Configuring Default Routes In A Route Map Entry - HP ProCurve Secure Router 7203 dl Advanced Management And Configuration Manual

IP Routing—Configuring RIP, OSPF, BGP, and PBR
Configuring Policy-Based Routing
N o t e
13-138
The routing table for this router shown in Figure 13-31. When a routine packet
(IP precedence 0) destined to 192.168.66.12 arrives on the Ethernet interface,
the router looks up the entry for network 192.168.64.0 /20 in its routing table
and forwards the packet out PPP 2. The router uses the routing table entry
because the routine packet does not match the route map entry.
When a mission-critical packet (IP precedence 5) arrives, the router matches
the packet to the route map entry. It then routes the packet as indicated in the
route map entry. The router first attempts to route the high-priority traffic
through interface PPP 3 (the forwarding interface for 10.3.3.1). If this interface
were not available, or if the route to 10.3.3.1 did not exist, the router would
forward the traffic through PPP 1.
If the router cannot find a route for any of the addresses or interfaces specified
in the route map entry, it does not drop the packet. Instead, the router forwards
the packet according to the matching entry in its routing table. (If such an
entry does not exist, the router does drop the packet.)
If you want your router to drop packets that it cannot forward using a
manually-defined, traffic-specific route, you should enter a set command for
a null interface. For example:
ProCurve(config-route-map)# set ip next-hop 10.3.3.1
ProCurve(config-route-map)# set interface ppp 1 null 0
After trying to route packets to 10.3.3.1 and then through PPP 1, the router
drops them.

Configuring Default Routes in a Route Map Entry

You can use route maps to configure default routes that apply to only specific
types of traffic. Traffic-specific default routes are particularly useful when you
want to apply different policies to external traffic from different sources.
By definition, a routing table can only include one default route. Such a route
is usually used for all external traffic. However, your organization may want
to route some external traffic differently. For example, if your network
provides Internet access to guests, you might want to send such traffic to a
IDM device to screen it before allowing it to access the Internet connection.
You can add a default route that applies to most traffic in the routing table.
You can then configure a default route in a route map to override the global
default. The default route in the route map would only apply to a specific type
of traffic—for example, traffic from users that need additional screening.