Following is an example of the
show ip route command output for a speci?¬?c subnet that has multiple routes available in the
routing table. Example 4-9 shows three equal-cost paths to the 194.168.20.0 network.
Notice the three routing descriptor blocks. Each block is one available route. Also note the asterisk
(*) next to one of the block entries. The asterisk corresponds to the active route that is used for
new traf?¬?c. The term ???new traf?¬?c??? corresponds to a single packet or an entire ?¬‚ow to a destination,
depending on whether the router is performing per-destination or per-packet load balancing.
OSPF Authentication
OSPF neighbor authentication (also called neighbor router authentication or route authentication)
can be con?¬?gured such that routers can participate in routing based on prede?¬?ned passwords.
When you con?¬?gure neighbor authentication on a router, the router authenticates the source of
each routing update packet that it receives. This authentication is accomplished by the exchange
of an authenticating key (sometimes referred to as a password) that is known to both the sending
and receiving router.
Types of Authentication
By default, OSPF uses null authentication (Type 0), which means that routing exchanges over a
network are not authenticated.
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