Multiple Vlan on 6024 and Single DHCP Server

Question

I have 2 vlans set up and i have workstations plugged into them. None of the workstations are getting ip address from the DHCP server located at 192.168.1.250.

I have the server plugged into port 8 on the router. I have the scopes set up on my server. What is wrong with my configuration? And if the config is right, then how do i confirm that my DHCP scopes are correctly set up?

Router Configuration
-----------------------------

vlan database
vlan 2-3
exit
interface range ethernet g(1-2)
switchport access vlan 2
exit
interface range ethernet g(3-4)
switchport access vlan 3
exit
interface vlan 2
name Test1
exit
interface vlan 3
name Test3
exit
interface vlan 2
ip address 192.168.2.1 255.255.255.0
interface vlan 3
ip address 192.168.5.1 255.255.255.0
exit
ip dhcp relay address 192.168.1.250
ip dhcp relay enable
router rip enable
username aotadmin password xxxxxxxxxxxxxxxxxxxxxxxxx level 15 encrypted
snmp-server community Dell_Network_Manager rw view DefaultSuper

drgnslyr · Answer

the config looks good.    Sorry, ihave no input for the DHCP server portion.

lam_tran5582 · Answer

This might be a stupid question but do i have to plug the dhcp server in and particular port?

mandzo · Answer

To open the IP Static Route page, click Router→ Global Routing Parameters→ IP Static Route or the CLI command: ip route prefix {mask | prefix-length} gateway [metric distance] [reject- route]

mandzo · Answer

hi Lam, this link might be helpfull: www.dell.com/downloads/global/products/pwcnt/en/app_note_38.pdf I also think you may need to tell the router how to reach the DHCP server, something like a static routing

lam_tran5582 · Answer

i followed the directions there to create the config file i posted above. I thought that when you enable dhcp relay and give it the dhcp server address, that creates the route.   My computer are getting ip address, just not the correct ones for their subnet.   How do i create the static route from the router to the server?

lam_tran5582 · Answer

I think  there is a problem with the configuration on the DHCP server.   Could someone point me in the right the direciton as how to have the DHCP server set up?

scheesman · Answer

Is it just me, or is port 8 not assigned to a VLAN?  It should trunk VLANs 2 and 3 to your server.  Then, if your server has the VLANs configured, you should be able to assign IP's to them and the DHCP server should assign IP's based on the incoming VLAN.  Plus the IP you have assigned for your DHCP forwarder doesn't exist on any defined VLANs.

lam_tran5582 · Answer

mandzo,   Currently i'm having trouble with all of the vlans.   I wanted to start small and just have 2 vlans and the default config vlan. Instead of using my 2 additional switches, I have have 2 laptops plugged into the 6024 into each vlan with different subnets.   I assumed that if you have vlan relay enabled and you type in address of the dhcp server, then the router would be able to figure which port it was plugged into. I can get the vlans to find the server, but they're not being assigned the correct addresses. I   Another question is, i know my OOB port is configured to be . 240 , do i need to assign an ip address to the router itself? if so, how do i do it?   I may be missing something that is making the vlan routingnot work.

mandzo · Answer

Hi Lam, you have multiple VLANs - 2,3,111,... etc + management VLAN 1 How many VLANs do you have a problem with?

DRNO10 · Answer

This should be pretty straight forward, let me give you an example.

You have 3 subnets,

Subnet a - 10.10.10.0

Subnet b - 10.10.20.0

Subnet c - 10.10.30.0

Subnet a is for clients, Subnet b is for clients, Subnet c is for the dhcp server

Setup vlan 10,11,12 on the switch assinging vlan interfaces as follows

vlan 10 - 10.10.10.1 (subnet a)

vlan 20 - 10.10.20.1 (subnet b)

vlan 30 - 10.10.30.1 (subnet c)

to keep it simple setup port 1 to access vlan 10, port 2 to vlan 20 and port 3 to vlan 30.

your DHCP server would be 10.10.30.2 with its default gateway pointing to 10.10.30.1. Plug it into port 3

add the server ip to the DHCP helper address in the switch

on the DHCP server create 2 scopes

scope 1 - 10.10.10.2 - 10.10.10.254 on a /24 subnet. Setup the default gateway to 10.10.10.1

scope 2 - 10.10.20.2 - 10.10.20.254 on a /24 subnet. Setup the default gateway to 10.10.20.1

Now, you shouldnt have to touch routing tables. By default when a local interface comes up on the 6024 the switch will route it (unless you have ACL's setup).

Now when you plug a client into port 1 or port 2 the switch should relay the DHCP request to the DHCP server which will reply with an address from the appropriate pool based on the routing interface on the switch it came from.

From what i see in your initial post you dont have a vlan with the DHCP server in it setup, so the switch doesnt know where to forward the packets. Try the above scenario it should work fine.

Message Edited by DRNO10 on 01-22-2008 04:27 PM

Message Edited by DRNO10 on 01-22-2008 04:28 PM

lam_tran5582 · Answer

DRNO10,     THANKS A LOT ! My DHCP was misconfigured.

lam_tran5582 · Answer

Dr No,

I seem to still need some of your assistance.

Currently i have the 6024 configured with 6 VLANs:

1

100 192.168.1.1

400 192.168.4.1

500 192.168.5.1

600 192.168.6.1

700 192.168.7.1

i have 2 ports that combine to form a Lag. This Lag is part of every vlan.

I have the 6024 connected to a 3448 switch using the lag.

the 3448 have vlans configured all with the lag as a member. The vlan members on the switch are getting the corrected ip address based on the ip address of the vlan. But, all of the computers can ping each other. Doesn't it defeat the point of vlans if all of the computer can communicate with each other? Or am i utilizing the lags incorrectly?

Message Edited by lam_tran5582 on 01-31-2008 03:24 PM

Message Edited by lam_tran5582 on 01-31-2008 03:24 PM

DRNO10 · Answer

By default on the 6024 when the routing interfaces come up it allows full routing between all interfaces. Now as pointless as that seems, this still keeps the subnet broadcasts and snooping contained within each specific vlan unless the person knows the ip they want to connect to.   The beauty of having the 6024 at the core handling your routing is you can control of the traffic crossing the interfaces. You can lock things down and only allow specific port/ip ranges ect to certain vlans using ACL's(access control lists). One thing to remember is on the 6024 ACL's are applied to the ingress traffic as it enters the vlans not egress. the 62XX series allows both ingress and egress traffic ACL's.

Rob_Henry · Answer

That was a great tutorial. I am looking to setup the same thing. My only difference is I don't know what port each person will connect to and some users may go from one office to the other but need to remain on the same VLAN. Can this be done some how. Where only there IP address will decide what VLAN they are on?

Thanks

Rh

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Multiple Vlan on 6024 and Single DHCP Server

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