Simple VLAN question

Unanswered Question
singhsaju Wed, 10/08/2008 - 11:56

You will need , "ip helper-address "

Directs the broadcast request as unicast to dhcp server.

For example:

interface Vlan112

ip address

ip helper-address



Pls rate helpful posts

Jon Marshall Wed, 10/08/2008 - 13:23


No need to apologize, that is what NetPro is for.

There are basically 2 ways to assign IP address to devices within a vlan

Note - usually there is a one-to-one relationship between a vlan and an IP subnet.

1) Assign them manually on each end device which is time consuming but for things like servers is generally what you do.

2) Assign them dynamically as Saju has covered in his post. You set up an IP subnet within a DHCP server and the DHCP server hands out IP addresses within the subnet to devices. Generally DHCP is used for client workstations/laptops.


franklinb Wed, 10/08/2008 - 20:26

Additionally, if you want to use PXE-boot with DHCP on those VLANs:

We needed to add another line since our PXE server has a different address:

int vlan x

ip address <>

ip helper-address

ip helper-address

ip directed-broadcast


access-list permit udp host any eq 402

ip forward-protocol udp 402

* 402 might be incorrect for other PXE implementations. This was for Altiris


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