Allied Telesis AT-9724TS specifications Route Preference Settings, Backup State IP address above

		Figure 6- 91. Static/Default Route Settings – Add window
The following fields can be set:
	Parameter	Description
	IP Address	Allows the entry of an IP address that will be a static entry into the Switch’s Routing Table.
	Subnet Mask	Allows the entry of a subnet mask corresponding to the IP address above.
	Gateway IP	Allows the entry of an IP address of a gateway for the IP address above.
	Metric (1-65535)	Allows the entry of a routing protocol metric representing the number of routers between the Switch and the
	Backup State	IP address above.
		The user may choose between Primary and Backup. If the Primary Static/Default Route fails, the Backup Route
		will support the entry. Please take note that the Primary and Backup entries cannot have the same Gateway.
Click Apply to implement changes made.

Route Preference Settings

Route Preference is a way for routers to select the best path when there are two or more different routes to the same destination from two different routing protocols.The majority of routing protocols are not compatible when used in conjunction with each other.This Switch supports and may be configured for many routing protocols, as a stand-alone switch or more importantly, in utilizing the stacking function and Single IP Management of the Switch.Therefore, the ability to exchange route information and select the best path is essential to optimal use of the Switch and its capabilities.

The first decision the Switch will make in selecting the best path is to consult the Route Preference Settings table of the switch.This table can be viewed by clicking Configuration > Layer 3 IP Networking > Route Preference Settings, and it holds the list of possible routing protocols currently implemented on the Switch, along with a Preference value which determines which routing protocol will be the most dependable to route packets. Below is a list of the default route preferences set on the Switch.

Route Type	Validity Range	Default Value
Local	0 – Permanently set on the switch and unconfigurable.	0
Static	1 – 999	60
OSPF Intra	1 – 999	80
OSPF Inter	1 – 999	90
RIP	1 – 999	100
OSPF ExtT1	1 – 999	110
OSPF ExtT2	1 – 999	115

Table 6- 8. Route Preference Table

As shown above, Local will always be the first choice for routing purposes and the next most reliable path is Static due to the fact that its has the next lowest value.To set a higher reliability for a route, change its value to a number less than the value of a route preference that has a greater reliability value using the New Route Preference Settings window command. For example, if the user wishes to make RIP the most reliable route, the user can change its value to one that is less than the lowest value (Static - 60) or the user could change the other route values to more than 100.

The user should be aware of three points before configuring the route preference:

1.No two route preference values can be the same. Entering the same route preference may cause the switch to crash due to indecision by the switch.

2.If the user is not fully aware of all the features and functions of the routing protocols on the switch, a change in the default route preference value may cause routing loops or black holes.

Allied Telesyn AT-9724TS High-Density Layer 3 Stackable Gigabit Ethernet Switch 98