Bridging and Routing

Routing

You can configure the Megabit Modem 400F router to route Ethernet-encapsulated

IP datagrams based on IP addresses. Use Routing Information Protocol (RIP) to automatically identify the route from the session on the Megabit Modem 400F to the destination. You can specify the direction and version of RIP that allows other routers to update their routing tables automatically (for example, information on how many hops between destinations). The version of RIP you select for the session must match the version supported by the service provider. Versions RIP1 and RIP-1 compatible are used for broadcast. Version RIP 2 is used

for multicast.

The router also learns addresses. In addition to the addresses it learns, you can add 32 static route entries on the LAN Brouter configuration page. Through the static IP routing feature, you can configure the Megabit Modem 400F as an IP router with statically programmed route entries. You can enable this function to provide broadcast filtering and to prevent eavesdropping by specifying multiple destination gateways. When static IP routing is enabled, you can access only specific remote IP subnets or hosts.

Since IP routers make forward or filter decisions based on the network-layer IP address instead of the MAC hardware address, MAC-level broadcast frames are prevented from reaching unwanted destinations in the network.

When setting parameters for an external router, configure a Static Route entry in any of the external routers that may have been specified as a Default Router or as a Gateway. This implementation prevents other parties from discovering routes through eavesdropping. The format of this entry varies among the various router vendors, but is typically in the form of "Destination," "Mask," and "Gateway," where the "Destination" is the remote IP Subnet or host address, and "Gateway" is the IP address of the modem on the same subnet as the external router.

Encapsulation for RFC 1483 Bridging/Routing

Most users select LLC, which allows you to run multiple protocols over the VC. An encapsulation header identifies the types of protocol being carried in the transmission (for example, IP). VC-MUX allows only one protocol to run over the VC. The type of protocol must be negotiated between the modem and the service provider prior to the transmission. Because there is only one protocol allowed, the header is not required. This configuration is normally setup by the service provider.

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Megabit Modem 400F User Manual