our switch has been configured PVST with dot1q encapsulation on trunk port....
Since PVST is incampatable with dot1q encapsulation, how this switch has been working from long time?
Please need your valuable inputs...
i think this link will help you more:
If your referring to PVST+ in CAT0s/IOS, then it does work with Dot1Q.
Dot1Q is a trunking protocol encasulation, and just provides a common pipe for vlan traffic.
PVST+ is a spanning tree protocol that prevents L2 loops.
See the following ref:
I am using PVST not PVST+...
My question is why PVST is working with dot1q?
In our switch network someone by mistakenly configured PVST on a switch and on its trunk port is configured as a dot1q encapsulation...how come its layer 2 connectivity is up when PVST is incompatable with dot1q encapsulation
On switches, PVST was enhanced to PVST+ as soon as Cisco supported 802.1Q. So you cannot be running PVST on dot1Q trunk, that is necessarily PVST+.
When you say that PVST is not compatible with 802.1Q, is it just a theoric question or do you have a particular problem you want to share with the group?
I have attached show spanning-tree and show runn output....please advice
here is the show version
System returned to ROM by power-on
System image file is "flash:/c2950-i6q4l2-mz.121-14.EA1a.bin"
cisco WS-C2950G-24-EI (RC32300) processor (revision H0) with 20710K bytes of mem
Processor board ID FOC0803W1T9
Last reset from system-reset
Running Enhanced Image
24 FastEthernet/IEEE 802.3 interface(s)
2 Gigabit Ethernet/IEEE 802.3 interface(s)
32K bytes of flash-simulated non-volatile configuration memory.
Base ethernet MAC Address: 00:0F:23:96:8A:40
Motherboard assembly number: 73-7280-05
Power supply part number: 34-0965-01
Motherboard serial number: FOC08032979
Power supply serial number: DAB08020HAX
Model revision number: H0
Motherboard revision number: A0
Model number: WS-C2950G-24-EI
System serial number: FOC0803W1T9
Configuration register is 0xF