>> wireless bridge know nothing about Layer 3 (TCP/IP) features and
>> functions. All it knows is ethernet and MAC addressing. If the
>> destination MAC address is across the bridge, the traffic will pass
>> over the bridge. If not, it won't pass. More simply, all 802.11
>> wireless does is encapsulate 802.3 ethernet packets, send them over a
>> radio link, and reconstruct the original 802.3 ethernet packets at the
>> destination end. Crudely, it's an extension cord for ethernet.

>I don't think it is all. Chantry supposedly works at L3. There's no real
>reason to have L2 work at all. It's just easier because the
>chips do the mac learning for you. I think L3 is really the way to go.
>Let the AP proxy arp for all the ip addresses used by the station.
>Then there's no possibility of arp poisoning attacks.

First let me apologize. I could not divine your level of expertise
from your two terse messages. Therefore, I assumed[1] that you were
asking a beginners question and did not understand the difference
between bridging and routeing, er.. routing. Obviously I misread the
question. Sorry.

I've never considered the possibility of locking the MAC layer and
doing eveything at the IP layer. I agree, it seems like a good idea.
The FAQ covers the benifits:
http://www.chantrynetworks.com/site/...upport/faq.asp
It certainly would fix the roaming and portable IP problem as well as
block various layer 2 attacks.

[1] Assumption, the mother of all screwups.


--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 AE6KS 831-336-2558

thanks for all your answers guys.

Jeff Liebermann wrote:
> On Thu, 16 Dec 2004 20:24:37 -0800, Kevin Hill <(E-Mail Removed)> wrote:
>
> Ok. Google shows 53,000 hits for routeing and 15 million hits for
> routing. Routing wins.

Dictionary.com is authorative for me. On the net I find too many people
are as bad a speller as I am :-)


> First let me apologize. I could not divine your level of expertise
> from your two terse messages.

No need to apologize. I look forward to your posts.
I also hope you do a book someday of your exploits.
They are always interesting.

On Fri, 17 Dec 2004 05:21:25 -0800, Kevin Hill <(E-Mail Removed)> wrote:

>Jeff Liebermann wrote:
>> On Thu, 16 Dec 2004 20:24:37 -0800, Kevin Hill <(E-Mail Removed)> wrote:
>>
>> Ok. Google shows 53,000 hits for routeing and 15 million hits for
>> routing. Routing wins.

>Dictionary.com is authorative for me. On the net I find too many people
>are as bad a speller as I am :-)

I usually use dict.org. It's not just the spelling. I'm also having
problems with the pronounciation. On the left coast, it's pronounced
"rou-ter". In the UK, it's "roo-ter". In the south, it's "rou-tah".
I've also heard "rah-ter" but I didn't ask where that came from.

>I also hope you do a book someday of your exploits.
>They are always interesting.

It will probably not happen. I have a friend that scribbles computah
books and others that do self-publishing. Both require substantial
self-promotion, travel, book signing, investments, and time. After
watching how it's done, I don't think I can do all that. I'm not very
presentable, detest travelling, and am quite lazy. I know of one
author that hired a stand-in to do all the hand shaking, book signing,
and pose for the cover liner. However, that drastically reduced the
book revenue. I do have some ideas for a book, but they have nothing
to do with wireless, computahs, or the internet. Thanks for the
interest.


--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 AE6KS 831-336-2558