Route preferences configuration – Dell POWEREDGE M1000E User Manual

Page 531

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Configuring Routing

529

Adding a Router Route

1. Open the Configured Routes

page.

2. Click Add.

The

Router Route Entry Configuration page displays, as Figure 9-38 shows.

3. Next to Route Type, use the drop-down box to add a Default route or a Static route.

Default — Enter the default gateway address in the Next Hop IP Address field. Figure 9-38 shows the

fields that display when the

Route Type value is Default.

Static — Enter values for Network Address, Subnet Mask, Next Hop IP Address, and Preference.

Figure 9-39 shows the fields that display when the

Route Type value is Static.

4. Click Apply Changes.

The new route is added, and you are returned to the Configured Routes page.

Displaying Configured Routes using the CLI Command

For information about the CLI command that performs this function, see the following chapter in the

CLI Reference Guide:

• IP Routing Commands

Route Preferences Configuration

Use the Router Route Preferences Configuration

page to configure the default preference for each

protocol (for example 60 for static routes). These values are arbitrary values that range from 1 to 255, and

are independent of route metrics. Most routing protocols use a route metric to determine the shortest

path known to the protocol, independent of any other protocol.
The best route to a destination is chosen by selecting the route with the lowest preference value. When

there are multiple routes to a destination, the preference values are used to determine the preferred

route. If there is still a tie, the route with the best route metric is chosen. To avoid problems with

mismatched metrics (i.e. RIP and OSPF metrics are not directly comparable), you must configure

different preference values for each of the protocols.

Static Reject Routes

A static reject route is a static route to discard the packets to a particular destination, thereby forcing a

black-hole routing behavior for a particular set of IP prefixes. Static reject routes can help prevent a

routing loop in the network if a default route is configured on a router. Static reject routes also help

protect against a DOS attack on a router with unwanted destination addresses.

NOTE: Static reject routes are not redistributed by OSPF or RIP.

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