Route Failover - D-Link DFL-1600 User Manual

10.4. Route Failover

After the database of each router is fully exchanged and synchronized,
the router will calculate a Shortest Path First(SPF) tree to all known
destinations based on the database. By running the SPF algorithm,
each router will be able to determine the best(least-cost) path for
data forwarding to any destination in the area. The destination,
associated cost, and the next hop to reach the destination will be
appended into each router's IP routing table.
Upon any update to the link-state database, a router will recalculate
the shortest path tree and update the routing table.
OSPF Authentication
Authentication is available as an optional securing method for the
OSPF environment. A router can validate the identity of another
router during the link-state information exchange. OSPF
authentication an be either none, simple, or MD5. With simple
authentication, the passphrase goes in clear-text over the link, while
with MD5 message-digest algorithm, the key will not pass over the
link directly. Thus, MD5 should be considered as a more secure
authentication mode. More information about encryption, message
digest, and authentication can be found in
Cryptography.
10.4 Route Failover
The route failover feature can be used when there is two or more routes to
a destination. For instance in a scenario where two ISP:s are available to
connect to the Internet. One ISP, the primary, is used in the normal case,
and a backup ISP is used when the primary ISP is down.
Routes can be monitored in two ways. A monitored route can be
considered down if link status on the interface is down, or if the default
gateway doesn't answer on ARP requests. It is possible to use both
monitoring methods at the same time.
D-Link Firewalls User's Guide
20.2 Introduction to
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