BSS Versus IBSS
BSS/Master/AP/Infrastructure/IBSS/Ad-Hoc/Peer-to-Peer: these all refer to 802.11b operating modes, but what does it all mean?
802.11b
(see [Hack #3]
) defines two possible (and mutually
exclusive) radio modes that stations can use to intercommunicate.
Those modes are BSS and
IBSS.
BSS stands for Basic Service
Set. In this operating mode, one station (the
BSS master
, usually a piece of hardware called an
access point
) acts as a gateway between the
wireless and a wired (likely Ethernet) backbone. Before gaining
access to the wired network,
wireless clients (also called BSS
clients) must first establish communications with an
access point within range. Once the AP has authenticated the wireless
client, it allows packets to flow between the client and the attached
wired network, either routing traffic at Layer 3, or acting as a true
Layer 2 bridge. A related term, Extended Service Set
(ESS), refers to a physical subnet that
contains more than one access point (AP). In this sort of
arrangement, the APs can communicate with each other to allow
authenticated clients to “roam”
between them, handing off IP information as the clients move about.
Note that (as of this writing) there are no APs that allow
roaming across networks
separated by a router.
IBSS (Independent
Basic Service Set) is frequently referred to as
Ad-Hoc or Peer-to-Peer mode. In this mode, no hardware AP is required. Any network node that is within range of any other can communicate if both nodes ...