04-16-2003 11:10 PM - edited 03-02-2019 06:44 AM
Hello All!
I try to disable VTP on Catalyst 2950 [ IOS (tm) C2950 Software (C2950-I6Q4L2-M), Version 12.1(13)EA1 ] :
WS2950-12(config)#vtp mode transparent
WS2950-12#show vtp status
VTP Version : 2
Configuration Revision : 0
Maximum VLANs supported locally : 64
Number of existing VLANs : 8
VTP Operating Mode : Transparent
VTP Domain Name :
VTP Pruning Mode : Disabled
VTP V2 Mode : Disabled
VTP Traps Generation : Disabled
Seems to be ok? Lets see.
WS2950-12#show run interface fastEthernet 0/3
interface FastEthernet0/3
switchport access vlan 3
no cdp enable
spanning-tree portfast
WS2950-12#show interfaces fastEthernet 0/3
FastEthernet0/3 is up, line protocol is up (connected)
Hardware is Fast Ethernet, address is 0007.8431.4883
<last skipped>
I connect to port 3 sniffer (tcpdump):
<time> 0:7:84:31:48:83 1:0:c:cc:cc:cc 002c 60: sap aa ui/C len=35
<hex data skipped>
<time> 0:7:84:31:48:83 1:0:c:0:0:0 8100 94: 802.1Q vlan#1 P7 sap aa ui/C len=65
<hex data skipped>
I see some traffic with Source_MAC of my WS2950-12. And as far as I understand this traffic is a part of VTP (Ethernet_SNAP, OUI= 00:00:0C, OUI belongs to Cisco).
Where is my mistake or How can I disable VTP on 2950 really?
Thanks!
PS. Disabling VTP on 2900XL with similar configuration does not cause a problem.
04-16-2003 11:49 PM
Hi,
AFAIK, VTP transparent doesn't turn off VTP process on the switch.
The switch is still looking at the VTP frames and forwarding them.
In VTP ver.1 VTP frames are forwarded only if VTP domain name and version matches, VTP ver. 2 doesn't provide this version check.
VTP frames are not forwarded by normal bridging procedures.
BUT VTP frames should not be forwarded on access ports at all!!
If you want to disable VTP you can use set vtp mode off. But this command is available since CatOS 7.5(1) and is not available on IOS based switches yet.
Regards,
Milan
04-17-2003 04:02 AM
In my opinion I've made significant downgrade of software (C2950-C3H2S-M, Version 12.0(5)WC2b) and problem disappear.
I've tested c2950-i6q4l2-mz.121-12c.EA1.bin and c2950-i6q4l2-mz.121-9.EA1d.bin - they are affected by this bug too :(
People who wish may easy reproduce and report a bug :)
Thanks!
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