port mac address security might work, altho its a lot of admin overhead..are you running portfast bpdu-guard on the access ports?
Larry Letterman Network Engineer Cisco Systems ----- Original Message ----- From: Thomas N. To: [EMAIL PROTECTED] Sent: Tuesday, April 01, 2003 8:14 PM Subject: VLAN loop problem [7:66656] Hi All, I got a problem in the production campus LAN here between VLANs. Please help me out! Below is the scenario: We have VLAN 10 (10.10.x.x) and VLAN 20 (10.20.x.x) subnets. Routing is enable/allowed between the two subnets using MSFC of the 6500. Each subnet has a DHCP server to assign IP address to devices on its subnet. Spanning-tree is enable; however, portfast is turned on on all non-trunking/uplink ports. Recently, devices on VLAN 10 got assigned an IP address of 10.20.x.x , which is from the DHCP on the other scope and also from 10.10.x.x scope, and vice versa. It seems that we a loop somewhere between the 2 subnets but we don't know where. I noticed lots of end users have a little unmanged hub/switch hang off the network jacks in their cubicals and potentially cause loop. Is there any way that we can block the loop on the Cisco switches without visiting cubicals taking those little umanaged hubs/switches? Thanks! Thomas Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=66660&t=66656 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
