3Com Switch 4200G Configuration Guide

402 CHAPTER 47: STATIC ROUTE CONFIGURATION
Static Route
Configuration
Static Route Configuration includes:
■ Configuring a static route
■ Configuring a default route
■ Deleting all the static routes
Configuring a static
route
Perform the following configurations in system view.
The parameters are explained as follows:
■ IP address and mask
The IP address and mask are in a dotted decimal format. As “1”s in the 32-bit
mask is required to be consecutive, the dotted decimal mask can also be replaced
by the mask-length (which refers to the digits of the consecutive “1”s in the
mask).
■ Next hop address and NULL interface
When configuring a static route, you can specify the next-hop to decide the next
hop address. In fact, for all the routing items, the next hop address must be
specified. When IP layer transmits a packet, it will first search the matching route
in the routing table according to 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 according to this
address.
You cannot specify an interface address of the local switch as the next hop address
of an static route.
The packets sent to NULL interface, a kind of virtual interface, will be discarded at
once. This can decrease the system load.
■ Preference
For different configurations of preference-value, you can flexibly apply the routing
management policy. For configuration of multiple routes to the destination, if you
specify the same precedence, load sharing is achieved. If not, the routing backup
takes place achieved.
■ Other parameters
The attributes reject and blackhole respectively indicate the unreachable route
and the blackhole route.
Table 344 Configuring a static route
Operation Command
Add a static route ip route-static ip-address { mask | mask-length } { interface-type
interface-number | next-hop } [ preference value ] [ reject |
blackhole ]
Delete a static route undo ip route-static ip-address { mask | mask-length } [
interface-type interface-number | next-hop ] [ preference value ] [
reject blackhole ]