Cisco 1841 using the 2 built in fe ports with dhcp

[randy kruen]

Hi. This is a great forum, you guys have helped me alot here. I am running a Cisco 1841 with a wic 1dsu t1 card facing the outside world, and a hwic 4esw card facing me. I am trying to configure and use the 2 built in fe ports so I am not relying on the hwic 4esw card. Both fe0/0 and 0/1 are good to the outside world, but I have only been able to add dhcp to fe0/0, if I use fe0/1 I need to use a static ip address. How can I add another vlan pool to fe0/1? Both of these ports seem to default to the vlan1 pool, I cannot seem to change that. Config below, and thanks in advance for your help!

no ip dhcp use vrf connected
!
ip dhcp pool vlan1
network 192.168.4.0 255.255.255.0
default-router 192.168.3.1
dns-server 24.153.23.66 24.153.22.67
!
ip dhcp pool vlan2
network 192.168.3.0 255.255.255.0
default-router 192.168.3.1
dns-server 24.153.23.66 24.153.22.67
!
ip cef
no ipv6 cef
!
multilink bundle-name authenticated
!
crypto pki token default removal timeout 0
!
license udi pid CISCO1841 sn FTX13348050
archive
log config
hidekeys
!
redundancy
!
interface FastEthernet0/0
ip address 192.168.4.1 255.255.255.0
ip helper-address 192.168.2.2
speed 100
full-duplex
!
interface FastEthernet0/1
ip address 192.168.5.1 255.255.255.0
ip helper-address 192.168.2.2
speed 100
full-duplex
!
interface Serial0/0/0
ip address 192.168.2.1 255.255.255.0
service-module t1 timeslots 1-24
service-module t1 fdl ansi
!
interface FastEthernet0/1/0
switchport access vlan 2
no ip address
duplex full
speed 100
!
interface FastEthernet0/1/1
switchport access vlan 2
no ip address
duplex full
speed 100
!
interface FastEthernet0/1/2
switchport access vlan 2
no ip address
duplex full
speed 100
!
interface FastEthernet0/1/3
switchport access vlan 2
no ip address
duplex full
speed 100
!
interface Vlan1
no ip address
!
interface Vlan2
ip address 192.168.3.1 255.255.255.0
ip helper-address 192.168.2.2
vlan-id dot1q 2
exit-vlan-config
!
ip forward-protocol nd
no ip http server
no ip http secure-server
!
ip route 0.0.0.0 0.0.0.0 192.168.2.2
!
control-plane

[Jon Marshall]

Not sure what you are trying to do here.

You have two DHCP pools both using 192.168.3.1 as the default gateway which isn't right and you do not have a DHCP pool for 192.168.5.0/24.  In addition you have configured "ip helper-address 192.168.2.2" under each interface so it's not clear whether you want this router to be the DHCP server.

It is also not clear what is connected to fa0/0 and fa0/1 ie. is the same switch with vlans on it or separate switches etc.

Can you add some more details.

Jon 

[randy kruen]

Sorry. I am really not an expert here by any means. All I wish is to be able to connect 2 seperate switches to fe0/0 and 0/1 respectively. I may have configured the vlan1 pool incorrectly, I was only guessing as I used vlan2 as a template. But it is working??? I would like both fe0/0 and 0/1 to be able to hand out ip addresses in their own range, and be able to talk to the outside world on the t1 card. Hope that helps?

Randy

[Jon Marshall · Accepted solution]

No need to apologise, just trying to clarify.

So do you want this router to be the DHCP server ? Assuming you do firstly change vlan 1 default gateway to be 192.168.4.1. Then create a new pool for 192.168.5.0/24 with the default gateway as 192.168.5.1.

You also need to exclude those IPs from the DHCP pool so they are not handed out so add this to your configuration -

ip dhcp excluded-address 192.168.3.1
ip dhcp excluded-address 192.168.4.1
ip dhcp excluded-address 192.168.5.1

note you configure the above in configuration mode ie. not under the DHCP scope.

If you don't want this router to be the DHCP server then ignore the above and let me know.

Jon

[randy kruen]

Thanks very much! I'll work on the config. I am sorry if these are very newby questions. But I am having fun doing this, I like playing with Cisco routers and ap's. I do have 1 further question, though. Both fe0/0 and 0/1 seem to default to vlan1. I can create a new pool for fe0/1, but how do I specify to that interface that it use that new vlan pool?

Randy

[Jon Marshall · Accepted solution]

You don't specify it, the router will work it out ie. if the interface IP is 192.168.5.1 then it knows it should use the 192.168.5.0/24 pool.

By the way if this router is meant to be the DHCP server then remove the "ip helper-address 192.168.2.2" command from each interface because it is not needed.

Jon

[randy kruen]

Hi Jon. All is working great now. I can post my final config if needed for others if needed. My questions were very basic i am sure, but you saved me probably hours of headbanging.

Thankyou very much for your help!

Randy

[Jon Marshall]

Randy

No problem and no need to worry about your questions, that is what these forums are for so feel free to post any time you need to.

Glad it's all working now.

Jon

[Reza Sharifi]

Hi,

Maybe not relevant, but why do both pools point to the same gateway?

Is that a typo?

ip dhcp pool vlan1
network 192.168.4.0 255.255.255.0
default-router 192.168.3.1
dns-server 24.153.23.66 24.153.22.67
!
ip dhcp pool vlan2
network 192.168.3.0 255.255.255.0
default-router 192.168.3.1
dns-server 24.153.23.66 24.153.22.67

Also, are you trying to configure one pool for fa0/0 and a different one for fa0/1?

Why do you need two? If you have devices connecting to fa0/1, the helper-address can still be 192.168.2.2

Can you clarify?

HTH