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Beginner

Invisible DHCP

Hey again!

And again: sorry for my lack of english skills if something is missunderstanding.

I have two Windows 2016 Servers on a virtual machine on one pc. These Servers are connected to a Cisco SG350 Switch. Beside other services there runs a DHCP on each server, because they have different domains and IPs. One is the 198.168.1.XX (domain A) and the other 192.168.2.XX (domain B).
To the Switch are also connected to Laptops, my clients. Both must get the IPs automatically from the DHCP. My task is that each of the clients must go automatically in the right domain. One in domain A and the other in domain B.
My newest position is that both of the clients go automatically in the same domain. But this is not my destiny.
I have no settings in my switch, because I don't know if I can solve this problem with vlans or anything else.
Someone gave me the hint that the wrong DHCP should be invisible for each client. Someone sad I can to this with the DHCP-relay, like to say my switch "you can give the client to this VLAN this DHCP and the other client through another VLAN the DHCP". But I read about DHCP-realy and I found out this is more about to go over different subnets with one DHCP and this would be no solution for me.
So maybe some of you can help me.
Thank you!

Everyone's tags (4)
5 REPLIES 5
Participant

Re: Invisible DHCP

hi

you will need dhcp-relay to forward the DHCP Discover packet from each client in its own vlan to the correct DHCP server

i dont deal with SG switches but the concept should be the same

as an example

pc in vlan 2 - switch needs routed interface for vlan 2 - then use dhcp-relay to point to dhcp server for vlan 2

pc in vlan 3 - switch needs routed interface for vlan 3 - then use dhcp-relay to point to dhcp server for vlan 3

the server will check the subnet it received the request from and assign an IP for that scope

regards, mk

please rate if helpful or solved :)

Beginner

Re: Invisible DHCP

For a reason I don't know your solution doesn't work. Now I can't reach the active Directory from any Laptop.
Well, here is my configuration on the Switch. Pls ignore the other VLANS. 

config-file-header

switchd16938

v2.3.5.63 / RLINUX_923_093

CLI v1.0

file SSD indicator encrypted

@

ssd-control-start

ssd config

ssd file passphrase control unrestricted

no ssd file integrity control

ssd-control-end cb0a3fdb1f3a1af4e4430033719968c0

!

unit-type-control-start

unit-type unit 1 network gi uplink none

unit-type-control-end

!

vlan database

vlan 2-3,9,11

exit

voice vlan oui-table add 0001e3 Siemens_AG_phone________

voice vlan oui-table add 00036b Cisco_phone_____________

voice vlan oui-table add 00096e Avaya___________________

voice vlan oui-table add 000fe2 H3C_Aolynk______________

voice vlan oui-table add 0060b9 Philips_and_NEC_AG_phone

voice vlan oui-table add 00d01e Pingtel_phone___________

voice vlan oui-table add 00e075 Polycom/Veritel_phone___

voice vlan oui-table add 00e0bb 3Com_phone______________

ip dhcp relay address 192.168.1.2

ip dhcp relay address 192.168.2.2

bonjour interface range vlan 1

hostname switchd16938

!

interface vlan 2

 name IT-AB

 ip address 192.168.0.28 255.255.255.0

!

interface vlan 3

 name IT-Test

 ip address 192.168.1.28 255.255.255.0

!

interface vlan 9

 name Test-AB

 ip dhcp relay enable

!

interface vlan 11

 name Test-Campus

 ip dhcp relay enable

!

interface GigabitEthernet1

 spanning-tree portfast

 switchport access vlan 2

!

interface GigabitEthernet3

 spanning-tree portfast

 switchport access vlan 3

!

interface GigabitEthernet9

 spanning-tree portfast

 switchport access vlan 9

!

interface GigabitEthernet11

 spanning-tree portfast

 switchport access vlan 11

 

Rising star

Re: Invisible DHCP

the solution with dhcp relay is for the config where you got a single dhcp server for both dhcp scopes,

not for two independent dhcp servers

Participant

Re: Invisible DHCP

dhcp-relay will just forward the packet to any dhcp server IP - so you can have more than 1 configured

regards, mk

Rising star

Re: Invisible DHCP

start with your host where the VMs are running

here each VM needs to configure the VNIC to the right VLAN

you physical network card needs a driver that supports vlans to pass this to the outside, else you need two different NICs

 

 

using a single NIC with vlans your switchport that connect to the host needs to bo configured as a vlan-trunk

on the switch you separate the vlans again by assigning a port as accessport for this vlan

 

interface GigabitEthernet1

description client in vlan 2

 spanning-tree portfast

 switchport access vlan 2

!

interface GigabitEthernet3

 description client in vlan 3

 spanning-tree portfast

 switchport access vlan 3

!

interface GigabitEthernetx

 description host where VMs are running

 switchport mode trunk

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