ZyXEL Communications 110, 1100, 310 9.4 Policy Routing Technical Reference

Chapter 9 Policy and Static Routes

The following table describes the labels in this screen.

Table 70 Configuration > Network > Routing > Static Route > Add

LABEL	DESCRIPTION
Destination IP	This parameter specifies the IP network address of the final destination. Routing is
	always based on network number.
	If you need to specify a route to a single host, enter the specific IP address here and use
	a subnet mask of 255.255.255.255 (for IPv4) in the Subnet Mask field or a prefix of 128
	(for IPv6) in the Prefix Length field to force the network number to be identical to the
	host ID.
	For IPv6, if you want to send all traffic to the gateway or interface specified in the
	Gateway IP or Interface field, enter :: in this field and 0 in the Prefix Length field.
Subnet Mask	Enter the IP subnet mask here.
Prefix Length	Enter the number of left-most digits in the destination IP address, which indicates the
	network prefix. Enter :: in the Destination IP field and 0 in this field if you want to send
	all traffic to the gateway or interface specified in the Gateway IP or Interface field.
Gateway IP	Select the radio button and enter the IP address of the next-hop gateway. The gateway is
	a router or switch on the same segment as your ZyWALL's interface(s). The gateway
	helps forward packets to their destinations.
Interface	Select the radio button and a predefined interface through which the traffic is sent.
Metric	Metric represents the “cost” of transmission for routing purposes. IP routing uses hop
	count as the measurement of cost, with a minimum of 1 for directly connected networks.
	Enter a number that approximates the cost for this link. The number need not be precise,
	but it must be 0~127. In practice, 2 or 3 is usually a good number.
OK	Click OK to save your changes back to the ZyWALL.
Cancel	Click Cancel to exit this screen without saving.

9.4 Policy Routing Technical Reference

Here is more detailed information about some of the features you can configure in policy routing.

NAT and SNAT

NAT (Network Address Translation - NAT, RFC 1631) is the translation of the IP address in a packet in one network to a different IP address in another network. Use SNAT (Source NAT) to change the source IP address in one network to a different IP address in another network.

Assured Forwarding (AF) PHB for DiffServ

Assured Forwarding (AF) behavior is defined in RFC 2597. The AF behavior group defines four AF classes. Inside each class, packets are given a high, medium or low drop precedence. The drop precedence determines the probability that routers in the network will drop packets when congestion occurs. If congestion occurs between classes, the traffic in the higher class (smaller numbered class) is generally given priority. Combining the classes and drop precedence produces

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ZyWALL 110/310/1100 Series User’s Guide