vlan trunking issue

[An19]

hi I'm trying to ping from pc 10.1 to pc 10.2 on the same VLAN 10
but it kept failing

I'm using VLAN 100 for Trunk. Please help me

[M02@rt37]

Hello @An19 

You need to allow  vlan 10 on your Trunk.

on Trunk ports:

switchport trunk allowed vlan 10

[An19]

hi, I just did what you suggested but it's not working. 

1. Multilayer Switch does not have the VLAN indicated on the IEEE 802.1q frame tag. It drops the frame. [from CoreSwitch]

and I think that the problem lies on my CoreSwitch, which I have not figuring out yet

[M02@rt37]

Ok @An19 

Ensure that vlan id 10 is configured. Check if vlan 10 is allowed on Trunk ports.

#show vlan brief 

#show interface trunk

[marce1000]

          - FYI! : Community group for Packet Tracer project questions

  M.

[Sharanjeet_Kumar]

You have keep following things on mind
1. You should configure trunk on uplink 
2. Need to allow vlan 10 on trunk
3. if you are making access ports to the uplinks, you need to do for vlan 10 
4. need to configure access port vlan 10 on both 10.1 and 10.2
Confirm above thing you will be able to 

Hope it helps!!!!

[vishalbhandari]

To troubleshoot the connectivity issue between the two PCs on the same VLAN, follow these steps:

       Check VLAN Assignment

• PCs: Ensure that both PCs (10.1 and 10.2) are correctly assigned to VLAN 10 on their respective switch ports.
• Switch Ports: Verify that the switch ports where the PCs are connected are configured as access ports and are assigned to VLAN 10.

  Verify Trunk Configuration

  • Trunk Ports: Ensure that the trunk ports between switches are correctly configured to carry VLAN 10 traffic. Also, make sure that VLAN 10 is allowed on the trunk.

    Check VLAN Status

    • VLAN Existence: Verify that VLAN 10 exists and is active on the switch.

      Check IP Configuration

      • PC IP Settings: Confirm that both PCs have IP addresses within the same subnet (e.g., 10.1.0.x/24) and correct subnet masks.
      • Default Gateway: Verify that both PCs have the correct default gateway configured, if required for communication beyond their subnet.

      Check for Port Security

      • Port Security Settings: If port security is configured on the switch ports, make sure it’s not blocking the PCs from communicating due to violations.

[Joseph W. Doherty]

I've see your problem and with the correct change:

Although your (trunk) interface configs are less than "ideal", they are not the problem.

Examine the following:

Switch1:

Switch#sh vlan b

VLAN Name                             Status    Ports
---- -------------------------------- --------- -------------------------------
1    default                          active    Fa0/1, 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, Gig0/2
10   K.CNTT                           active    Fa0/2
20   K.CLC                            active    Fa0/3
30   P.DT                             active    Fa0/4
40   WiFi                             active    
100  NATIVE                           active    

Switch0:

Switch>sh vlan b

VLAN Name                             Status    Ports
---- -------------------------------- --------- -------------------------------
1    default                          active    Fa0/1, 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
10   K.CNTT                           active    Fa0/2
20   K.CLC                            active    Fa0/3
30   P.DT                             active    Fa0/4
100  TRUNKING                         active    

Core Switch:

CoreSwitch#sh vlan b

VLAN Name                             Status    Ports
---- -------------------------------- --------- -------------------------------
1    default                          active    Fa0/2, Fa0/3, Fa0/4, 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
100  NATIVE                           active  

Hint: @vishalbhandari (sort of, indirectly) describes one of the configuration requirements.

Spoiler

Your Core Switch doesn't know about VLAN10.  Defining VLAN10 on that switch, allows ping to work between the two PCs, in the same VLAN, on switches 0 and 1, to work.

Of course, this issue will arise with the other VLANs too, and/or trying to get to a VLAN gateway, not on the same switch as the host.

On Core Switch (for example):

CoreSwitch#conf t
Enter configuration commands, one per line. End with CNTL/Z.
CoreSwitch(config)#vlan 10
CoreSwitch(config-vlan)#end

BTW, VTP could also be used to share VLAN information between switches (also precludes same VLAN, e.g.VLAN 100, known by different names on different switches).