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6637 Views 4 Replies Latest reply: Jul 1, 2010 12:31 PM by mfarrenkopf RSS

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Vlan Problems

Jul 1, 2010 9:47 AM

ndikumvitalis 2 posts since
Jun 9, 2010

Just configure a vlan on a cisco 2900 switch.

Unfortunately I cannot ping any device on the same vlan. Is there anything else I need to do?

Can someone help please

 

 

  • mfarrenkopf 5 posts since
    Aug 18, 2008
    Currently Being Moderated
    1. Jul 1, 2010 10:30 AM (in response to ndikumvitalis)
    Re: Vlan Problems

    Your question sounds like you're only using one switch right now, so I'm not including possible ideas about problems with uplinks between switches.

     

    Issues to look at:

     

    • Are you sure the VLAN is created?  Do a show vlan brief and make sure it shows up there.
    • Is the VLAN suspended?  show vlan brief should say the VLAN is active, not suspended.
    • Are you getting physical link on the ports?  Make sure the ports are not in a shutdown state.
    • Are you sure the physical ports are on the same VLAN?  Check the switchport access vlan commands.
    • Are you running into trunk negotiation or spanning-tree delays?  Configure them with switchport mode access and spanning-tree portfast commands.
    • Are the devices all on the same subnet?  Check their IP addresses and netmasks to make sure.
    • Are the devices configured to respond to ping?  Windows XP SP3 turns off ping responses by default.  Other operating systems may do the same.
    • Are you seeing MAC addresses on the ports?  Do a show mac-address-table int fa0/n (where n is the port number) to see (some IOSs are now show mac address-table (no hyphen between "mac" and "address-table")).

     

    Without seeing a configuration, these are the items I can think of right off.

  • mfarrenkopf 5 posts since
    Aug 18, 2008
    Currently Being Moderated
    3. Jul 1, 2010 12:31 PM (in response to ndikumvitalis)
    Re: Vlan Problems

    A suspended VLAN won't pass traffic.  Example:

     

    Switch#show vlan brief

    VLAN Name                             Status    Ports
    ---- -------------------------------- --------- -------------------------------

    1    default                          active    Gi0/1
    10   Production-Data                  active    Fa0/1, Fa0/2, Fa0/3
    999  Unused-Ports                     suspended

     

    In this example, any ports assigned to VLAN 999 (switchport access vlan 999) won't pass traffic at all, even between each other.  We use this as a security feature so that even if an unused port is accidentally left unshut, any connected devices still can't pass traffic between each other.  A VLAN being suspended is not the default, so if you didn't configure it like that then that shouldn't be a problem.  But it's something to check.

     

    Are these PCs running Windows XP?  My next thought is that they're running XP SP3 and not allowing ping responses.  If you haven't given your switch its own IP address, try configuring your switch with a switch virtual interface (SVI) in VLAN 10 to give it an IP address and see if you can ping the switch from a PC:

     

    interface Vlan10

    ip address 10.1.1.93 255.255.255.0

    no shutdown

     

    I just pulled 10.1.1.93 out of thin air; make sure the IP address you assign is available.  Also, change your netmask to match what the PCs have as a netmask.  If you can ping the switch's IP address, then communication is occurring on the VLAN.

  • Conwyn 7,914 posts since
    Sep 10, 2008
    Currently Being Moderated
    4. Jul 1, 2010 12:50 PM (in response to ndikumvitalis)
    Re: Vlan Problems

    Hi N

     

    Switch off your firewall on your PC

     

    Regards Conwyn

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