router not reachable over a trunk link

Discussion in 'Cisco' started by blu_aqua, Apr 5, 2005.

  1. blu_aqua

    blu_aqua Guest

    Hi there,
    I have this situation:

    my pc is connected to a port of a C2950G-EI switch that is assigned to
    VLan77

    the above C2950G switch is connected to a C3508 switch. I configured both
    ports involved in this connection as trunk link 802.1q.

    the C3508 switch is connected to a C2950T switch. I configured both ports
    involved in this connection as trunk link 802.1q.

    a 1721 router is connected to a port of the above C2950T switch. That port
    is configured as trunk link 802.1q.

    I can't ping the router from my pc. Why?
    Trunk links aren't supposed to let me ping the router easily?
    Do I have to configure something on the router also? But I can't see
    anything regarding vlans and things like that, on the ethernet interface of
    the router.

    Where is my mistake?

    Thanks in advance.

    blu_aqua

    P.s.: here is a wonderful :) example of ascii art that "should" help you
    get a quick glance on my situation. The "t" simbolizes a trunk link.

    [MyPC]-vlan77>[C2950G]<tttttttt>[C3508]<tttttttt>[C2950T]<tttttttt>[router1721]
     
    blu_aqua, Apr 5, 2005
    #1
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  2. blu_aqua

    cc Guest

    ok.. let me elabroate your topology:

    /[2950G]<==>[3508]<==>[2950T]
    pc/ ^
    |
    [1721]

    Problem:
    Your pc cannot ping the router?

    //////////
    Ok, let to clarify a few things here

    How many Vlans do you have?
    Can your pc ping its default gateway?
    Can your router ping the other switches?
    Can your pc ping the other switches?
    Did you create some sort of sub-interface on the router?

    Cheers,
    CC
     
    cc, Apr 5, 2005
    #2
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  3. blu_aqua

    blu_aqua Guest

    Thanks for your answer! :)
    It's not clear from your ascii art (nor from mine).
    Let me state it: the router is connected to the 2950T
    [2950G]<==>[3508]<==>[2950T]
    pc/ ^
    |
    [1721]

    About your questions:

    > How many Vlans do you have?


    I have 6 vlans.

    > Can your pc ping its default gateway?


    pc default gateway is supposed to be the router itself. Can I do that? Or am
    I wrong?
    If I'm wrong: who should be the default gateway? the ip address of the
    vlan?
    Do I need a different gateway for each vlan?
    Please give some IOS command examples :)

    > Can your router ping the other switches?


    Yes

    > Can your pc ping the other switches?


    No because the other switches are on VLAN1 (management vlan). But my pc can
    ping other pc in VLAN77 (77 is the vlan of my pc)

    > Did you create some sort of sub-interface on the router?


    No. Should I?
    I currently have ATM0, ATM0.1, Fastethernet0.
    Consider that I'm going to put a pix 506e between the router and the
    LAN....so maybe I should create some sub-interface on that.
    If possible please provide some IOS command examples.


    "cc" <> ha scritto nel messaggio
    news:...
    > ok.. let me elabroate your topology:
    >
    > /[2950G]<==>[3508]<==>[2950T]
    > pc/ ^
    > |
    > [1721]
    >
    > Problem:
    > Your pc cannot ping the router?
    >
    > //////////
    > Ok, let to clarify a few things here
    >
    > How many Vlans do you have?
    > Can your pc ping its default gateway?
    > Can your router ping the other switches?
    > Can your pc ping the other switches?
    > Did you create some sort of sub-interface on the router?
    >
    > Cheers,
    > CC
    >
     
    blu_aqua, Apr 5, 2005
    #3
  4. blu_aqua

    DB Guest

    To troubleshoot Trunking you need to check on a few things :
    Make sure the Layer2 int mode configured on both ends of the link are
    valid.
    Should be either trunk,dynamic or nonegotiate.
    Is the native vlan the same on both ends of the trunk?

    Is the mask/address range the same on PC and router?

    Cheers,
    DB
     
    DB, Apr 5, 2005
    #4
  5. blu_aqua

    blu_aqua Guest

    "DB" <> ha scritto nel messaggio
    news:...
    > To troubleshoot Trunking you need to check on a few things :
    > Make sure the Layer2 int mode configured on both ends of the link are
    > valid.
    > Should be either trunk,dynamic or nonegotiate.


    It's "trunk" on both sides

    > Is the native vlan the same on both ends of the trunk?


    yes (why does this matter?)

    >
    > Is the mask/address range the same on PC and router?


    yes

    >
    > Cheers,
    > DB
    >
     
    blu_aqua, Apr 6, 2005
    #5
  6. blu_aqua

    DB Guest

    Native VLAN should be the same otherwise spanning-tree loops might
    occur.
    Speaking of STP, did you check the STP on the switches.Are they the
    same?
     
    DB, Apr 6, 2005
    #6
  7. U¿ytkownik "blu_aqua" <> napisa³ w
    wiadomo¶ci news:4yu4e.38760$...
    >> Did you create some sort of sub-interface on the router?

    >
    > No. Should I?


    Yes, you should create subinterface for each VLAN, that you want to
    comunicate with router (or between VLAN). For each subinterface you must
    configure encapsulation and vlan-number identifies the VLAN for which the
    subinterface will carry traffic.

    cheers,

    Kamil Olszewski
     
    Kamil Olszewski, Apr 9, 2005
    #7
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