STP in Packet Tracer

I use Packet Tracer to do some simple labs. Right now, I'm labbing STP and I can't figure this out.Here is a screenshot of what my setup looks like:

Running-config from Switch0 (cut for brevity):

spanning-tree mode rapid-pvst
spanning-tree vlan 1 priority 0
spanning-tree vlan 3 priority 24576
interface FastEthernet0/11
switchport access vlan 3

interface FastEthernet0/16
switchport mode trunk
switchport nonegotiate

interface FastEthernet0/17
switchport mode trunk
switchport nonegotiate

Running-config from Switch1:

spanning-tree mode rapid-pvst
spanning-tree vlan 3 priority 0
spanning-tree vlan 1 priority 20480

interface FastEthernet0/12
switchport access vlan 3

interface FastEthernet0/16
switchport mode trunk
switchport nonegotiate

interface FastEthernet0/17
switchport mode trunk
switchport nonegotiate

As you see, I have 2 VLANs on the switches (configured with VTP). However, I'm trying to use different root bridges on vlans.Here is what I get when I run show spanning-tree:

Switch0

VLAN0001

Spanning tree enabled protocol rstp

Root ID Priority 1

Address 0009.7C5A.25EA

This bridge is the root

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 1 (priority 0 sys-id-ext 1)

Address 0009.7C5A.25EA

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Aging Time 20

Interface Role Sts Cost Prio.Nbr Type

---- ---

Fa0/16 Desg FWD 19 128.16 P2p

Fa0/17 Desg FWD 19 128.17 P2p

VLAN0003

Spanning tree enabled protocol rstp

Root ID Priority 24579

Address 0009.7C5A.25EA

This bridge is the root

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 24579 (priority 24576 sys-id-ext 3)

Address 0009.7C5A.25EA

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Aging Time 20

Interface Role Sts Cost Prio.Nbr Type

---- ---

Fa0/11 Desg FWD 19 128.11 P2p

Fa0/16 Desg FWD 19 128.16 P2p

Fa0/17 Desg FWD 19 128.17 P2p

Switch1:
VLAN0001

Spanning tree enabled protocol rstp

Root ID Priority 20481

Address 0001.644D.2BB3

This bridge is the root

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 20481 (priority 20480 sys-id-ext 1)

Address 0001.644D.2BB3

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Aging Time 20

Interface Role Sts Cost Prio.Nbr Type

---- ---

Fa0/16 Desg FWD 19 128.16 P2p

Fa0/17 Desg FWD 19 128.17 P2p

VLAN0003

Spanning tree enabled protocol rstp

Root ID Priority 3

Address 0001.644D.2BB3

This bridge is the root

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 3 (priority 0 sys-id-ext 3)

Address 0001.644D.2BB3

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Aging Time 20

Interface Role Sts Cost Prio.Nbr Type

---- ---

Fa0/16 Desg FWD 19 128.16 P2p

Fa0/17 Desg FWD 19 128.17 P2p

Fa0/12 Desg FWD 19 128.12 P2p

According to the outputs, both switches act as root bridges on both VLANs. How is it possible? Is it a bug in Packet Tracer or am I doing something wrong?

Capture.JPG

Find more posts tagged with

Free for TechExams community: Cybersecurity salary guide

Compare cert salaries and plan your next career move

Button

Comments

NotHackingYou

It looks to me like the election isn't being held for some reason

NotHackingYou

Oh also don't you have to use pvst to be able to get different VLANS to have different port roles? Looks like you are using RSTP but I think you need PVST.

Edit: Also try typing in debug spanning-tree and then bouncing the interfaces. Observe the results in the console window for each switch.

sratakhin

I'm using Rapid-PVST as the first line in each run-config says.
Unfortunately, Packet Tracer doesn't support debugging

NotHackingYou

Could you post the results of a sh int for each switch?

carmelenigma

I just repeated the config in my own packet tracer and I got normal results. I just didnt include the nonegotiation statements because i didnt think they were needed.

NotHackingYou

carmelenigma wrote: »

I just repeated the config in my own packet tracer and I got normal results. I just didnt include the nonegotiation statements because i didnt think they were needed.

The config looks correct to me. I suspect a problem with the interface config or maybe he selected the wrong cable type in PT? It's easy to do.

sratakhin

I'm using crossover cables between the switches. The switches are 2960s.

Switch0#sh int fa0/16
FastEthernet0/16 is up, line protocol is up (connected)
Hardware is Lance, address is 0060.5c59.0010 (bia 0060.5c59.0010)
BW 100000 Kbit, DLY 1000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 100Mb/s
input flow-control is off, output flow-control is off
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:08, output 00:00:05, 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
956 packets input, 193351 bytes, 0 no buffer
Received 956 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
0 watchdog, 0 multicast, 0 pause input
0 input packets with dribble condition detected
2357 packets output, 263570 bytes, 0 underruns
0 output errors, 0 collisions, 10 interface resets
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier
0 output buffer failures, 0 output buffers swapped out

Switch0#sh int fa0/17
FastEthernet0/17 is up, line protocol is up (connected)
Hardware is Lance, address is 0060.5c59.0011 (bia 0060.5c59.0011)
BW 100000 Kbit, DLY 1000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 100Mb/s
input flow-control is off, output flow-control is off
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:08, output 00:00:05, 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
956 packets input, 193351 bytes, 0 no buffer
Received 956 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
0 watchdog, 0 multicast, 0 pause input
0 input packets with dribble condition detected
2357 packets output, 263570 bytes, 0 underruns
0 output errors, 0 collisions, 10 interface resets
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier
0 output buffer failures, 0 output buffers swapped out

___________________________________

Switch1#sh int f0/16
FastEthernet0/16 is up, line protocol is up (connected)
Hardware is Lance, address is 0006.2ac8.8410 (bia 0006.2ac8.8410)
BW 100000 Kbit, DLY 1000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 100Mb/s
input flow-control is off, output flow-control is off
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:08, output 00:00:05, 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
956 packets input, 193351 bytes, 0 no buffer
Received 956 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
0 watchdog, 0 multicast, 0 pause input
0 input packets with dribble condition detected
2357 packets output, 263570 bytes, 0 underruns
0 output errors, 0 collisions, 10 interface resets
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier
0 output buffer failures, 0 output buffers swapped out

Switch1#sh int f0/17
FastEthernet0/17 is up, line protocol is up (connected)
Hardware is Lance, address is 0006.2ac8.8411 (bia 0006.2ac8.8411)
BW 100000 Kbit, DLY 1000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 100Mb/s
input flow-control is off, output flow-control is off
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:08, output 00:00:05, 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
956 packets input, 193351 bytes, 0 no buffer
Received 956 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
0 watchdog, 0 multicast, 0 pause input
0 input packets with dribble condition detected
2357 packets output, 263570 bytes, 0 underruns
0 output errors, 0 collisions, 10 interface resets
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier
0 output buffer failures, 0 output buffers swapped out

carmelenigma

It looks like your lines are all up so cabling is good, how about a show run?

ccnxjr

Just curious,
Are those links to the PC's configured as trunks?
It's hard to tell how you got them cabled up, could be you have them plugged into mismatched ports?
Can't tell which port is connected to what from the picture.
Also, what version of packet tracer are you using?
I plugged your config into version 5.2.1.0008 and it seems to work.

sratakhin

Hm... I did some changes to the configurations and now it's working correctly. Wondering what caused it... The only thing that is different in running-config is that I no longer use switchport no-negotiate

The PCs are connected to access ports. I'm using PT 5.3.3

NotHackingYou

Could you also post a sh vtp and a sh run please?

NotHackingYou

Glad you got it going!

sratakhin

Thank you for the suggestion.
I'm trying to replicate the problem again and I can't

carmelenigma

maybe just a hiccup,it happens

sratakhin

I scratched my head for almost two hours... Guess I'd finally better invest in a real lab. Or just grab some ProCurves from work.

inscom.brigade

glad you got it,
but don't begin to think that it will get easyer with real lab gear; that is when the fun begins.

Most of us build labs on a budget=mismatched and undesirable components, inadiquite memory old stuff EOL/EOS, pc's,servers, not good enough all to offten.
AND what are we trying to emulate | ( latest technology enterprise/campus design) | #&^%$@! <- give yourself a break good job!