""Zsombor Papp"" wrote in message news:[EMAIL PROTECTED] > At 08:34 PM 6/17/2003 +0000, Priscilla Oppenheimer wrote: > >Access points can be configured to do bridging and I wouldn't be surprised > >to discover that they don't do STP, especially low-end ones from the local > >KMart. A lot of low-end switches don't do STP either. > > Yet they filter out BPDUs? If they don't, then assuming proper > configuration on the "high end" switches, can there be really loop? > > > So, the access point > >would have to be inserted into the network just right so that it caused a > >loop, but that's certainly possible. In that case all the looping broadcast > >traffic, not to mention looping unknown unicast traffic, could bring a > >network to its knees. > > > >I'm surprised so many people doubted his decription of the problem!? > > A 6509 can switch multiple gigabits of traffic without any problems. You > would need quite a few wireless loops to kill such a box. I might be > missing something but I still doubt that "a user with an integrated > wireless and LAN NIC" can kill bring down a network of 6509 and 3550 > switches.
Not knowing firsthand, I've checked the Cisco documentation. For the 1200 series of AP's, at least, I can find no reference to spanning tree. Not saying it isn't there. Just saying I see no reference. every AP with which I am familiar has but a single ethernet port. It is essentially a hub, although some of the vendors have some pretty sophisticated capability build in as part of their firmware and OS. I've been working with Proxim on a deal, with 802.1x port based authentication. The particular Proxim device creates virtual ports for end stations, and communicates with radius to ensure that the user can authenticate against the 802.1x database, even as the user moves from AP to AP. It is not inconceivable that putting in a series of wireless AP's could create a loop somewhere. Particularly if there are rogue devices out there and someone is wandering among them. Just thinkking out loud, but the switch would see a user MAC comming into different ports as the user moved around. Thinking out loud again, with an authorized and reasonably thought out wireless installation, all your AP's would be in the same subnet/vlan and users wandering from AP to AP would cause no problems becasue to the back room switch the user mac would be on the same vlan as it moves. as far as the switch is concerned, nothing untoward has happened. Unless something is terribly wrong - i.e. major bug in the AP software - users cannot be connected to more than one access-point simultaneously ( if they could, that might cause loop problems ) generally, the wireless nic firmware negotiates connection to the AP with the strongest signal in a mobile situation. Once in a while I see a comment that leads to believe that there may be some misunderstanding about the term "bridge" when used in conjunction with wireless. A wireless bridge is a device for point to point wireless communication with another wireless bridge. It is more like a serial link than what most folks think of when they hear the term "bridge". one of those newfangled terms that is in the purist sense misused, but neverless is used differently than in the world of switches. So, one way for wireless, with it's single ethernet port, to create a loop would be for it to bridge to anther AP, which in turn is plugged into the same switch. Loops would form and the ensuing broadcast storm could wreak havoc. > > Thanks, > > Zsombor Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=70832&t=70797 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
