Three switches, two routers and a VLAN question

coleman.e · ‎05-08-2012

I'm working at a client site that uses two seperate routers, switches (non Cisco) and ISPs for their VoiP and Data traffic. The only common connection between the two LANs is one Windows server that runs DHCP via a 2 port nic thats connected to each switch.

They're expanding into a new part of their building and a new Cisco SGE2000p has been installed. Two drops, one from each switch have been run into the expansion area. My goal is to segment the ports on the SGE2000p into two seperate VLANs, so that ports 1-12 connect to the Data switch and ports 13-24 connect to the Voice switch. I've tried this multiple times but I can't get DHCP traffic to flow over both vlans, it always ends up working on only one of the two, whichever is the first VLAN that's configured.

Here's my current config:

VLAN100:Port 1 connected to Data switch. Ports 2-12 untagged members, computers connected. Recieves DHCP from server.

VLAN200:Port 13 connected to VoiP switch. Ports 14-24 untagged members, phones connected. Doesnt recieve DHCP from server.

DHCP relay enabled and pointed to the DHCP server.

Both phones and data are on the same 10.10.10.0/24 subnet.

Neither VLANs have IPs assigned to them.

There are no VLANs on the 2 origional switches.

Where am I going wrong here?

I've attached a diagram and your help is greatly appreciated!

Richard Burts · ‎05-08-2012

A little more detail about how the new SGE2000p is configured might be helpful, especially how DHCP relay is set up. But as I read this description I believe that one problem may be trying to have the same subnet on both VLANs.

HTH

Rick

HTH

Rick

coleman.e · ‎05-08-2012

Thanks Rick,

Under the DHCP Relay tab on the SGE200p, I've enabled DHCP Relay and added the IP address of the DHCP server. I dont have many other options that can be changed there.

Also, the configuration works the same (DHCP on one VLAN, no DHCP on the other) whether DHCP Relay is enabled or not.

Richard Burts · ‎05-08-2012

Can you tell us a bit about ports 1 and 13? Are they configured as plain access ports in the particular VLAN? Does the SGE2000p believe that it is doing any trunking?

And am I understanding correctly that if you take away VLAN 100 that the existing VLAN 200 will receive DHCP without changing anything on the new switch?

HTH

Rick

HTH

Rick

coleman.e · ‎05-08-2012

Ports 1 and 13 are currently configured as plain Access ports. I've tried configuring them as Trunking ports whiles maintining VLAN membership but that makes no difference.

No, no matter what only the very first manually created vlan will ever transmit DHCP traffic.

If I switch the drops between the two ports (1 and 13) same result, VLAN 100 gets DHCP via the origoinal VoIP switch.

If I delete VLAN 200 and have only the default VLAN (VLAN1) and VLAN100, no members of VLAN1 will get DHCP either.

Richard Burts · ‎05-08-2012

That is very interesting and a bit puzzling to me. Perhaps we need someone who has more expertise than I do with SGE2000p to find the explanation for this.

HTH

Rick

HTH

Rick

coleman.e · ‎05-09-2012

Bump for additional feedback. Thanks!