Warning message

  • Cisco Support Forums is in Read Only mode while the site is being migrated.
  • Cisco Support Forums is in Read Only mode while the site is being migrated.

Vlan forwarding DHCP request to Windows server

Answered Question
May 8th, 2014
User Badges:

I'm new to Switches. I inherited 2 switches 3550 and 3560. My core switch is 3560 linked to 3550 on port 1. One of the vlan24  with IP is not pointing request to my windows 2008 DHCP server for IP leases. I have a IP-Helper associated with the vlan24. I need all your help

core#sh running-config
Building configuration...

interface Vlan24
 ip address
 ip helper-address
 ip helper-address


also a show vlan has:

VLAN Name                             Status    Ports
---- -------------------------------- --------- -------------------------------
1    default                          active    Gi0/1, Gi0/2, Gi0/3, Gi0/4
2    VLAN0002                         active    Fa0/2
3    VLAN0003                         active    Fa0/3, Fa0/4, Fa0/5, Fa0/6
                                                Fa0/7, Fa0/8, Fa0/9, Fa0/10
                                                Fa0/11, Fa0/12, Fa0/13, Fa0/14
                                                Fa0/15, Fa0/16, Fa0/17, Fa0/18
                                                Fa0/19, Fa0/20, Fa0/21, Fa0/22
                                                Fa0/23, Fa0/24, Fa0/25, Fa0/26
                                                Fa0/27, Fa0/28, Fa0/29, Fa0/30
                                                Fa0/31, Fa0/32, Fa0/33, Fa0/34
                                                Fa0/35, Fa0/36, Fa0/37, Fa0/38
                                                Fa0/39, Fa0/40, Fa0/41, Fa0/42
                                                Fa0/43, Fa0/44, Fa0/45, Fa0/46
                                                Fa0/47, Fa0/48
4    QCert_Vlan                       active
24   Wireless_10.164.24               active



Correct Answer by cadet alain about 3 years 3 months ago

Can you ping the DHCP server sourcing from Vlan24 on the switch ?





  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 5 (1 ratings)
osagiefe1 Thu, 05/08/2014 - 11:14
User Badges:

I would say yes because prior to me they used this vlan in conjuction with a scope in DHCP for all wireless devices. The scope still remains however, I've since replace the centrally managed WAP (Wireless Access Point) with AP541N

osagiefe1 Thu, 05/08/2014 - 11:55
User Badges:

I will be honest I don't know how to Tag vlan 24 on the AP except by giving it the vlan # as shown:

cadet alain Thu, 05/08/2014 - 11:43
User Badges:
  • Purple, 4500 points or more


Is the DHCP service enabled on the switch acting as a relay agent?

To verify, output of sh run | i service dhcp should not be empty.

If it is not enabled, do it with global config command "service dhcp"





osagiefe1 Thu, 05/08/2014 - 12:03
User Badges:

core#sh ip dhcp ?
  binding   DHCP address bindings
  conflict  DHCP address conflicts
  database  DHCP database agents
  import    Show Imported Parameters
  relay     Miscellaneous DHCP relay information
  server    Miscellaneous DHCP server information
  snooping  DHCP snooping

gaatl-core#sh ip dhcp server
% Incomplete command.

gaatl-core#sh ip dhcp server ?
  statistics  DHCP server statistics

gaatl-core#sh ip dhcp server stat
gaatl-core#sh ip dhcp server statistics
Memory usage         4285
Address pools        0
Database agents      0
Automatic bindings   0
Manual bindings      0
Expired bindings     0
Malformed messages   7

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

Message              Sent
BOOTREPLY            0
DHCPOFFER            0
DHCPACK              0
DHCPNAK              0


Correct Answer
cadet alain Thu, 05/08/2014 - 12:20
User Badges:
  • Purple, 4500 points or more

Can you ping the DHCP server sourcing from Vlan24 on the switch ?





osagiefe1 Thu, 05/08/2014 - 12:46
User Badges:

Yes I can ping the DHCP server from the switch. However when I do a traceroute to it, I get an endless loop



This Discussion