05-29-2018 09:44 AM - edited 03-05-2019 10:31 AM
I have a 3750 Stack on my network with several VLANs. One of these VLANs is 100.
I configured a switch that is also using vlan 100 on every port. I plug a cable from a port on my stack to the newly configured switch with nothing else plugged into that new switch and I get Unexpected BPDU packet on the stack and the port is shut down.
FastEthernet1/0/2 is down, line protocol is down (err-disabled)
Hardware is Fast Ethernet, address is 0013.7f0c.1c04 (bia 0013.7f0c.1c04)
Description: None
MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Auto-duplex, Auto-speed, media type is 10/100BaseTX
input flow-control is off, output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:15, output never, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
9 packets input, 1507 bytes, 0 no buffer
Received 6 broadcasts (6 multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 6 multicast, 0 pause input
0 input packets with dribble condition detected
37 packets output, 4730 bytes, 0 underruns
0 output errors, 0 collisions, 6 interface resets
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier, 0 PAUSE output
0 output buffer failures, 0 output buffers swapped out
On the New Switch it says
FastEthernet0/1 is down, line protocol is down (notconnect)
Hardware is Fast Ethernet, address is 0011.5c00.3101 (bia 0011.5c00.3101)
MTU 1522 bytes, BW 100000 Kbit, DLY 100 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Auto-duplex, Auto-speed, media type is 10/100BaseTX
input flow-control is off, output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:04:28, output 00:04:27, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
22 packets input, 2492 bytes, 0 no buffer
Received 22 broadcasts (0 multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 8 multicast, 0 pause input
0 input packets with dribble condition detected
6 packets output, 1004 bytes, 0 underruns
0 output errors, 0 collisions, 1 interface resets
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier, 0 PAUSE output
0 output buffer failures, 0 output buffers swapped out
Nothing else is plugged into that switch I just connected. Any idea why I am getting this?
05-29-2018 10:26 AM
It sounds like the new switch sent a spanning tree BPDU on its port, which would be expected behavior if it is configured as a normal access port. It sounds like the 3750 did not expect to receive a BPDU. Can you post config of the 3750 (at least the config of the interface and of show run | inc span).
HTH
Rick
05-29-2018 10:47 AM - edited 05-29-2018 10:47 AM
interface FastEthernet1/0/2
description 100
switchport access vlan 100
switchport mode access
spanning-tree portfast
Is this what you are looking for?
05-29-2018 11:54 AM
That is the configuration of the interface and it looks quite normal. Could you also post the output of these commands
show run | inc span
show spanning-tree
I am wondering if something like BPDUGUARD is enabled.
HTH
Rick
05-29-2018 12:50 PM
Here is the output with the commands specified:
show run | inc span
spanning-tree mode mst
spanning-tree portfast bpduguard default
no spanning-tree optimize bpdu transmission
spanning-tree extend system-id
spanning-tree backbonefast
spanning-tree mst configuration
spanning-tree mst 1 priority 24576
no spanning-tree vlan 34,100
spanning-tree portfast
spanning-tree portfast
spanning-tree portfast
spanning-tree portfast
spanning-tree portfast
spanning-tree portfast
spanning-tree portfast
spanning-tree portfast
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show spanning-tree
MST0
Spanning tree enabled protocol mstp
Root ID Priority 0
Address 2880.2346.9460
Cost 220000
Port 135 (GigabitEthernet3/1/3)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32768 (priority 32768 sys-id-ext 0)
Address 001e.13a1.ee80
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Gi2/0/1 Desg FWD 20000 128.55 P2p Edge
Fa2/0/2 Desg FWD 200000 128.58 P2p Edge
Fa2/0/4 Desg FWD 200000 128.60 P2p Edge
Fa2/0/7 Desg FWD 200000 128.63 P2p Edge
Fa2/0/8 Desg FWD 200000 128.64 P2p Edge
Fa2/0/10 Desg FWD 200000 128.66 P2p Edge
Fa2/0/11 Desg FWD 200000 128.67 P2p Edge
Fa2/0/12 Desg FWD 200000 128.68 P2p Edge
Fa2/0/13 Desg FWD 200000 128.69 P2p Edge
Fa2/0/18 Desg FWD 200000 128.74 P2p Edge
Fa2/0/20 Desg FWD 200000 128.76 P2p Edge
Fa2/0/22 Desg FWD 200000 128.78 P2p Edge
Fa2/0/25 Desg FWD 200000 128.83 P2p Edge
Fa2/0/27 Desg FWD 200000 128.85 P2p Edge
Fa2/0/30 Desg FWD 200000 128.88 P2p Edge
Fa2/0/31 Desg FWD 200000 128.89 P2p Edge
Fa2/0/35 Desg FWD 200000 128.93 P2p Edge
Fa2/0/36 Desg FWD 200000 128.94 P2p Edge
Fa2/0/38 Desg FWD 200000 128.96 P2p Edge
Fa2/0/40 Desg FWD 200000 128.98 P2p Edge
Fa2/0/41 Desg FWD 200000 128.99 P2p Edge
Fa2/0/42 Desg FWD 200000 128.100 P2p Edge
Gi1/0/1 Desg FWD 20000 128.1 P2p Edge
Fa1/0/2 Desg FWD 200000 128.4 P2p Bound(STP)
Fa1/0/8 Desg FWD 200000 128.10 P2p Edge
Fa1/0/9 Desg FWD 200000 128.11 P2p Edge
Fa1/0/11 Desg FWD 200000 128.13 P2p Edge
Fa1/0/12 Desg FWD 200000 128.14 P2p Edge
Fa1/0/13 Desg FWD 200000 128.15 P2p Edge
Fa1/0/16 Desg FWD 200000 128.18 P2p Edge
Fa1/0/18 Desg FWD 200000 128.20 P2p Edge
Fa1/0/19 Desg FWD 200000 128.21 P2p Edge
Fa1/0/20 Desg FWD 200000 128.22 P2p Edge
Gi1/0/3 Desg FWD 20000 128.27 P2p Edge
Gi1/0/4 Desg FWD 20000 128.28 P2p Edge
Fa1/0/26 Desg FWD 200000 128.30 P2p Edge
Fa1/0/27 Desg FWD 200000 128.31 P2p Edge
Fa1/0/31 Desg FWD 200000 128.35 P2p Edge
Fa1/0/38 Desg FWD 200000 128.42 P2p Edge
Fa1/0/39 Desg FWD 200000 128.43 P2p Edge
Fa1/0/42 Desg FWD 200000 128.46 P2p Edge
Fa1/0/43 Desg FWD 200000 128.47 P2p Edge
Fa1/0/46 Desg FWD 200000 128.50 P2p Edge
Gi3/0/1 Desg FWD 20000 128.109 P2p
Gi3/0/2 Desg FWD 20000 128.110 P2p Edge
Gi3/0/5 Desg FWD 20000 128.113 P2p Edge
Gi3/0/6 Desg FWD 200000 128.114 P2p Edge
Gi3/0/7 Desg FWD 20000 128.115 P2p Edge
Gi3/0/8 Desg FWD 200000 128.116 P2p Edge
Gi3/0/9 Desg FWD 20000 128.117 P2p Edge
Gi3/0/11 Desg FWD 20000 128.119 P2p Edge
Gi3/0/12 Desg FWD 20000 128.120 P2p Edge
Gi3/0/13 Desg FWD 20000 128.121 P2p Edge
Gi3/0/14 Desg FWD 20000 128.122 P2p Edge
Gi3/0/15 Desg FWD 20000 128.123 P2p Edge
Gi3/0/16 Desg FWD 20000 128.124 P2p Edge
Gi3/0/17 Desg FWD 20000 128.125 P2p
Gi3/0/18 Desg FWD 20000 128.126 P2p
Gi3/0/19 Desg FWD 20000 128.127 P2p Edge
Gi3/0/20 Desg FWD 200000 128.128 P2p Edge
Gi3/0/21 Desg FWD 20000 128.129 P2p
Gi3/0/22 Desg FWD 20000 128.130 P2p
Gi3/0/23 Desg FWD 20000 128.131 P2p
Gi3/0/24 Desg FWD 20000 128.132 P2p
Gi3/1/1 Desg FWD 20000 128.133 P2p
Gi3/1/3 Root FWD 20000 128.135 P2p
Gi3/1/4 Desg FWD 20000 128.136 P2p
MST1
Spanning tree enabled protocol mstp
Root ID Priority 24577
Address 001e.13a1.ee80
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 24577 (priority 24576 sys-id-ext 1)
Address 001e.13a1.ee80
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Gi2/0/1 Desg FWD 20000 128.55 P2p Edge
Fa2/0/2 Desg FWD 200000 128.58 P2p Edge
Fa2/0/4 Desg FWD 200000 128.60 P2p Edge
Fa2/0/7 Desg FWD 200000 128.63 P2p Edge
Fa2/0/8 Desg FWD 200000 128.64 P2p Edge
Fa2/0/10 Desg FWD 200000 128.66 P2p Edge
Fa2/0/11 Desg FWD 200000 128.67 P2p Edge
Fa2/0/12 Desg FWD 200000 128.68 P2p Edge
Fa2/0/13 Desg FWD 200000 128.69 P2p Edge
Fa2/0/18 Desg FWD 200000 128.74 P2p Edge
Fa2/0/20 Desg FWD 200000 128.76 P2p Edge
Fa2/0/22 Desg FWD 200000 128.78 P2p Edge
Fa2/0/25 Desg FWD 200000 128.83 P2p Edge
Fa2/0/27 Desg FWD 200000 128.85 P2p Edge
Fa2/0/30 Desg FWD 200000 128.88 P2p Edge
Fa2/0/31 Desg FWD 200000 128.89 P2p Edge
Fa2/0/35 Desg FWD 200000 128.93 P2p Edge
Fa2/0/36 Desg FWD 200000 128.94 P2p Edge
Fa2/0/38 Desg FWD 200000 128.96 P2p Edge
Fa2/0/40 Desg FWD 200000 128.98 P2p Edge
Fa2/0/41 Desg FWD 200000 128.99 P2p Edge
Fa2/0/42 Desg FWD 200000 128.100 P2p Edge
Gi1/0/1 Desg FWD 20000 128.1 P2p Edge
Fa1/0/2 Desg FWD 200000 128.4 P2p Bound(STP)
Fa1/0/8 Desg FWD 200000 128.10 P2p Edge
Fa1/0/9 Desg FWD 200000 128.11 P2p Edge
Fa1/0/11 Desg FWD 200000 128.13 P2p Edge
Fa1/0/12 Desg FWD 200000 128.14 P2p Edge
Fa1/0/13 Desg FWD 200000 128.15 P2p Edge
Fa1/0/16 Desg FWD 200000 128.18 P2p Edge
Fa1/0/18 Desg FWD 200000 128.20 P2p Edge
Fa1/0/19 Desg FWD 200000 128.21 P2p Edge
Fa1/0/20 Desg FWD 200000 128.22 P2p Edge
Gi1/0/3 Desg FWD 20000 128.27 P2p Edge
Gi1/0/4 Desg FWD 20000 128.28 P2p Edge
Fa1/0/26 Desg FWD 200000 128.30 P2p Edge
Fa1/0/27 Desg FWD 200000 128.31 P2p Edge
Fa1/0/31 Desg FWD 200000 128.35 P2p Edge
Fa1/0/38 Desg FWD 200000 128.42 P2p Edge
Fa1/0/39 Desg FWD 200000 128.43 P2p Edge
Fa1/0/42 Desg FWD 200000 128.46 P2p Edge
Fa1/0/43 Desg FWD 200000 128.47 P2p Edge
Fa1/0/46 Desg FWD 200000 128.50 P2p Edge
Gi3/0/1 Desg FWD 20000 128.109 P2p
Gi3/0/2 Desg FWD 20000 128.110 P2p Edge
Gi3/0/5 Desg FWD 20000 128.113 P2p Edge
Gi3/0/6 Desg FWD 200000 128.114 P2p Edge
Gi3/0/7 Desg FWD 20000 128.115 P2p Edge
Gi3/0/8 Desg FWD 200000 128.116 P2p Edge
Gi3/0/9 Desg FWD 20000 128.117 P2p Edge
Gi3/0/11 Desg FWD 20000 128.119 P2p Edge
Gi3/0/12 Desg FWD 20000 128.120 P2p Edge
Gi3/0/13 Desg FWD 20000 128.121 P2p Edge
Gi3/0/14 Desg FWD 20000 128.122 P2p Edge
Gi3/0/15 Desg FWD 20000 128.123 P2p Edge
Gi3/0/16 Desg FWD 20000 128.124 P2p Edge
Gi3/0/17 Desg FWD 20000 128.125 P2p
Gi3/0/18 Desg FWD 20000 128.126 P2p
Gi3/0/19 Desg FWD 20000 128.127 P2p Edge
Gi3/0/20 Desg FWD 200000 128.128 P2p Edge
Gi3/0/21 Desg FWD 20000 128.129 P2p
Gi3/0/22 Desg FWD 20000 128.130 P2p
Gi3/0/23 Desg FWD 20000 128.131 P2p
Gi3/0/24 Desg FWD 20000 128.132 P2p
Gi3/1/1 Desg FWD 20000 128.133 P2p
Gi3/1/3 Desg FWD 20000 128.135 P2p
Gi3/1/4 Desg FWD 20000 128.136 P2p
05-29-2018 12:52 PM
I typed in
no spanning-tree portfast
that made the problem go away. I am not sure that is the best solution though.
05-29-2018 01:33 PM
If you typed that in on just the port connecting to the switch stack then that is the correct thing to do.
You should not have portfast enabled on any ports that interconnect switches.
Jon
05-30-2018 06:18 AM
Thanks for the outputs. They do confirm that I was on the right track and that bpduguard is enabled.
spanning-tree portfast bpduguard default
I agree with Jon that disabling it on that particular interface is the correct solution.
HTH
Rick
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