Hello
i need your advice, im practicing LAB environment where Router act as DHCP server and using sub interface to Switch 1 and then from Switch 1 To Switch 2 using Dynamic Routing IS-IS where DHCP client under Switch 2. which ip do i need for ip helper-address
here i attached my configuration
thank you
Hi,
Written here two solutions for your "ip helper-address" problem. (Solution 1 and Solution 2)
as a example: if I am you I will not use static routing within a same broadcast domain. I will delete some of unneccessary static routing and use only "Switchport trunking encapsulation dot1q" in CoreSwitch1 interfaces to communicate with both Router1 and Swtch2 (CoreSwitch1-Router1 & CoreSwitch1-Switch2). Here I will describe you how to do it.
Solution 1
Router 1 - Configuration
!
interface GigabitEthernet0/0
no ip address
duplex auto
speed auto
!
interface GigabitEthernet0/0.10
description Users
encapsulation dot1Q 10
ip address 192.168.10.1 255.255.255.0
!
interface GigabitEthernet0/0.11
description P2P_Switch1
encapsulation dot1Q 11
ip address 192.168.11.1 255.255.255.0
!
interface Vlan1
no ip address
shutdown
!
ip classless
!
CoreSwitch1 - Configuration
!
!
interface FastEthernet0/1
description Switch1-DHCP Sever connection
switchport trunk encapsulation dot1q
switchport mode trunk
!
!
!
interface FastEthernet0/10
switchport access vlan 11
switchport mode access
switchport nonegotiate
!
!
interface GigabitEthernet0/1
description Swith1-Switch2 connection
switchport trunk encapsulation dot1q
switchport mode trunk
!
interface GigabitEthernet0/2
description Switch1-Router1 G0/0 sub-interface connection
switchport trunk encapsulation dot1q
switchport mode trunk
!
interface Vlan1
ip address 192.168.1.2 255.255.255.0
!
interface Vlan10
ip address 192.168.10.2 255.255.255.0
ip helper-address 192.168.1.2
ip helper-address 192.168.1.1
!
interface Vlan11
ip address 192.168.11.2 255.255.255.0
ip helper-address 192.168.1.2
ip helper-address 192.168.1.1
!
Show trunk
---------------------------------------------------------------------
CoreSwitch1#sh int trunk
Port Mode Encapsulation Status Native vlan
Fa0/1 on 802.1q trunking 1
Gig0/1 on 802.1q trunking 1
Gig0/2 on 802.1q trunking 1
Port Vlans allowed on trunk
Fa0/1 1-1005
Gig0/1 1-1005
Gig0/2 1-1005
Port Vlans allowed and active in management domain
Fa0/1 1,10,11
Gig0/1 1,10,11
Gig0/2 1,10,11
Port Vlans in spanning tree forwarding state and not pruned
Fa0/1 1,10,11
Gig0/1 1,10,11
Gig0/2 1,10,11
CoreSwitch1#
Switch2 - Configuration
!
interface FastEthernet0/1
switchport access vlan 10
switchport mode access
switchport nonegotiate
!
interface FastEthernet0/2
switchport access vlan 10
switchport mode access
switchport nonegotiate
!
interface FastEthernet0/3
switchport access vlan 10
switchport mode access
switchport nonegotiate
!
interface FastEthernet0/4
switchport access vlan 10
switchport mode access
switchport nonegotiate
!
!
interface GigabitEthernet0/1
!
interface GigabitEthernet0/2
!
interface Vlan1
no ip address
shutdown
!
-------------------------------------------------------------------------------
Switch2#sh int trunk
Port Mode Encapsulation Status Native vlan
Gig0/1 auto n-802.1q trunking 1
Port Vlans allowed on trunk
Gig0/1 1-1005
Port Vlans allowed and active in management domain
Gig0/1 1,10
Port Vlans in spanning tree forwarding state and not pruned
Gig0/1 1,10
Switch2#
DHCP-Server - configurations
Solution 2
In this solution DHCP pool exist in the Router1
You dont need to have addtional DHCP Server but Switches configuration exist same as above. You can remove "ip helper-address 192.168.1.1" from CoreSwitch1.
!
no ip helper-address 192.168.1.1
!
You have to add additional comands as below to Router1 as below, previous configurations remain as same.
!
!
ip dhcp excluded-address 192.168.10.1 192.168.10.3
ip dhcp excluded-address 192.168.11.1 192.168.11.3
!
!
ip dhcp pool user
network 192.168.10.0 255.255.255.0
default-router 192.168.10.1
!
ip dhcp pool CoreSwitch1
network 192.168.11.0 255.255.255.0
default-router 192.168.11.1
!
!
