topic Re: multiple vlan with different DHCP pool in ICX Switches

multiple vlan with different DHCP pool

daniel_ling_i7i — Thu, 25 Apr 2019 09:39:56 GMT

Hi Guys,

I need some help, i am using an 7450-24p with an router image running on version 08.0.80e.

i enable dhcp server on the switch. i am trying to have 2 vlans with different ip subnet.

below is my config, did i miss or do anything wrong over here? as i am not able to get any ip from it.

show run

Current configuration:
!
ver 08.0.80eT213
!
stack unit 1
module 1 icx7450-24p-poe-port-management-module
module 2 icx7400-xgf-4port-40g-module
module 3 icx7400-qsfp-1port-40g-module
module 4 icx7400-qsfp-1port-40g-module
!
global-stp
!
vlan 1 name DEFAULT-VLAN by port
spanning-tree
!
vlan 10 name IP-subnet_192.168.1.0/24 by port
untagged ethe 1/1/1 to 1/1/12
router-interface ve 10
spanning-tree
!
vlan 20 name IP-subnet_192.168.2.0/24 by port
untagged ethe 1/1/13 to 1/1/24
router-interface ve 20
spanning-tree
!
ip dhcp-server pool wifi
excluded-address 192.168.1.1 192.168.1.10
lease 1 0 0
network 192.168.1.0 255.255.255.0
option 3 ip 192.168.1.1
option 6 ip 8.8.8.8
deploy
!
ip dhcp-server pool smart
excluded-address 192.168.2.1 192.168.2.10
lease 1 0 0
network 192.168.2.0 255.255.255.0
option 3 ip 192.168.2.1
option 6 ip 8.8.8.8
deploy
!
interface ve 10
port-name wifi
ip address 192.168.1.1 255.255.255.0
!
interface ve 20
ip address 192.168.2.1 255.255.255.0

Re: multiple vlan with different DHCP pool

BenBeck — Thu, 25 Apr 2019 14:25:39 GMT

Hey Dan,

Do you have "ip dhcp-server enable" in your configuration? It is a global command.

Re: multiple vlan with different DHCP pool

eric_pouliot — Thu, 25 Apr 2019 14:55:43 GMT

Maybe you could try adding an "ip helper-address" to the ve interface.
That's what I use, but my dhcp server is external.

Re: multiple vlan with different DHCP pool

BenBeck — Thu, 25 Apr 2019 15:00:32 GMT

He shouldn't need that here since he is serving directly attached vlans. If the server was on an external network like you mentioned, then we would use a helper.

Re: multiple vlan with different DHCP pool

daniel_ling_i7i — Thu, 25 Apr 2019 15:38:30 GMT

Hi Ben, Yes dhcp-server is enable.

Re: multiple vlan with different DHCP pool

BenBeck — Thu, 25 Apr 2019 15:46:35 GMT

Interesting. I don't see anything wrong in your configuration although it is just a snippet. Are you learning mac-addresses probably on the ports? "show ip dhcp-server summary" and "show ip dhcp-server binding" should give you a clue about whether the switch is trying to serve addresses.

Re: multiple vlan with different DHCP pool

daniel_ling_i7i — Thu, 25 Apr 2019 15:54:09 GMT

yea i dont get it why is not working... i will get "show ip dhcp-server summary" and "show ip dhcp-server binding" to show you when i am back to office.. anything else i should check?

Re: multiple vlan with different DHCP pool

andrew_giancol1 — Thu, 25 Apr 2019 16:04:30 GMT

If you plug a TAP (Wireshark or your preferred sniffer) into a untagged Vlan 10, or vlan 20 port, are you seeing your target device's DHCP Requests? This is where I'd go now. try and see if DHCP is responding with a NAC, or if your Target device is being outright ignored, or isn't seen. Can you produce a scenario where DHCP works on this switch at all?

Re: multiple vlan with different DHCP pool

BenBeck — Thu, 25 Apr 2019 16:04:30 GMT

Hard to say off just that configuration. I see you are on old spanning tree (802.1d). You may want to move to 802.1w for faster convergence as 802.1d is pretty slow.The command is "span 8" at the vlan level. "show log" should also give you some clues as to if the switch is trying to give out addresses. If we can't get a clue out of these outputs, it may just be easier to open a case and have an engineer look at it with you.

Re: multiple vlan with different DHCP pool

abilashpr — Thu, 25 Apr 2019 18:04:47 GMT

Hi Dan,

Upon checking the configuration which is given above it looks like you have not enabled DHCP globally that is the reason why its not working.

If globally if it is enabled, we should see that in the configuration as below.

aaa authentication web-server default local
aaa authentication login default local
enable telnet authentication
enable aaa console
hostname MDF-CORE
ip dhcp-server enable
!
ip dhcp-server pool 1
dhcp-default-router 192.168.8.100
dns-server 8.8.8.8 8.8.4.4
excluded-address 192.168.8.99 192.168.8.140
lease 0 4 0
network 192.168.8.0 255.255.252.0
deploy
!
!
ip dhcp-server pool 206
dhcp-default-router 10.206.0.1
dns-server 8.8.8.8 8.8.4.4
excluded-address 10.206.0.1
excluded-address 10.206.0.25
lease 0 0 5
network 10.206.0.0 255.255.224.0
deploy
!
!
ip dhcp-server pool 207
dhcp-default-router 10.207.0.1
dns-server 8.8.8.8 8.8.4.4
excluded-address 10.207.0.1
lease 0 0 10
network 10.207.0.0 255.255.224.0
deploy

Regards,
Abilash PR.

Re: multiple vlan with different DHCP pool

daniel_ling_i7i — Fri, 26 Apr 2019 04:26:41 GMT

omg thanks Abilash! stupid me i turn on dhcp-client instead of server hahaha it works now thanks!!

Re: multiple vlan with different DHCP pool

daniel_ling_i7i — Fri, 26 Apr 2019 04:27:31 GMT

got it working thanks to Abilash... i turn on dhcp-client instead of server hahah... thanks ben!