User's Manual

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Chapter 78 Configuring the Routing
Management Modules
78.1 Overview
The static route is a special route and configured by the administrator manually; after a static route is set the
packets with a designated destination will be forwarded along the path that is designated by the administrator.
In those networks with simple networking structures, only the configuration of the static routes can realize
network interconnection. Properly setting and using static routes can improve the performance of networks
and guarantee the bandwidth for important network application.
The shortage of the static route is that it cannot automatically adapt to the change of the network topology.
When the network has trouble or the topology changes, the static routes are unreachable and the
network then interrupts. In this case, the network administrator has to change the settings of static routes
manually.
If the data packets that reach a designated network cannot find the corresponding items in the routing table in
a device, the device will then discard these data packets.
After a default route is configured on the current device, those data packets that have no corresponding
items in the routing table will not be discarded by the current device but forwarded to another device, which
will forward these data packets.
The default route is used only when a device has not found a matching entry in the routing table.
If the destination address of a packet does not match up any entry in the routing table, this packet will select
the default route.
If there is no default route and the destination of the packet is not in the routing table, this packet will be
discarded and an ICMPv6 packet will be sent back to the source terminal, reporting that the destination
address and the network are unreachable.
The default routes can be generated in two ways:
The first way is that the network administrator sets a static route to network 0::0/0. As to an incoming data
packet, if the current device cannot find the corresponding routing item in the routing table, it will forward
this packet to the designated next-hop port that is set in the static route.
The second way is that the default route is generated by the dynamic routing protocols. A device with strong
routing ability forwards the default route to other devices, and the other devices generate in their own routing
tables the default route that is oriented to the device with strong routing ability.