Help: 2621 DHCP server problem

Discussion in 'Cisco' started by Weiguang Shi, Oct 16, 2003.

  1. Weiguang Shi

    Weiguang Shi Guest

    Hello,

    I've set up a 2621 router as a DHCP server and connected to its fa0/0 port a
    3524 switch which was not configured before--I was trying to do autoinstall,
    you see.

    Subnet: 192.168.128

    +------+ .3 +------------+
    | 3524 |-----------------| 2621 DHCPD |------------- serial link
    +------+ fa0/0 +------------+


    The 2621 has been receiving DHCPDISCOVER all the time, but just hasn't
    answered at all. Here is the output of "show ip dhcp server statistics":

    Memory usage 14338
    Address pools 1
    Database agents 0
    Automatic bindings 0
    Manual bindings 0
    Expired bindings 0
    Malformed messages 0
    Secure arp entries 0

    Message Received
    BOOTREQUEST 0
    DHCPDISCOVER 159
    DHCPREQUEST 0
    DHCPDECLINE 0
    DHCPRELEASE 0
    DHCPINFORM 0

    Message Sent
    BOOTREPLY 0
    DHCPOFFER 0
    DHCPACK 0
    DHCPNAK 0


    My DHCP configuration on the 2621 is:

    no ip dhcp conflict logging
    ip dhcp excluded-address 192.168.128.3
    !
    ip dhcp pool 1
    network 192.168.128.64 255.255.255.192
    next-server 192.168.131.1
    default-router 192.168.128.3
    domain-name inetlab.ualberta.ca
    dns-server 192.168.131.1

    BTW, previously, I connected the 3524 to a Linux PC where I ran a DHCP server
    and it worked perfectly--this is one of the reasons that I think something's
    wrong at the 2621 side.

    Thanks very much,
    Weiguang
     
    Weiguang Shi, Oct 16, 2003
    #1
    1. Advertising

  2. On Thu, 16 Oct 2003 18:12:35 +0000, Weiguang Shi wrote:

    > Hello,
    >
    > I've set up a 2621 router as a DHCP server and connected to its fa0/0 port
    > a 3524 switch which was not configured before--I was trying to do
    > autoinstall, you see.


    Show runn interface fa0/0?
    Debug ip dhcp server packet?

    --
    Rgds,
    Martin
     
    Martin Gallagher, Oct 17, 2003
    #2
    1. Advertising

  3. Weiguang Shi

    Weiguang Shi Guest

    In article <>, Martin Gallagher wrote:
    > Show runn interface fa0/0?
    > Debug ip dhcp server packet?


    I am sure it was not the fa0/0, and the debug gave me (repeatedly)
    Oct 16 02:52:20.940: DHCPD: DHCPDISCOVER received from client 0063.6973
    .636f.2d30.3030.372e.6562.3934.2e37.3363.302d.564c.31 on interface
    FastEthernet0/0.

    Another debug command "debug ip dhcp server event" gave me
    Oct 16 03:00:27.116: DHCPD: there is no address pool for 192.168.128.3

    BTW, when I used the "ip helper-address" at fa0/0 and directed the DHCP
    requests to a DHCP server on a Linux box 3 hops away, it worked fine.

    Thanks,
    Wei
     
    Weiguang Shi, Oct 17, 2003
    #3
  4. Hi,
    it looks to me as if your Fa0/0 and the dhcp-pool are not on the same
    subnet...
    in the dhc-pool you define the subnet as 192.168.128.64/28.
    The fa0/0 is on 192.168.128.3 (unknown mask).
    So it might be that the dhcp-server receives the discover but recons
    that is is not on a scope defined in one of it's pools and silently
    rejects the packet.
    Try to change either the IT-address of the fa0/0 to fit into the pool or
    change the pool's network-command

    Mathias

    Weiguang Shi schrieb:
    > Hello,
    >
    > I've set up a 2621 router as a DHCP server and connected to its fa0/0 port a
    > 3524 switch which was not configured before--I was trying to do autoinstall,
    > you see.
    >
    > Subnet: 192.168.128
    >
    > +------+ .3 +------------+
    > | 3524 |-----------------| 2621 DHCPD |------------- serial link
    > +------+ fa0/0 +------------+
    >
    >


    > My DHCP configuration on the 2621 is:
    >
    > no ip dhcp conflict logging
    > ip dhcp excluded-address 192.168.128.3
    > !
    > ip dhcp pool 1
    > network 192.168.128.64 255.255.255.192
    > next-server 192.168.131.1
    > default-router 192.168.128.3
    > domain-name inetlab.ualberta.ca
    > dns-server 192.168.131.1
    >
    > BTW, previously, I connected the 3524 to a Linux PC where I ran a DHCP server
    > and it worked perfectly--this is one of the reasons that I think something's
    > wrong at the 2621 side.
    >
    > Thanks very much,
    > Weiguang



    --
    CCIE #11220
    Everything written is MY opinion only, not the one of my company or
    employer unless otherwise noted

    The early bird gets the worm, but the second mouse gets the cheese
     
    Mathias Gaertner, Oct 18, 2003
    #4
  5. On Fri, 17 Oct 2003 15:46:06 +0000, Weiguang Shi wrote:

    >
    > I am sure it was not the fa0/0, and the debug gave me (repeatedly)
    > Oct 16 02:52:20.940: DHCPD: DHCPDISCOVER received from client 0063.6973
    > .636f.2d30.3030.372e.6562.3934.2e37.3363.302d.564c.31 on interface
    > FastEthernet0/0.


    You may be sure that it was not fa0/0, but I'm not. See Mathias post for
    the explaination.

    >
    > Another debug command "debug ip dhcp server event" gave me
    > Oct 16 03:00:27.116: DHCPD: there is no address pool for 192.168.128.3


    This fits.

    > BTW, when I used the "ip helper-address" at fa0/0 and directed the DHCP
    > requests to a DHCP server on a Linux box 3 hops away, it worked fine.


    When you use the Linux DHCP server, it only has the giaddr, 192.168.128.3,
    to go on, so using a different mask for the pool will work.

    --
    Rgds,
    Martin
     
    Martin Gallagher, Oct 18, 2003
    #5
  6. Weiguang Shi

    Weiguang Shi Guest

    Thanks very much. It worked.

    Wei
     
    Weiguang Shi, Oct 20, 2003
    #6
  7. Weiguang Shi

    Weiguang Shi Guest

    Thanks very much.

    It's working now.

    Wei
     
    Weiguang Shi, Oct 20, 2003
    #7
  8. Weiguang Shi

    Weiguang Shi Guest

    One more question, though.

    The Ethernet address of the switch is "00:07:eb:94:73:c0" and I wanted to
    assign a manual IP address 192.168.128.64 to it. So I declared:

    no ip dhcp conflict logging
    ip dhcp excluded-address 192.168.128.3

    ip dhcp pool 1
    network 192.168.128.0 255.255.255.0
    default-router 192.168.128.3
    dns-server 192.168.131.1
    next-server 192.168.131.201

    ip dhcp pool primus3
    host 192.168.128.64
    hardware-address 0007.eb94.73c0
    client-name primus3
    default-router 192.168.128.3
    dns-server 192.168.131.1
    next-server 192.168.131.1

    Afterwards, as I did a "show ip dhcp binding" on the router, I get the
    following results:

    Router#show ip dhcp binding
    Bindings from all pools not associated with VRF:
    IP address Client-ID/ Lease expiration Type
    Hardware address/
    User name
    192.168.128.1 0063.6973.636f.2d30. Mar 01 1993 05:02 PM Automatic
    3030.372e.6562.3934.
    2e37.3363.302d.564c.
    31
    192.168.128.2 0100.0750.d550.c3 Mar 01 1993 05:02 PM Automatic
    192.168.128.4 0100.0750.786c.82 Mar 01 1993 05:04 PM Automatic
    192.168.128.64 0007.eb94.73c0 Infinite Manual


    So the switch is assigned the address 192.168.128.1 instead of 192.168.128.64.
    And its Client-ID/Hardware address/User name is a much longer string than a
    48-bit Ethernet address! I tried to use this string in a hardware-address
    statement when declaring a manual-binding pool, but the router complained:

    % DHCP could not parse the hardware address. Check character 39 (.).

    Could you explain what went wrong?

    Thanks again.
    Wei
     
    Weiguang Shi, Oct 20, 2003
    #8
  9. On Mon, 20 Oct 2003 17:01:45 +0000, Weiguang Shi wrote:

    > One more question, though.


    > Router#show ip dhcp binding
    > Bindings from all pools not associated with VRF: IP address
    > Client-ID/ Lease expiration Type
    > Hardware address/
    > User name
    > 192.168.128.1 0063.6973.636f.2d30. Mar 01 1993 05:02 PM
    > Automatic
    > 3030.372e.6562.3934.
    > 2e37.3363.302d.564c.
    > 31
    > 192.168.128.2 0100.0750.d550.c3 Mar 01 1993 05:02 PM
    > Automatic 192.168.128.4 0100.0750.786c.82 Mar 01 1993 05:04
    > PM Automatic 192.168.128.64 0007.eb94.73c0 Infinite
    > Manual
    >
    >
    > So the switch is assigned the address 192.168.128.1 instead of
    > 192.168.128.64. And its Client-ID/Hardware address/User name is a much
    > longer string than a 48-bit Ethernet address! I tried to use this string
    > in a hardware-address statement when declaring a manual-binding pool, but
    > the router complained:


    That identifier is a client-id. There is a client-id command in the
    dhcp pool config, so add that to the primus3 pool. The dhcp server will
    use the client-id, if present, in preference to the MAC address.
     
    Martin Gallagher, Oct 21, 2003
    #9
  10. Weiguang Shi

    Weiguang Shi Guest

    In article <>, Martin Gallagher wrote:
    > That identifier is a client-id. There is a client-id command in the
    >dhcp pool config, so add that to the primus3 pool. The dhcp server will
    >use the client-id, if present, in preference to the MAC address.


    Given that every device on a LAN has a MAC address, a client-id seems redundant
    to me.

    Anyway, THANKS A LOT!

    Wei
     
    Weiguang Shi, Oct 21, 2003
    #10
  11. ~ > That identifier is a client-id. There is a client-id command in the
    ~ >dhcp pool config, so add that to the primus3 pool. The dhcp server will
    ~ >use the client-id, if present, in preference to the MAC address.
    ~
    ~ Given that every device on a LAN has a MAC address, a client-id seems redundant
    ~ to me.

    But not ALL clients have MAC addresses - for example, PPP clients
    don't. (Bear in mind that DHCP was designed to work on all media.)

    Aaron
     
    Aaron Leonard, Oct 27, 2003
    #11
    1. Advertising

Want to reply to this thread or ask your own question?

It takes just 2 minutes to sign up (and it's free!). Just click the sign up button to choose a username and then you can ask your own questions on the forum.
Similar Threads
  1. Alexis Crawford
    Replies:
    1
    Views:
    3,997
    Walter Roberson
    Apr 2, 2004
  2. Andrew Albert
    Replies:
    3
    Views:
    3,625
    Barry Margolin
    Jul 21, 2004
  3. J
    Replies:
    3
    Views:
    3,530
  4. sonicgravy
    Replies:
    0
    Views:
    1,480
    sonicgravy
    Nov 13, 2006
  5. =?Utf-8?B?SGFyb29uIE1hbGlr?=

    DHCP Server migration to a 64 bit Clustered Server

    =?Utf-8?B?SGFyb29uIE1hbGlr?=, May 30, 2007, in forum: Windows 64bit
    Replies:
    2
    Views:
    751
    =?Utf-8?B?SGFyb29uIE1hbGlr?=
    Jun 4, 2007
Loading...

Share This Page