Application Environment Of Static Routing; Configuring A Static Route; Configuration Prerequisites - 3Com MSR 50 Series Configuration Manual

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HAPTER TATIC
Application
Environment of Static
Routing
Configuring a Static
Route
Configuration
Prerequisites
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OUTING ONFIGURATION
Before configuring a static route, you need to know the following concepts:
1 Destination address and mask
In the ip route-static command, an IPv4 address is in dotted decimal format and
a mask can be either in dotted decimal format or in the form of mask length (the
digits of consecutive 1s in the mask).
2 Output interface and next hop address
While configuring a static route, you can specify either the output interface or the
next hop address depending on the specific occasion. The next hop address can
not be a local interface IP address; otherwise, the route configuration will not take
effect.
In fact, all the route entries must have a next hop address. When forwarding a
packet, a router first searches the routing table for the route to the destination
address of the packet. The system can find the corresponding link layer address
and forward the packet only after the next hop address is specified.
When specifying the output interface, note that:
If the output interface is a NULL0 or loopback interface, there is no need to
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configure the next hop address.
If the output interface is a point-to-point interface, there is no need to
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configure the next hop address. You need not change the configuration even if
the peer's address changes. For example, a PPP interface obtains the peer's IP
address through PPP negotiation, so you need only specify the output
interface.
If the output interface is an NBMA or P2MP interface, which support
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point-to-multipoint network, the IP address to link layer address mapping must
be established. Therefore, it is recommended to configure both the next hop IP
address and the output interface.
You are not recommended to specify a broadcast interface (such as an Ethernet
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interface, virtual template, or VLAN interface) as the output interface, because
a broadcast interface may have multiple next hops. If you have to do so, you
must specify the corresponding next hop for the output interface.
3 Other attributes
You can configure different preferences for different static routes so that route
management policies can be applied more flexibly. For example, specifying the
same preference for different routes to the same destination enables load sharing,
while specifying different preferences for these routes enables route backup.
Before configuring a static route, you need to finish the following tasks:
Configure the physical parameters for related interfaces
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