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TOPIC: Catalyst 2960G - Vlan Keep Changing

Catalyst 2960G - Vlan Keep Changing 9 years 3 months ago #32690

  • apit
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I have about 50 unit cisco access switch model Catalyst 2960G...Details for the IOS as below :

Cisco IOS Software, C2960 Software (C2960-LANBASE-M), Version 12.2(35)SE5, RELEASE SOFTWARE (fc1)
Copyright (c) 1986-2007 by Cisco Systems, Inc.
Compiled Thu 19-Jul-07 20:06 by nachen
Image text-base: 0x00003000, data-base: 0x00D40000

ROM: Bootstrap program is C2960 boot loader
BOOTLDR: C2960 Boot Loader (C2960-HBOOT-M) Version 12.2(25r)SEE6, RELEASE SOFTWARE (fc1)

The problem was :

- 1 unit of the switch automatically change it port vlan ; from switch port access mode to trunk mode

- 2 unit of the switch automatically change it's vlan ID(400) to the old ID (140).

Security Part :

- All the switches is protected with password
- Only 1 pc(IP) is allowed to telnet to all the switches. Others IP is blocked by the ACL.

Switch Uptime :

- The switch uptime is more than 1 month and the problem occur last 2 days. All the switch configuration have been save after change to new vlan ID.

Need advice from all of you guys..


Re: Catalyst 2960G - Vlan Keep Changing 9 years 3 months ago #32695

did u try to turn DTP off by using "switchport nonegotiate" command coz some internetworking devices might forward DTP frames improperly, which cause misconfigurations.
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