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Date: Sat, 23 Aug 2003 01:08:44 EST5EDT4,M4.1,M10.5
Sender: os2-wireless_users-owner <os2-wireless_users-owner@2rosenthals.com>
Reply-To: os2-wireless_users@2rosenthals.com
From:  Lewis G Rosenthal <os2-wireless_users@2rosenthals.com>
To:  os2-wireless_users@2rosenthals.com
Subject: [OS2Wireless] Wireless nomenclature

Charles -

Charles McCallister wrote:

>Lewis, 
>
>Well, it seems that I've learned the concept of bridge though let me get
>this  straight. Working backward, the AP is the transceiver, the router is
>the IP  connector (for lack of better terminology) and the bridge is the
>DSL modem  hardware?
>
So far, so good. The difference between a bridge and a router is that a 
router connects two separate ethernet networks of the same topology 
(that's redundant; it connects two _ethernet_ networks). A bridge, OTOH, 
connects two different topologies, thereby creating a "bridge" between 
them. For DSL, this typically (in the case of SDSL and ADSL) means 
connecting an ethernet network to an analog telephone connection (I 
know, I know... DSL means *digital* subscriber line...).

> And when DSL is down, the bridge is capable of using
>an analog modem  for a dial-up connection? About right?
>
No. You'd need either a router configured to detect the dead link (dead 
link detection, as it is commonly called; fancy that?) and then re-route 
the connection to a second routed (WAN) port, which in this case, would 
not be ethernet, but rather serial, to which a modem would be connected 
(either externally, as in the Nexland ISB100, or internally). The other 
alternative would be something akin to Cisco's HSRP (hot start routing 
protocol) where two or more separate routers are configured to act as 
one logical unit. One router is designated as the primary, and the 
others fall behind, in suit. When a dead link is detected by the primary 
(or the primary fails), the secondary fires up an alternate route. As 
the units are configured to share a single logical IP address, the 
clients don't know the difference, as their default gateway address 
hasn't changed.

> Also, what's a
>switch? 
>
An intelligent hub. A hub merely divides bandwidth equally among all 
connected devices. This is the way Wi-Fi access points work, too. It is 
analogous to a lawn hose splitter, where equal amounts of water flow 
through each outlet of the splitter. A switch, OTOH, manages bandwidth 
much more efficiently, by taking advantage of the packetization of data 
and rapidly switching on and off the different connections. This gives 
the appearance to the devices that each one has a dedicated connection 
with (practically) a full pump. Pretty slick.

>BTW, I've now been able to connect my IBM UltraPort Camera II (USB) to the
>TP  and look forward to video conferencing. Is anyone doing this over their
> wireless DSL connection yet? Any success? Pros and Cons? Gotchas?
>Suggestions  for hardware? 
>
I've thought about getting an UltraPort camera, but I didn't think there 
were any OS/2 drivers available (there's a familiar song, huh?).

-- 
Lewis
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