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Issues with DHCP forward (ip helper-address)

housing21
Level 1
Level 1

Hi,

I am having some issues with BOOTP/DHCP forward on a Cisco 1751 router (IOS (tm) C1700 Software (C1700-K8SY7-M), Version 12.2(4)T3, RELEASE SOFTWARE (fc3)).

I have set-up an ip helper-address on the LAN interface as there is no DHCP server at this site and as we want to keep DHCP centrally managed.

It is working for nearly everything but Windows XP clients, which reject the IP address.

The DHCP server is running Windows NT 4.0 (I have tried with a Windows 2003 server and the issue remains the same).

Below is the router config.

Has someone experienced a similar issue ?

Can you help ?

Many thanks,

Christophe.

=====================================================

Config:

------

! Last configuration change at 17:39:30 bst Mon Sep 27 2004

! NVRAM config last updated at 15:23:10 bst Mon Sep 27 2004

!

version 12.2

no service pad

service timestamps debug datetime localtime

service timestamps log datetime localtime

service password-encryption

!

hostname LONWEST-R-RLI01

!

boot system flash

logging buffered 4096 debugging

enable password 7 xxxxxxxxxx

!

username AAA password 7 xxxxxxxxx

memory-size iomem 20

clock timezone gmt 0

clock summer-time bst recurring

ip subnet-zero

!

!

ip ftp username router

ip ftp password 7 xxxxxxxxxx

ip domain-list housing21.co.uk

ip domain-name housing21.co.uk

ip name-server 10.1.1.11

ip name-server 10.1.10.18

!

ip ssh time-out 120

ip ssh authentication-retries 3

isdn switch-type basic-net3

!

crypto mib ipsec flowmib history tunnel size 200

crypto mib ipsec flowmib history failure size 200

!

!

!

interface FastEthernet0/0

ip address 10.10.1.1 255.255.0.0

ip broadcast-address 10.10.0.0

ip helper-address 10.1.10.1

speed auto

!

interface Serial0/0

description BEACONS Leased Line (NXGB2xxxxxx)

bandwidth 256

backup delay 0 300

backup interface Dialer1

ip unnumbered FastEthernet0/0

ip broadcast-address 0.0.0.0

priority-group 1

!

interface BRI1/0

no ip address

ip broadcast-address 0.0.0.0

encapsulation ppp

dialer pool-member 1

isdn switch-type basic-net3

ppp authentication chap

ppp multilink

!

interface Dialer1

description BEACONS ISDN Backup

ip unnumbered FastEthernet0/0

ip broadcast-address 0.0.0.0

encapsulation ppp

load-interval 30

dialer pool 1

dialer remote-name AAA

dialer string 01xxxxxxxxx

dialer load-threshold 150 either

dialer-group 1

priority-group 1

no cdp enable

ppp authentication chap

ppp multilink

!

router eigrp 1

network 10.10.0.0 0.0.255.255

auto-summary

no eigrp log-neighbor-changes

!

ip classless

ip forward-protocol udp 135

no ip http server

ip pim bidir-enable

!

priority-list 1 protocol ip high tcp 1494

priority-list 1 protocol ip high udp 1494

priority-list 1 protocol ip high tcp 1604

priority-list 1 protocol ip high udp 1604

priority-list 1 protocol ip normal

dialer-list 1 protocol ip permit

!

snmp-server community xxxxxx RO

snmp-server community xxxxxx RW

snmp-server location Housing 21 - LONWEST - 1st Floor - Back-Office (Systems and Finance Manager)

snmp-server contact Housing 21 Network Team

banner motd ^CLONWEST-R-RLI01^C

!

line con 0

session-timeout 3600

stopbits 1

line aux 0

password 7 xxxxxxxxxxxxxxxxxxxx

login

line vty 0 4

session-timeout 3600

password 7 xxxxxxxxxxxxxxxxxxxx

login

!

sntp server 10.1.10.18

end

3 Replies 3

Hello Christophe,

I might be totally off here, but I remember coming across this problem before, the issue is not with the router or the DHCP server, but with the client configuration. You need to enable NetBIOS over TCP on your XP client, here is how:

Click Start, click Control Panel, click Network and Internet Connections, and then click Network Connections.

Right-click the network connection that you want to configure, and then click Properties.

On the General tab (for a local area connection) or on the Networking tab (for all other connections), click Internet Protocol (TCP/IP), and then click Properties.

Click Advanced, click the WINS tab, and then click Enable NetBIOS over TCP/IP.

Note If the DHCP server provides the NetBIOS settings, you can click Default: Use NetBIOS setting from the DHCP server. If static IP address is used or the DHCP server does not provide NetBIOS setting, enable NetBIOS over TCP/IP.

Click OK two times, and then click Close.

Let me know if this makes a difference...

Regards,

Georg

www.solutionfinders.nl

Hi Georg,

Many thanks for your reply.

I will try this and let you know if it solve the issue.

Regards,

Christophe.

Hi Georg,

Many thanks for your help.

We have tried to enable NetBIOS over TCP/IP, but it does make any difference.

XP clients are still not accepting the DHCP settings forwarded by the router.

I have added the following command in the config and this seems to solve the issue:

ip dhcp limited-broadcast-address

Best regards,

Christophe