3Com Switch 7700 Configuration Manual page 100

92 C 5: IP R
HAPTER OUTING
P O
ROTOCOL PERATION
Configuring a Static Route
Perform the following configurations in system view.
Table 2 Configuring a Static Route
Operation
Add a static route
Delete a static route
The parameters are explained as follows:
IP address and mask
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The IP address and mask use a decimal format. Because the 1s in the 32-bit
mask must be consecutive, the dotted decimal mask can also be replaced by
the mask-length which refers to the digits of the consecutive 1s in the mask.
Transmitting interface or next hop address
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When you configure a static route, you can specify either the interface-type
port-number to designate a transmitting interface, or the gateway-address to
decide the next hop address, depending on the actual conditions.
You can specify the transmitting interfaces in the cases below:
For the interface that supports resolution from the network address to the link
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layer address (such as the Ethernet interface that supports ARP), when
ip-address and mask (or mask-length) specifies a host address, and this
destination address is in the directly connected network, the transmitting
interface can be specified.
For a P2P interface, the address of the next hop defines the transmitting
■
interface because the address of the opposite interface is the address of the
next hop of the route.
In fact, for all routing items, the next hop address must be specified. When the
IP layer transmits a packet, it first searches the matching route in the routing
table, depending on the destination address of the packet. Only when the next
hop address of the route is specified, can the link layer find the corresponding
link layer address, and then forward the packet.
For different configurations of preference-value, you can flexibly apply the
■
routing management policy.
The reject and blackhole attributes indicate the unreachable route and the
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blackhole route.
Configuring a Default Route
Perform the following configurations in system view.
Table 3 Configuring a Default Route
Operation
Configure a default route
Command
ip route-static ip-address {mask |
mask-length } { interface-name |
gateway-address } [ preference value ] [
reject | blackhole ]
undo ip route-static ip-address {mask |
mask-length } { interface-name |
gateway-address} [ preference value ]
Command
ip route-static 0.0.0.0 { 0.0.0.0 | 0 } {
interface-name | gateway-address } [
preference value ] [ reject | blackhole ]