11-28-2006 06:42 AM - edited 03-05-2019 01:04 PM
*** the following topology
- router1 with VLAN1: 10.32.214.161/24 and VLAN2: 215.161/24
- interface on this router1 for VLAN2 configured with ip helper-address 10.32.214.163
- router2 with DHCP server for both subnets: only one interface: 10.32.214.163
- PC connected to VLAN2: DHCP client
- sniffer on both the PC and a PC connected to VLAN1
** problem
- When the PC in in VLAN2, it sends out DHCP discover packets - as you should expect it is a normal broadcast
- the sniffer on VLAN1 sees DHCP discover packets coming from 10.32.215.161 going to 10.32.214.163 - also as you should expect
- BUT no answer comes from the DHCP server
- ALSO WEIRD: an 'sh ip d b' on router 2 shows a lease 10.32.215.1 for the MACaddress of the portable!!
** part of the config of router2:
ip subnet-zero
ip dhcp excluded-address 10.32.215.160 10.32.215.255
!
ip dhcp pool EFT-IT2
network 10.32.215.0 255.255.255.0
domain-name univeg.local
default-router 10.32.215.161
netbios-node-type h-node
dns-server 192.168.205.30 4.2.2.1
lease 0 8
!
interface FastEthernet0
ip address 10.32.214.163 255.255.255.0
no ip directed-broadcast
!
ip classless
** part of the config of router1:
interface ATM0
no ip address
no ip redirects
no ip unreachables
no ip proxy-arp
no atm ilmi-keepalive
dsl operating-mode auto
!
interface ATM0.1 point-to-point
no ip redirects
no ip unreachables
no ip proxy-arp
no snmp trap link-status
pvc 8/35
encapsulation aal5mux ppp dialer
dialer pool-member 1
!
!
interface FastEthernet0
description IT-Lan
!
interface FastEthernet1
switchport access vlan 2
!
interface FastEthernet2
shutdown
!
interface FastEthernet3
shutdown
!
interface Vlan1
ip address 10.32.214.161 255.255.255.0
ip nat inside
ip virtual-reassembly
!
interface Vlan2
ip address 10.32.215.161 255.255.255.0
ip helper-address 10.32.214.163
ip nat inside
ip virtual-reassembly
!
interface Dialer0
description toevoegen: 'ip access-group 101 in' (winAmp werkt dan niet - nakijk
en)
ip address negotiated
ip access-group 102 out
no ip redirects
no ip unreachables
no ip proxy-arp
ip nat outside
ip virtual-reassembly
encapsulation ppp
dialer pool 1
dialer-group 1
no cdp enable
ppp authentication chap pap callin
ppp chap hostname xxx
ppp chap password xxx
ppp pap sent-username xxx password xxx
---
Can anyone help me with this?
Thanks!
Solved! Go to Solution.
11-28-2006 06:56 AM
Hi Johan,
i can see "ip dhcp excluded-address 10.32.215.160 10.32.215.255" you have also mentioned the broadcast IP address in the excluded list, so can you make that up 10.32.215.254 & try, it workz fine.
rate this post if cleared.
11-28-2006 07:03 AM
Johan
I am going to make a guess at the problem here. As you describe it the processing of DHCP seems normal, the request is received, an address is assigned, but no response is sent. My guess is that the request came from 10.32.215.161 and that router2 has no route to the 10.32.215 network. That would explain the failure to send the response - if the router does not know where to send the response. Can you post the output of show ip route from router2 which will verify my guess.
HTH
Rick
11-28-2006 06:56 AM
Hi Johan,
i can see "ip dhcp excluded-address 10.32.215.160 10.32.215.255" you have also mentioned the broadcast IP address in the excluded list, so can you make that up 10.32.215.254 & try, it workz fine.
rate this post if cleared.
11-28-2006 07:03 AM
Johan
I am going to make a guess at the problem here. As you describe it the processing of DHCP seems normal, the request is received, an address is assigned, but no response is sent. My guess is that the request came from 10.32.215.161 and that router2 has no route to the 10.32.215 network. That would explain the failure to send the response - if the router does not know where to send the response. Can you post the output of show ip route from router2 which will verify my guess.
HTH
Rick
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