ZyXEL ZyWALL ATP700 User Guide - Page 263
Proxy ARP
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Chapter 9 Interfaces Table 100 Configuration > Network > Interface > Ethernet > Edit (continued) LABEL DESCRIPTION Configure PPPoE/PPTP Click PPPoE/PPTP if this interface's Internet connection uses PPPoE or PPTP or L2TP. Configure VLAN Configure WAN TRUNK Click VLAN if you want to configure a VLAN interface for this Ethernet interface. Click WAN TRUNK to go to a screen where you can set this interface to be part of a WAN trunk for load balancing. Configure Policy Click Policy Route to go to the policy route summary screen where you can manually Route associate traffic with this interface. You must manually configure a policy route to add routing and SNAT settings for an interface with the Interface Type set to general. You can also configure a policy route to override the default routing and SNAT behavior for an interface with an Interface Type of internal or external. OK Click OK to save your changes back to the Zyxel Device. Cancel Click Cancel to exit this screen without saving. 9.4.2 Proxy ARP An Address Resolution Protocol (ARP) is a protocol for mapping an IP address to a MAC address. An ARP broadcast is sent to all devices on the same Ethernet network to request the MAC address of a target IP address. In the following figure, a host in a WAN subnet (A) broadcasts an ARP request to all devices within its network in order to find the MAC address of a target IP address (172.16.x.x). However, the target IP address may be in another subnet (B) that has the same network IP address (172.16.x.x). A router, such as the Zyxel Device, does not forward broadcasts, so the request will not reach its destination. Enable Proxy ARP (RFC 1027) to allow the Zyxel Device to answer external interface ARP requests on behalf of a device on its internal interface. Interfaces supported are: • Ethernet • VLAN • Bridge The Zyxel Device sends its external MAC address to the WAN sender as the destination for the target IP address. From then on the sender will send packets containing that target IP address directly to the external interface of the Zyxel Device. The Zyxel Device then forwards the packet to the correct target IP address in its LAN. Figure 200 Proxy ARP 172.16.x.x 172.16.x.x ZyWALL ATP Series User's Guide 263
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