Email Subscription Notifications Suspended Temporarily
We are in the process of making navigation in the Servers and Operating Systems forums simpler and more direct. While doing this, we have to temporarily suspend email notifications for subscriptions. If you are subscribed to one or more discussion boards or blogs in the community, please check them daily to see new content. Notifications will be turned back on in a few days. We apologize for any inconvenience this may cause. Thanks, Warren_Admin
Switches, Hubs, and Modems
Showing results for 
Search instead for 
Did you mean: 

DHCP across VLAN

Ramon Beringer
Occasional Advisor

DHCP across VLAN

i am in big trouble here getting DHCP Responses across my 3500yl. I am now in the situation that i have 1 PC in VLAN 101 ( discovering for an DHCP Address via Broadcast. Then the 3500yl forward that packet via Unicast to my DHCP Server in my Default VLAN 1 ( Thats the good thing.

Then my DHCP Server is sending an DHCP Offer via BROADCAST but the 3500yl don't catch that Packet and move it into my VLAN 101.

Should the DHCP Server not response with an Unicast to my Switch?

Any "sh dhcp-relay" on my 3500 shows 0 0 0 0

LHG-HUB283# sh run

Running configuration:

; J8693A Configuration Editor; Created on release #K.12.57

hostname "LHG-HUB283"
web-management management-url ""
time timezone 60
time daylight-time-rule Middle-Europe-and-Portugal
module 1 type J86yyA
module 2 type J86xxA
module 3 type J8694A
ip routing
vlan 1
untagged 1-A4
ip address
vlan 101
name "WLAN-IM"
ip helper-address
ip address
tagged 1,A1-A2
ip route
router ospf
area backbone
spanning-tree priority 5 force-version RSTP-operation
vlan 1
ip ospf area backbone
vlan 205
ip ospf area backbone


Thank you for any help,
Best Regards,
Ramon Beringer
Occasional Advisor

Re: DHCP across VLAN

I found the Error, it seems that Configuration don't work with Tiny DHCP Server V1.3. I take another DHCP (Linux) and now it works perfect.

cenk sasmaztin
Honored Contributor

Re: DHCP across VLAN

hi Ramon

so you dhcp server in vlan 1 must be
ip address
subnet musk:
default gateway :
and connect switch on vlan 1 untag port

and you create on dhcp scobe for vlan 101
scobe name vlan 101
ip range
subnet mask:
default gateway:

and you write ip helper address on vlan 101
ip helper-address nic address)
and ip routing enable on switch .