DHCP help between 2 switches

[Andy White]

Hello,

I have a L2 switch and L3 swithch trunked.  There are multiple VLANs on these switches but I want the L3 switch to be able to give DHCP offers to all these VLANs in the L2 switch and L3.  I have created the 5 DHCP scopes on the L3 switch, but the L2 switch doesn't get them. 

For example I have VLAN 10 on both switches and have created a DHCP scope for 192.168.23.x/23  the PC's in VLAN 10 don't get an IP.  Do I have to use relay on the trunks, how does VLAN 10 know it should be getting an IP address from that scope and not another?

THanks

[Andy White]

Think I have it.  I had to create L3 interface for the VLANs on the L3 switch.

[edondurguti]

If u have multiple vlans you need multiple vlan interfaces on L3 switch to act as a gateway for pcs/hosts. That way hosts on vlan3 will know which address to get based on their gateway

Sent from Cisco Technical Support iPhone App

[Abzal]

Hi,

Few things to consider:

1. Check if the PC on right VLAN

2. Port between L2 switch and L3 switch need to be configured as a trunk and it need to allow these VLANs.

3. L3 switch with DHCP scope configured on it knows which scope select by gaddr field. On that field L3 switch puts it's VLAN IP address on which it received DHCP packet from PC.

Hope it will help.

Best regards,
Abzal