forum question i answered with examples...

Is it true that BPDU's are still sent out access ports ?

and if so can we prevent BPDU's being sent using BPDU filter ? also

if we what would happen if a switch was accidently attached to an access  port with BPDU filter enabled .

one more thing , is it best practice to enable BPDU filter or BPDU guard on all access ports ?

part 1)

yes... see debug output for fa0/17... xmit bpdu...

sw2950_02#sh run int fa0/17

Building configuration...

Current configuration : 85 bytes

!

interface FastEthernet0/17

switchport access vlan 10

switchport mode access

end

sw2950_02#debug spann bpdu trans

Spanning Tree BPDU Transmitted debugging is on

sw2950_02#

1d01h: STP: VLAN0010 Fa0/17 tx BPDU: config protocol=ieee

    Data : 0000 00 00 00 600A0009B752D780 00000013 800A0009B73FCE80 8011 0100 14

00 0200 0F00

part 2) 

bpdufilter turns bpdu xmit off for the interface... see below, fa0/17 is conspicuously missing...

sw2950_02(config-if)#spann bpdufilter enable

sw2950_02(config-if)#int fa0/17

sw2950_02(config-if)#spann bpdufilter enable

sw2950_02(config-if)#do sh run int fa0/17

Building configuration...

Current configuration : 118 bytes

!

interface FastEthernet0/17

switchport access vlan 10

switchport mode access

spanning-tree bpdufilter enable

end

sw2950_02#debug spann bpdu trans

Spanning Tree BPDU Transmitted debugging is on

sw2950_02#

1d01h: STP: VLAN0001 Fa0/2 tx BPDU: config protocol=ieee

    Data : 0000 00 00 00 80010009B73FCE80 00000000 80010009B73FCE80 8002 0000 14

00 0200 0F00

1d01h: STP: VLAN0020 Fa0/1 tx BPDU: config protocol=ieee

    Data : 0000 00 00 00 80140009B73FCE80 00000000 80140009B73FCE80 8001 0000 14

00 0200 0F00

1d01h: STP: VLAN0020 Fa0/2 tx BPDU: config protocol=ieee

    Data : 0000 00 00 00 80140009B73FCE80 00000000 80140009B73FCE80 8002 0000 14

00 0200 0F00

1d01h: STP: VLAN0050 Fa0/1 tx BPDU: config protocol=ieee

    Data : 0000 00 00 00 80320009B73FCE80 00000000 80320009B73FCE80 8001 0000 14

00 0200 0F00

1d01h: STP: VLAN0050 Fa0/2 tx BPDU: config protocol=ieee

    Data : 0000 00 00 00 80320009B73FCE80 00000000 80320009B73FCE80 8002 0000 14

00 0200 0F00

1d01h: STP: VLAN0050 Fa0/15 tx BPDU: config protocol=ieee

    Data : 0000 00 00 00 80320009B73FCE80 00000000 80320009B73FCE80 800F 0000 14

00 0200 0F00

1d01h: STP: VLAN0050 Fa0/16 tx BPDU: config protocol=ieee

    Data : 0000 00 00 00 80320009B73FCE80 00000000 80320009B73FCE80 8010 0000 14

00 0200 0F00

1d01h: STP: VLAN0010 Fa0/18 tx BPDU: config protocol=ieee

    Data : 0000 00 00 00 600A0009B752D780 00000013 800A0009B73FCE80 8012 0100 14

00 0200 0F00

sw2950_02#

1d01h: STP: VLAN0010 Fa0/19 tx BPDU: config protocol=ieee

    Data : 0000 00 00 00 600A0009B752D780 00000013 800A0009B73FCE80 8013 0100 14

00 0200 0F00

part 3)

when i attached a switch to the bpdufilter enabled port, the port blinked amber/green, and basically the switch stopped functioning correctly... in fact the entire switch freaked out... doesn't seem like a good idea...

part 4)

bpduguard and portfast are considered best practice for access ports...

my switched network for the good of all mankind...