3Com Switch 4800G PWR 24-Port, Руководство по настройке

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1-2
Figure 1-1 A sample routing table
Switch A
Switch B
Switch H
Switch E
16.0.0.2
17.0.0.3
15.0.0.0
12.0.0.0
17.0.0.0
11.0.0.0 16.0.0.0
13.0.0.0
14.0.0.0
Switch C
Switch D
Switch F
Switch G
11.0.0.1
12.0.0.1
12.0.0.2
15.0.0.1
15.0.0.2
17.0.0.1
16.0.0.1
13.0.0.1
13.0.0.2
14.0.0.1
14.0.0.2
14.0.0.3
14.0.0.4
17.0.0.2
11.0.0.2
13.0.0.3
Destination Network Nexthop Interface
11.0.0.0 11.0.0.1 2
12.0.0.0 12.0.0.1 1
13.0.0.0 12.0.0.2 1
14.0.0.0 14.0.0.4 3
15.0.0.0 14.0.0.2 3
16.0.0.0 14.0.0.2 3
17.0.0.0 11.0.0.2 2
Static Route
A static route is a manually configured. If a network’s topology is simple, you only need to configure
static routes for the network to work normally. The proper configuration and usage of static routes can
improve network performance and ensure bandwidth for important network applications.
The disadvantage of using static routes is that they cannot adapt to network topology changes. If a fault
or a topological change occurs in the network, the routes will be unreachable and the network breaks. In
this case, the network administrator has to modify the static routes manually.
Default Route
If the destination address of a packet fails to match any entry in the routing table, the packet will be
discarded.
After a default route is configured on a switch, any packet whose destination IP address matches no
entry in the routing table can be forwarded to a designated upstream switch.
A switch selects the default route only when it cannot find any matching entry in the routing table.
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If the destination address of a packet fails to match any entry in the routing table, the switch selects
the default route to forward the packet.