Separate VLANs (not overlapping) The four switches are connected for redundancy purposes. Business unit A has resources upstream that business unit B must be able to access (but still needs to remain separate administratively)
As the shabby diagram depicts, each business unit switch is trunked together to share vlan info but the links between business unit switches are access links in separate vlans. The problem I believe im facing here is the fact that portfast was enabled (bad mistake) and causing the ports to forward straight away and not listen to bpdu's in order to block one of the links. Cheers, Aaron. -----Original Message----- From: Tom Sands [mailto:[EMAIL PROTECTED] Sent: Friday, February 01, 2008 9:36 PM To: Aaron R Cc: [email protected] Subject: Re: [c-nsp] Spanning-Tree question Though you using 2 different VTP domains/VLAN databases, are the VLANs per business unit at least unique so the VLAN databases don't have overlapping VLANs? What's the purpose of interconnecting the 4 switches? What are the connections between the 4 switches? access port (same vlan on each side or every switch)? trunk? L3? ------------------------------------------------------ Tom Sands Chief Network Engineer Rackspace (210)312-4391 ------------------------------------------------------ Aaron R wrote: > Hi Guys, > > > > Ive got a problem that I am hoping someone can have a look at. I currently > have four 3750's. Two belonging to one business unit and two belonging to > another. Each group of switches is running a separate VTP domain / VLAN > database. > > I am running PVST however when I connect the final link between the four > switches there is a loop and spanning tree doesn't block any of the ports. > Would anyone have any clue as to why this would be happening? Could it have > something to do with the link between the Business units being on separate > VLANs? We don't want the possibility of VLAN corruption occurring hence the > different VTP domains. Currently I am shutting down one of the uplink ports > to Business A to remedy this problem. Please see the diagram below. > > > > Cheers, > > > > ------------------------ ------------------------ > > | 3750 Switch 1 |------- Trunk ------ | 3750 Switch 2 | > > | Business A | | Business A | > > ------------------------- ------------------------- > > | VL 50 | VL 50 > > > | | > > | VL 100 | VL 100 > > > ------------------------ ------------------------ > > | 3750 Switch 3 |------- Trunk ------ | 3750 Switch 4 | > > | Business B | | Business B | > > ------------------------- ------------------------- > > > > > > Aaron. > > > > > > _______________________________________________ > cisco-nsp mailing list [email protected] > https://puck.nether.net/mailman/listinfo/cisco-nsp > archive at http://puck.nether.net/pipermail/cisco-nsp/ > Confidentiality Notice: This e-mail message (including any attached or embedded documents) is intended for the exclusive and confidential use of the individual or entity to which this message is addressed, and unless otherwise expressly indicated, is confidential and privileged information of Rackspace. Any dissemination, distribution or copying of the enclosed material is prohibited. If you receive this transmission in error, please notify us immediately by e-mail at [EMAIL PROTECTED], and delete the original message. Your cooperation is appreciated. _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
