6-38 CHAPTER 6: M ANUAL SETUPMAC-EncapsulatedRoutingBecause routers base their forwarding decision on network-level addresses,packets that are routed over a WAN are transmitted without MAC-layer addresses.Additionally, address resolution procedures that can be used to determine thedestination MAC address for a packet are not required.Conversely, packets that are bridged over a Wide Area Connection includeMAC-layer information. Address resolution procedures are required.MAC-Encapsulated Routing uses network-level addresses for forwarding decisionsbut transmits MAC-layer addresses over the Wide Area Connection. Additionally,address resolution procedures are used. To the remote site, the packets appear asif they had been bridged.This feature allows the routing features of the OCR 812 (i.e., address translation,DHCP Server, DNS Proxy, etc.) to be employed in a bridged environment.ConfiguringMAC-EncapsulatedRoutingMAC-Encapsulated Routing is specified on a per-VC basis. WhenMAC-Encapsulated Routing is enabled in a VC profile, packets for the routedprotocols configured by the profile (i.e., IP and/or IPX) will be sent using theappropriate bridged encapsulation. If the configured network service is RFC 1483,then the packets will be encapsulated in a bridged-1483 format. If the configuredservice is PPP, the packets will be encapsulated in BRCP. To enable MAC-Encapsulated Routing in a VC profile, use the command:set vc mac_routing enable To disable the MAC-Encapsulated Routing in a VC profile, use the command:set vc mac_routing disableSimultaneousBridging andRoutingThe OCR 812 can be configured for simultaneous bridging and routing. IP routingis configured if IP forwarding is enabled (see Enabling IP Routing). IPX routing isenabled if an IPX network is present over the Ethernet interface (see ConfiguringIPX for the LAN). Bridging is enabled by adding a bridge network over the Ethernetinterface. (see Configuring Bridging for the LAN). Routing and bridging areenabled for each destination in its remote site profile.When configured for simultaneous bridging and routing, packets received fromthe LAN are first passed through the router for any configured protocols. If thepacket can not be routed it is passed to the bridge depending on the setting of theBridge Firewall function.The Bridge Firewall has three modes:1 Discard Routed Protocols:This is the default mode. If a protocol is configured for routing and a packet forthat protocol type is received from the LAN that is not addressed to the MACaddress of the OCR 812, it is discarded. Additionally, broadcasts (including ARPs)for the protocol are not passed to the bridge. To configure the Bridge Firewall forthis mode, use the command:set bridge firewall discard_routed_protocols
