VLAN 1

[Grenage]

Hi again,

I'm not very familiar with VLANs at all, I know that they are designed to stop broadcast traffic flooding from one point to another.

Does this mean they will stop DHCP Broadcasts too ? (I am assuming yes)

 

[rwullems]

Not neccesarely. The broadcast traffic will travel in the specific VLAN. So if you put a IP subnet in a VLAN, all broadcasts send out by stations in that specific VLAN will travel trough that VLAN.

So, to make sure that DHCP works, you must make sure that either there is a DHCP server on the same VLAN or that there is a DHCP relay agent available to let the DHCP traffic pass a router to another subnet where you DHCP server is located.
Regards,
Robert

Robert A.H. Wullems
Sniffer University Instructor
SCM / CNX / MCP
Citee Education
the Netherlands

 

[Grenage]

Thankyou Kindly

 

[markpower]

Useful one if you have your DHCP or BOOTP servers in another subnet (VLAN) from your users is the ip helper address command. This will forward any broadcast traffic from the clients towards the servers on another subnet. On Cisco the syntax is:

enable
conf t
interface vlan1
ip helper-address w.x.y.z

You can add multiple servers.

 

[rwullems]

Hi agree with you on that one, but it is the same as what microsoft calles an DHCP relay agent. Cisco uses a different baming

Robert A.H. Wullems
Sniffer University Instructor
SCM / CNX / MCP
Citee Education
the Netherlands