Cisco Catalyst Express 500 - DHCP Relay

Unanswered Question
Feb 24th, 2010

I wanted to know if DHCP relay is supported on the CCE 520? I believe the answer is no since that feature will require "IP Helper-Address" which requires a layer 3 switch and the CCE is layer 2 only. Basically, I want to connect IP Phones and PC's on two different VLAN's and use a DHCP server to do this.

Will this be a problem with this type of switch (layer 2) or will I require a L2 / L3 switch?

Any feedback is welcomed.

Thanks.

I have this problem too.
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Overall Rating: 4 (3 ratings)
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Reza Sharifi Wed, 02/24/2010 - 16:50

Hi John,

You would need a layer-3 device to route between for example 2 PC vlans.  Do you have router? how many devices and also subnet/vlan do you have?

Also, the helper address would go on the router interface.

HTH

Reza

John Torkos Wed, 02/24/2010 - 17:12

Thanks your reply. The design is that 2 VLAN's will be required per location; one for the IP phones and the other for their data.Please see below. Each location will have it's own DHCP server. Would a L3 switch still be required?

PC --- IP Phone --- Switch (Vlan 10 & 20) --- Router (802.1q trunking) ---- MPLS cloud --- Router  (802.1q trunking) --- Switch (VLAN 10 & 20) --- IP Phone --- PC

Reza Sharifi Wed, 02/24/2010 - 17:53

John,

Yes, is this case the router at each location should have a helper address pointing to the local DHCP server.

Why do you have the same vlan ids on both side?  is this a layer-2 VPN?

HTH

Reza

John Torkos Wed, 02/24/2010 - 19:08

Thank you for the response. I will purchase additional L2 / L3 switches then for each location. The VLAN IDs were for demonstration purpose to illustrate what it looks the network looks like.

Thanks again.

John

Jon Marshall Fri, 02/26/2010 - 06:26

p.bevilacqua wrote:

You do not need additional switches for that.

The router will do just fine.

Hmmm, i'm really not sure why this was rated a 1 as it is exactly right. The routers at each site that are already there could be used to do routing on a stick between the internal switches and the internal interface of each router.

I've rated this a 5 to try and rebalance but it would be nice if whoever rated the post a 1 could explain why it was not helpful.

Jon

Paolo Bevilacqua Fri, 02/26/2010 - 06:37

Thank you Jon.

Unfortunately it's too easy to low-rate anonimously and without a reason.

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