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I'm still a beginner with VLANs and trunking, and I'm trying to get this topology working. Specifically, I am unable to ping PC4 (10.0.10.11/32) from PC1 (10.0.10.10/32), despite both of them being on VLAN 10.

I believe I have set up the appropriate switchports with mode access and the trunking ports between Switches 1 and 3, and Switches 2 and 3 respectively. I have not set up IP-addressing on any of the interfaces or the VLANs as I don't think it is necessary.

I will now present the text outputs for each of the switches. Each of these combines the running config, show vlan brief and show interfaces trunk command.

Switch 1:


SW-1#show running-config 
Building configuration...

Current configuration : 1516 bytes
!
version 12.2
no service timestamps log datetime msec
no service timestamps debug datetime msec
no service password-encryption
!
hostname SW-1
!
!
!
!
!
!
spanning-tree mode pvst
spanning-tree extend system-id
!
interface FastEthernet0/1
 switchport access vlan 10
 switchport mode access
!
interface FastEthernet0/2
 switchport access vlan 20
 switchport mode access
!
interface FastEthernet0/3
 switchport access vlan 30
 switchport mode access
!
interface FastEthernet0/4
 switchport access vlan 40
 switchport mode access
!
interface FastEthernet0/5
 switchport access vlan 50
 switchport mode access
!
interface FastEthernet0/6
 switchport mode trunk
!
interface FastEthernet0/7
!
interface FastEthernet0/8
!
interface FastEthernet0/9
!
interface FastEthernet0/10
!
interface FastEthernet0/11
!
interface FastEthernet0/12
!
interface FastEthernet0/13
!
interface FastEthernet0/14
!
interface FastEthernet0/15
!
interface FastEthernet0/16
!
interface FastEthernet0/17
!
interface FastEthernet0/18
!
interface FastEthernet0/19
!
interface FastEthernet0/20
!
interface FastEthernet0/21
!
interface FastEthernet0/22
!
interface FastEthernet0/23
!
interface FastEthernet0/24
!
interface GigabitEthernet0/1
!
interface GigabitEthernet0/2
!
interface Vlan1
 no ip address
!
interface Vlan10
 no ip address
!
interface Vlan20
 no ip address
!
interface Vlan30
 no ip address
!
interface Vlan40
 no ip address
!
interface Vlan50
 no ip address
!
!
!
!
line con 0
!
line vty 0 4
 login
line vty 5 15
 login
!
!
!
!
end

SW-1#sho vlan br

VLAN Name                             Status    Ports

1    default                          active    Fa0/7, Fa0/8, Fa0/9, Fa0/10
                                                Fa0/11, Fa0/12, Fa0/13, Fa0/14
                                                Fa0/15, Fa0/16, Fa0/17, Fa0/18
                                                Fa0/19, Fa0/20, Fa0/21, Fa0/22
                                                Fa0/23, Fa0/24, Gig0/1, Gig0/2
10   VLAN0010                         active    Fa0/1
20   VLAN0020                         active    Fa0/2
30   VLAN0030                         active    Fa0/3
40   VLAN0040                         active    Fa0/4
50   VLAN0050                         active    Fa0/5
1002 fddi-default                     active    
1003 token-ring-default               active    
1004 fddinet-default                  active    
1005 trnet-default                    active   

SW-1#show interfaces trunk 
Port        Mode         Encapsulation  Status        Native vlan
Fa0/6       on           802.1q         trunking      1

Port        Vlans allowed on trunk
Fa0/6       1-1005

Port        Vlans allowed and active in management domain
Fa0/6       1,10,20,30,40,50

Port        Vlans in spanning tree forwarding state and not pruned
Fa0/6       1,10,20,30,40,50
}
____________________________

Switch 2:

SW-2(config-if)#do show running-config
Building configuration...

Current configuration : 1529 bytes
!
version 12.2
no service timestamps log datetime msec
no service timestamps debug datetime msec
no service password-encryption
!
hostname SW-2
!
!
!
!
!
!
spanning-tree mode pvst
spanning-tree extend system-id
!
interface FastEthernet0/1
 switchport access vlan 10
 switchport mode access
!
interface FastEthernet0/2
 switchport access vlan 20
 switchport mode access
!
interface FastEthernet0/3
 switchport access vlan 30
 switchport mode access
!
interface FastEthernet0/4
 switchport access vlan 60
 switchport mode access
!
interface FastEthernet0/5
 switchport access vlan 99
 switchport mode access
!
interface FastEthernet0/6
 switchport mode trunk
!
interface FastEthernet0/7
!
interface FastEthernet0/8
!
interface FastEthernet0/9
!
interface FastEthernet0/10
!
interface FastEthernet0/11
!
interface FastEthernet0/12
!
interface FastEthernet0/13
!
interface FastEthernet0/14
!
interface FastEthernet0/15
!
interface FastEthernet0/16
!
interface FastEthernet0/17
!
interface FastEthernet0/18
!
interface FastEthernet0/19
!
interface FastEthernet0/20
!
interface FastEthernet0/21
!
interface FastEthernet0/22
!
interface FastEthernet0/23
!
interface FastEthernet0/24
!
interface GigabitEthernet0/1
!
interface GigabitEthernet0/2
 duplex half
!
interface Vlan1
 no ip address
!
interface Vlan10
 no ip address
!
interface Vlan20
 no ip address
!
interface Vlan30
 no ip address
!
interface Vlan60
 no ip address
!
interface Vlan99
 no ip address
!
!
!
!
line con 0
!
line vty 0 4
 login
line vty 5 15
 login
!
!
!
!
end

SW-2#sho vl br

VLAN Name                             Status    Ports

1    default                          active    Fa0/7, Fa0/8, Fa0/9, Fa0/10
                                                Fa0/11, Fa0/12, Fa0/13, Fa0/14
                                                Fa0/15, Fa0/16, Fa0/17, Fa0/18
                                                Fa0/19, Fa0/20, Fa0/21, Fa0/22
                                                Fa0/23, Fa0/24, Gig0/1, Gig0/2
10   VLAN0010                         active    Fa0/1
20   VLAN0020                         active    Fa0/2
30   VLAN0030                         active    Fa0/3
60   VLAN0060                         active    Fa0/4
99   VLAN0099                         active    Fa0/5
1002 fddi-default                     active    
1003 token-ring-default               active    
1004 fddinet-default                  active    
1005 trnet-default                    active  

SW-2# show interfaces trunk
Port        Mode         Encapsulation  Status        Native vlan
Fa0/6       on           802.1q         trunking      1

Port        Vlans allowed on trunk
Fa0/6       1-1005

Port        Vlans allowed and active in management domain
Fa0/6       1,10,20,30,60,99

Port        Vlans in spanning tree forwarding state and not pruned
Fa0/6       1,10,20,30,60,99

__________________________

Switch 3:

SW-3(config)#do show running-config
Building configuration...

Current configuration : 1114 bytes
!
version 12.2
no service timestamps log datetime msec
no service timestamps debug datetime msec
no service password-encryption
!
hostname SW-3
!
!
!
!
!
!
spanning-tree mode pvst
spanning-tree extend system-id
!
interface FastEthernet0/1
 switchport mode trunk
!
interface FastEthernet0/2
 switchport mode trunk
!
interface FastEthernet0/3
!
interface FastEthernet0/4
!
interface FastEthernet0/5
!
interface FastEthernet0/6
!
interface FastEthernet0/7
!
interface FastEthernet0/8
!
interface FastEthernet0/9
!
interface FastEthernet0/10
!
interface FastEthernet0/11
!
interface FastEthernet0/12
!
interface FastEthernet0/13
!
interface FastEthernet0/14
!
interface FastEthernet0/15
!
interface FastEthernet0/16
!
interface FastEthernet0/17
!
interface FastEthernet0/18
!
interface FastEthernet0/19
!
interface FastEthernet0/20
!
interface FastEthernet0/21
!
interface FastEthernet0/22
!
interface FastEthernet0/23
!
interface FastEthernet0/24
!
interface GigabitEthernet0/1
!
interface GigabitEthernet0/2
!
interface Vlan1
 no ip address
!
!
!
!
line con 0
!
line vty 0 4
 login
line vty 5 15
 login
!
!
!
!
end


SW-3(config)#exit
SW-3#
%SYS-5-CONFIG_I: Configured from console by console

SW-3#sho vl br

VLAN Name                             Status    Ports

1    default                          active    Fa0/3, Fa0/4, Fa0/5, Fa0/6
                                                Fa0/7, Fa0/8, Fa0/9, Fa0/10
                                                Fa0/11, Fa0/12, Fa0/13, Fa0/14
                                                Fa0/15, Fa0/16, Fa0/17, Fa0/18
                                                Fa0/19, Fa0/20, Fa0/21, Fa0/22
                                                Fa0/23, Fa0/24, Gig0/1, Gig0/2
1002 fddi-default                     active    
1003 token-ring-default               active    
1004 fddinet-default                  active    
1005 trnet-default                    active    


SW-3#show interfaces trunk 
Port        Mode         Encapsulation  Status        Native vlan
Fa0/1       on           802.1q         trunking      1
Fa0/2       on           802.1q         trunking      1

Port        Vlans allowed on trunk
Fa0/1       1-1005
Fa0/2       1-1005

Port        Vlans allowed and active in management domain
Fa0/1       1
Fa0/2       1

Port        Vlans in spanning tree forwarding state and not pruned
Fa0/1       1
Fa0/2       1

_______________________________

I would be grateful for any help. I can generate any additional info as required. Thanks so much in advance.

EDIT: Adding on the outputs of the show spanning-tree VLAN 10 commands for each of the switches as advised by Ron Trunk. The output for Switch 3 looks suspiciously short.

Switch 1:

SW-1#sho spanning-tree vlan 10
VLAN0010
  Spanning tree enabled protocol ieee
  Root ID    Priority    32778
             Address     0060.2F6E.6029
             This bridge is the root
             Hello Time  2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    32778  (priority 32768 sys-id-ext 10)
             Address     0060.2F6E.6029
             Hello Time  2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time  20

Interface        Role Sts Cost      Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa0/1            Desg FWD 19        128.1    P2p
Fa0/6            Desg FWD 19        128.6    P2p

Switch 2:

    SW-2#sho spanning-tree vlan 10
VLAN0010
  Spanning tree enabled protocol ieee
  Root ID    Priority    32778
             Address     0090.2BD9.91EA
             This bridge is the root
             Hello Time  2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    32778  (priority 32768 sys-id-ext 10)
             Address     0090.2BD9.91EA
             Hello Time  2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time  20

Interface        Role Sts Cost      Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa0/6            Desg FWD 19        128.6    P2p
Fa0/1            Desg FWD 19        128.1    P2p

Switch 3:

SW-3#sho spanning-tree vlan 10

No spanning tree instance exists.
Improve this question
5
  • Thanks so much for the edit Ron. Love your last name lol. :)
    – Deepak
    Commented May 16, 2022 at 12:56
  • You're welcome. Nothing jumps out at me. Please include show spanning-tree vlan 10 on each switch.
    – Ron Trunk
    Commented May 16, 2022 at 12:58
  • @RonTrunk I am unfamiliar with this command (still a noob), but I've done as you've asked. I'm sorry, I tried using the pre-formatted text following your example, but it wasn't perfect. Please excuse this. The output for Switch 3 looks suspiciously concise.
    – Deepak
    Commented May 16, 2022 at 13:07
  • Please include in your question which ports are used to connect PC1, PC4, SW1-SW3, SW2-SW3.
    – Zac67 ♦
    Commented May 16, 2022 at 13:20
  • @Zac67 Thanks, Ron's answer solved my issue. I really appreciate the help. :)
    – Deepak
    Commented May 16, 2022 at 13:44

1 Answer 1

Reset to default
2

You have not created the VLANs on Switch 3.
You must create the VLAN before you can assign ports to it.

On Switch 3:

Vlan 10
name myvlan
exit
Improve this answer
1
  • This immediately solved my issue! Thanks so much. It was a misconception that I had that trunking alone was enough for switch 3, as I thought trunks allow tagged and untagged traffic through without issues. Now I know better. Thanks so much!
    – Deepak
    Commented May 16, 2022 at 13:43

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