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Wireless Networks Thread, Vlans in Technical; HI Im setting up a new classroom and i want to put them on a separate Vlan. The Problem: i ...
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    Sunderwood's Avatar
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    Vlans

    HI

    Im setting up a new classroom and i want to put them on a separate Vlan.

    The Problem:

    i have set the interface vlan up on the router and i know all this works fine because i have setup a port on that vlan and i get the correct address from the dhcp server...

    i then go to a switch which is 2 hops away, all the vlans are created correctly on the switches on route and all the links which are from the router are setup as trunks and allow all vlans.

    I connect a PC and the switch can't get a dhcp address? i set the port back to the default vlan and it gets an ip and works fine (so connectivity is ok)

    All the encapsulation is set to dot1q?

    any ideas?

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    EduTech's Avatar
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    Set up a static ip address and try and ping the switch from that machine.

    If that works, try and ping the router interface.. that is set up for that Vlan

    Regards

    James.

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    Sunderwood's Avatar
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    OK update!!

    I took my a new switch (erased Startup) and went down to the main router and bypassed to the switch in the middle.

    i then connected all the cables and configs the same as they are upstairs and all seems to be working fine?

    its until i go to the switch upstairs thats 2 hops away that i can not get an ip..

    All links are set as trunks!!!

    What could be the issue?

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    Quote Originally Posted by Sunderwood View Post
    OK update!!

    I took my a new switch (erased Startup) and went down to the main router and bypassed to the switch in the middle.

    i then connected all the cables and configs the same as they are upstairs and all seems to be working fine?

    its until i go to the switch upstairs thats 2 hops away that i can not get an ip..

    All links are set as trunks!!!

    What could be the issue?
    Check to if:

    - The encapsulation is correct on all the trunk links
    - there are allowed vlans list on the trunks all from the router to the switch that is having issues
    - is the dhcp server on another vlan, if so enable the ip helper command in the the router.

    Ash.

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    Sunderwood's Avatar
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    Hi thanks for the reply.


    yer i have that all setup as follows:

    My interface on the router:

    interface Vlan4
    description Technology Suite
    ip address 192.168.10.1 255.255.255.0
    ip helper-address 172.28.47.29
    ip helper-address 172.28.47.30


    The status of the switchport on all the trunks:

    Name: Gi1/0/52
    Switchport: Enabled
    Administrative Mode: trunk
    Operational Mode: trunk
    Administrative Trunking Encapsulation: dot1q
    Operational Trunking Encapsulation: dot1q
    Negotiation of Trunking: On
    Access Mode VLAN: 1 (default)
    Trunking Native Mode VLAN: 1 (default)
    Administrative Native VLAN tagging: enabled
    Voice VLAN: none
    Administrative private-vlan host-association: none
    Administrative private-vlan mapping: none
    Administrative private-vlan trunk native VLAN: none
    Administrative private-vlan trunk Native VLAN tagging: enable
    d
    Administrative private-vlan trunk encapsulation: dot1q
    Administrative private-vlan trunk normal VLANs: none
    Administrative private-vlan trunk private VLANs: none
    Operational private-vlan: none
    Trunking VLANs Enabled: ALL
    Pruning VLANs Enabled: 2-1001
    Capture Mode Disabled
    Capture VLANs Allowed: ALL

    Protected: false
    Unknown unicast blocked: disabled
    Unknown multicast blocked: disabled
    Appliance trust: none


    i have checked all links and they are setup like this?

    What else could be wrong?

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    Sunderwood's Avatar
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    OK i think i have narrowed it down to the switches 2950's

    i have done the same configuration on a 2960 and i get an ip straight away. i can also ping the default gateway from every switch except the one i am trying to get working?

    Could it be a firmware upgrade?

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    Does the switch that sits between the router and the switch that has the P.C on it have the VLAN that you want the P.C to be a member of

    PC--SWITCH(VLAN 3)-----SWITCH(VLAN3)-----ROUTER(VLAN3)

    The transit switch must host the VLAN that it you want to carry, even if there are no members of that vlan on that switch

    Make sure that the links on the HP that are being used as trunks are all members of the tagged vlan.

    Hope this helps



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