VLANs and DHCP

[Jawloms]

• I’ve created a new VLAN 8 on my core switch. I’ve given it an IP address of 10.161.8.1 and a SM of 255.255.255.0.

• My Windows DHCP server is 10.161.2.11. (SM 255.255.254.0)

• My internet router which is the DG for the entire network atm is 10.161.2.1. (SM 255.255.254.0). My goal ultimately is to get the switch to be the DG rather than the Internet router, but that's for another day.

• My core switch (which is set to route traffic) is 10.161.2.2. (SM 255.255.254.0)

• I’ve setup an additional DHCP scope on my server for 10.161.8.x.

• I’ve untagged a port on my core switch into VLAN 8.

• On my switch on VLAN 8 I’ve put an ip helper-address of 10.161.2.11.

 

When I plug a laptop into the untagged port it doesn’t get an IP address. The server itself isn’t tagged or untagged in any VLANs but I didn’t think it needed to be because IP routing is on, and the ip helper-address is there. If I specify an IP address on the laptop of 10.161.8.5 with a DG of 10.161.8.1, I can ping 10.161.8.1 (VLAN 8) and 10.161.2.2 (Core switch default VLAN IP), but nothing else. How come it’s not getting an IP? What did I miss?

 

Thank you

 

Stuart

[FN-GM]

Just to check. You cannot ping the DHCP server from the laptop with the static IP. If not I suspect your DHCP server is using 10.161.2.1 as the DG. If so that router will not have any routes to the new VLAN subnet so the traffic is getting dropped.

[Jawloms]

Spot on. DG changed on the DHCP server and all is working now. Thank you.

[FN-GM]

Brill. Thanks for letting us know.