HP 600 Series, Services And Applications

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To achieve this effect, router C will be configured to advertise its ISDN route
to D as lower in cost than the individual ISDN static routes from A and B to
D. (Note that this ISDN route from C to D would be configured to be more
costly than the WAN route when the WAN route to D is up.) The following
table shows an example of how to configure the above solution for access to
10.4.8.
x with and without a break in the WAN route to router D.
Route Type Internet Address
(Destination)
Next Hop Router Condition Cost to
Destination
Primary
10.1.8.
x
11.1.8.1 (A) n/a 1
10.2.8.
x
11.1.8.2 (B)
10.3.8. x 11.1.8.3 (C)
Conditional
Static
10.1.8. x 12.1.8.3 (C) Use if
11.1.8.4 (WAN)
goes down
3
10.2.8. x
10.3.8. x
Static Only
10.1.8. x 12.1.8.1 (A) n/a 5
10.2.8. x 12.1.8.2 (B) n/a 5
10.3.8. x 12.1.8.3 (C) n/a 3
Preference and the Routing Pool
The IP router maintains a routing pool which contains information supplied
by up to three routing protocols (RIP, EGP, OSPF) in addition to statically
configured routes. Consequently, the routing pool may contain multiple
routes to the same destination. Each route carries an associated preference
value that determines the “best” route where more than one is available. The
forwarding table is constructed with this best route for each known destina-
tion. The routing pool is updated in response to received protocol traffic;
updates are subsequently reflected in the forwarding table. The pool also
provides the database used by the routing protocols to prepare their link
state/routing advertisements. You can mediate the flow of routing data to
and from the routing pool; see “Routing Filters”, the next section after
“Static Routing”.
Internet Protocol Routing Service
Static Routing
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