Heh, you should have been at Networkers 2003 in LA. Cisco's wireless network was... Unstable to say the least. I'd estimate that the network was available only 50% of the time. First someone hacked into the DHCP server and brought that down. They someone set their IP address the same as the default route. Then people setup peer-to-peer networks with the same ESSID as the Cisco AP's. It was almost comical!
Fred Reimer - CCNA Eclipsys Corporation, 200 Ashford Center North, Atlanta, GA 30338 Phone: 404-847-5177 Cell: 770-490-3071 Pager: 888-260-2050 NOTICE; This email contains confidential or proprietary information which may be legally privileged. It is intended only for the named recipient(s). If an addressing or transmission error has misdirected the email, please notify the author by replying to this message. If you are not the named recipient, you are not authorized to use, disclose, distribute, copy, print or rely on this email, and should immediately delete it from your computer. -----Original Message----- From: DeVoe, Charles (PKI) [mailto:[EMAIL PROTECTED] Sent: Thursday, July 17, 2003 8:39 AM To: [EMAIL PROTECTED] Subject: RE: STP problem [7:70797] We had a similar situation. Only in this case, the user was taking down internet access. Seems whoever configured the machine put the default gateway in as the users address. At the time we were running two protocols, decnet and tcp/ip. Decnet was the first one to be used. The only time there was a problem was when the user would try to access the internet. After a week of troubleshooting, we started looking at all of the PCs that had been installed recently. It was pure luck that we found it. -----Original Message----- From: Priscilla Oppenheimer [mailto:[EMAIL PROTECTED] Sent: Tuesday, June 17, 2003 4:35 PM To: [EMAIL PROTECTED] Subject: Re: STP problem [7:70797] 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. 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!? Anyway, finding it will be hard, though there's good advice from Tom and others. I think I would revert to an old-fasioned communications channel. Announce over the loud speaker that if you just connected a wireless access point, disconnect it now and report to the office! :-) Priscilla Tom Martin wrote: > > Chris, > > STP should be enough to avoid these types of problems. In order > to cause > a bridging loop the station would have to have both interfaces > in the > same VLAN and forward all L2 traffic except for BPDUs. Even if > this were > the case the wireless network (10-Mbps?) shouldn't be enough to > bring > the LAN to its knees (100-Mbps?). If you have STP enabled on > all of your > switches, I'm doubt that a single station is bringing the > network down. > > Once you find the offending switch that you need to reboot, you > can > issue console commands to determine the root bridge and any > blocked > ports. Make sure that things are normal. You do have your root > bridge > set manually, don't you? :) > > To find out which port is causing the loop, take a look at the > interface > counters. You should see an unreal amount of traffic on the > offending > port (and the uplink to the core switch). > > When STP has been enabled I have only come across layer-2 loops > twice. > Once when a few HP switches had gone bad, and another time when > a > customer had configured channeling on one side but not the > other (3500 > series, no channel negotiation). > > In both cases I found that the problem was made worse with > increasing > traffic levels, and the problem also revolved around the same > set of > switches. The channeling problem was a bit more difficult to > narrow down > though, since it disabled MLS on the core switch and every > segment > appeared to have problems!!! > > I hope that helps, > > - Tom > > > Christopher Dumais wrote: > > Hi all, > > We are having an STP problem where we think a user with an > integrated > > wireless and LAN NIC is creating a bridge loop and bringing > down the entire > > network. The problem occurs then goes away after 20 or so > minutes unless we > > can narrow down which closet it is coming from and reboot the > switch. All of > > our management tools die during the outage. Does anyone have > any ideas on > > how we might prevent this from happening or track down the > offender? We have > > 6509's in our Core and a mix of 3548's and 3550-SMI. Any > thoughts are > > appreciated. Thanks! > > > > Chris Dumais, CCNP, CNA > > Sr. Network Administrator > > NSS Customer and Desktop Services Team > > Maine Medical Center > > (207)871-6940 > > [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=72482&t=70797 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
