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  • 1.  VLAN & DHCP Problem

    Posted Jan 22, 2010 03:45 PM
    I have a core HP 2910al (J9145A) Switch uplinked to 3 * HP 2520G's (J9299A)

    The Core has 4 vlans:
    Vlan 1 = Management
    Vlan 2 = Data
    Vlan 3 = Voice
    Vlan 4 = Servers

    Core:
    Port 1 = management
    Ports 2 - 20 untagged in Vlan 4
    Ports 21 - 24 tagged in vlans 2 & 3
    IP helper-address is configured for vlan2 (10.0.0.3 Windows DHCP Server)
    DHCP-Relay is on
    IP UDP-BCAST-Forward is on


    Edge switches
    Vlan 1 = Management
    Vlan 2 = Data
    Vlan 3 = Voice

    Ports 1 - 23 untagged vlan 2
    Port 24 tagged in vlan 2

    Problem:
    laptop plugged in a port belonging to Vlan2 does not recieve an IP address via DHCP.
    If I configure a static IP address on the laptop everything if fine, I can even browse shares on the DHCP server and the DHCP server can contact the laptop.
    The switches are running the latest fireware.

    Please help, I need to implement this solution first thing tomorrow!

    Configs:
    CORE

    Running configuration:

    ; J9145A Configuration Editor; Created on release #W.14.38

    hostname "Lornamead Core Switch"
    module 1 type J9145A
    interface 21
    name "Uplink for Edge"
    exit
    interface 22
    name "Uplink for Edge"
    exit
    interface 23
    name "Uplink for Edge"
    exit
    interface 24
    name "Uplink for Edge"
    exit
    ip routing
    ip udp-bcast-forward
    vlan 1
    name "Mgmt"
    untagged 1,21-24
    ip address 172.16.10.254 255.255.255.0
    no untagged 2-20
    exit
    vlan 2
    name "Data"
    ip helper-address 10.0.0.36
    ip address 10.1.0.254 255.255.255.0
    tagged 21-24
    exit
    vlan 3
    name "Voice"
    ip address 192.168.1.254 255.255.255.0
    tagged 21-24
    exit
    vlan 4
    name "Servers"
    untagged 2-20
    ip address 10.0.0.254 255.255.255.0
    exit
    snmp-server community "public" unrestricted
    password manager


    EDGES:


    ; J9299A Configuration Editor; Created on release #J.14.01

    hostname "Lornamead Edge .251"
    ip default-gateway 10.0.0.254
    vlan 1
    name "Mgmt"
    untagged 24
    ip address 172.16.10.251 255.255.255.0
    no untagged 1-23
    exit
    vlan 2
    name "Data"
    untagged 1-23
    tagged 24
    no ip address
    exit
    vlan 3
    name "Voice"
    tagged 24
    no ip address
    exit
    snmp-server community "public" Unrestricted


    Please please can someone helpme??

    Thanks


  • 2.  RE: VLAN & DHCP Problem

    Posted Jan 22, 2010 08:21 PM
    Hi,

    The trouble is that your "core" switch doesn't know how to route the traffic to the DHCP server.
    You can fix it be enabling routing ("ip routing") however this would mean that it would route traffic across all VLANs that it has an IP address on. i.e. your clients would be able to see all your servers etc.


  • 3.  RE: VLAN & DHCP Problem

    Posted Jan 23, 2010 01:17 PM
    Do you have a scope for the 10.1.0.x range set up on your DHCP server?

    Does the laptop get an IP address when plugged into the core switch in either Server Or Data VLAN?




  • 4.  RE: VLAN & DHCP Problem

    Posted Jan 23, 2010 07:58 PM
    I want two questions to you

    1-whic port connect your dhcp server
    2-what is the default gateway address your dhcp server

    and ip routing must have enable on core switch


  • 5.  RE: VLAN & DHCP Problem

    Posted Jan 25, 2010 04:05 AM
    Make sure your DHCP server have the scope and DHCP is reachable when you are using static IP in that specific user VLAN too. Besides, make sure you PC or device connect to the correct VLAN.For your case ip routing is already enabled as I can see "ip routing" in your config. ;p


  • 6.  RE: VLAN & DHCP Problem

    Posted Jan 25, 2010 05:42 AM
    Hah, yes sorry, ignore my comment. I missed that line in the config somehow!
    Try what kianwei suggests :)