Configuring Dhcp Relay - Ruckus Wireless ZoneDirector 1100 User Manual

Configuring DHCP Relay

ZoneDirector's DHCP Relay agent improves network performance by converting DHCP broad-
cast traffic to unicast to prevent flooding the Layer 2 network (when Layer 3 Tunnel Mode is
enabled -- DHCP Relay only applies to Tunnel Mode WLANs.)
Typically, when mobile stations acquire IP addresses through DHCP, the DHCP request and
acknowledgement traffic is broadcast to any devices in the same Layer 2 environment. With
Tunnel Mode WLANs, this traffic flood is wasteful in terms of bandwidth and computing power.
When DHCP Relay is enabled on a WLAN, the ZoneDirector relay agent converts DHCP
Discover / Request traffic to unicast UDP packets and sends them to the DHCP servers, then
delivers DHCP Offer / Ack messages from the DHCP server back to the client.
The traffic flow is as follows:
1. Client sends DHCP discover broadcast.
2. AP tunnels this DHCP discover frame to ZoneDirector.
3. DHCP Relay Agent sends unicast DHCP discover packet to DHCP server.
4. DHCP server sends DHCP offer to Relay Agent on ZoneDirector.
5. ZoneDirector sends DHCP Offer back to the AP.
6. AP sends this Offer to client.
By reducing broadcast flooding, this option allows for higher client capacity in tunneled WLANs
designed for VoIP phones, for example. It also allows for DHCP discovery across multiple
subnets and limits DHCP broadcasts to client's AP tunnel and radio.
To configure DHCP Relay for tunneled WLANs
1. Go to Configure > DHCP Servers.
2. Click Create New.
3. Enter a Name and IP address for the server.
4. Click OK to save your changes. The new server appears in the list.
To enable DHCP Relay for a WLAN
1. Go to Configure > WLANs.
2. If creating a new WLAN, click Create New. Otherwise, click Edit for the WLAN you want
to configure.
3. Under Advanced Options, when Tunnel Mode is enabled, the DHCP Relay option becomes
available.
4. Under DHCP Relay, select Enable DHCP relay agent with __ DHCP server and select the
server you created earlier from the list.
5. Click OK to save your changes.
Configuring System Settings

Configuring DHCP Relay

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