No announcement yet.

Vlan dhcp problem? Option 82?

  • Filter
  • Time
  • Show
Clear All
new posts

  • Vlan dhcp problem? Option 82?

    Here is the catalyst 3560 conf file:

    interface Vlan25
    description Test
    ip address
    ip helper-address

    no ip forward-protocol udp tftp
    no ip forward-protocol udp tacacs


    sw_core#sh ip interface vlan25
    Vlan65 is up, line protocol is up
    Internet address is
    Broadcast address is
    Address determined by non-volatile
    MTU is 1500 bytes
    Helper address is
    Directed broadcast forwarding is disabled
    I have dhcp server on Microsoft win server 2003 ( It works fine for non vlan network. I have created vlan 25, and associate LAN scope to it - 192.168.65.x. My clients are XPs. Dynamics DHCP allocation works fine for laptops, but it does not work for some of my computers. I have tried everything to reset TCP/IP stack etc.... with of no avail.
    Then I have tried to trace dcp server with ethreal:

    When I type the command: ipconfig /renew

    I have on ethreal screen monitoring dhcp server:
    1. DHCO discover

    but when I use xp support command dhcplock and type d (for discover) I have : DHCP discover DHCP offer
    So where is the problem? I do not have slightest idea what to do next!

    Is there some possibility that I have to set server for Option 82?

  • #2
    Re: Vlan dhcp problem? Option 82?

    Strange. So some get an IP, some dont?

    I would think either-
    1. You're out of IP addresses in the scope
    2. You may have to set portfast on some of your access ports- some of the NICs and their machines might not be as quick as others.