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Cisco Catalyst Express 500 - DHCP Relay

John Torkos
Level 1
Level 1

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.

7 Replies 7

Reza Sharifi
Hall of Fame
Hall of Fame

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

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

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

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

You do not need additional switches for that.

The router will do just fine.

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
Hall of Fame
Hall of Fame

Thank you Jon.

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

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