3Com 4500G Family Configuration Manual page 336

A local routing table store
the router will deliver to the FIB table to guide p
is based on the preferences of routing protoc
C ont nts of a routing table e
A ro uting table includes the following key items:
Destination address: Destination IP address or destination network.
Network mask: Specifies, in company with the destination address, the address of the destination
network. A logical AND operation between the destination address and the network mask yields
the address of the destination network. For example, if the destination address is 129.102.8.10 a
the mask 255.255.0.0, the address of the destination network is 129.102.0.0. A network mask is
made of a certain number of consecutive 1s. It can be expressed in dotted decimal format or by the
number of the 1s.
Outbound interface: Specifies the interface through which the IP packets are to be forwarded.
IP address of the next hop: Specifies the address of the next router on the path. If only the
outbound interface is configured, its address will be the IP address
Priority for the route. Routes to the same destinatio
different priorities and be found by various r
route is the one with the highest priority
Routes can be divided into two categories by destination:
Subnet routes: The destination is a subnet.
Host routes: The destination is a host.
Based on whether the destination is directly connected to a given router, routes can be divided into:
Direct routes: The destination is directly connected to the router.
Indirect routes: The destination is not directly connected to the router.
To prevent the routing table from getting too large, you can configure a default route. All packets without
matching any entry in the routing table will be forwa
In Figure 1-1 , the IP address on each cloud represents the address of the network. Router G is
connected to three networks and therefore has three IP addresses for its three physical interfaces. Its
routing table is shown under the network topology.
s the routes found by all protocols and determines the optimal routes that
acket forwarding. The selection of an optimal route
ols and metrics of routes.
outing protocols or manually configured. The optimal
(with the smallest metric).
rded through the default route.
1-2
of the next hop.
n but having different nexthops may have
nd