3Com 4007, Руководство по внедрению, Страница: 492 / 684

492 C
HAPTER
19: O
PEN
S
HORTEST
P
ATH
F
IRST
(OSPF) R
OUTING
■
With the ability to wildcard policy parameters (such as 0.0.0.0 to
indicate all routers or all routes), occasions may arise when several
policies match a route. In such cases, routers use the following
procedure to determine which policy to apply to the route:
■
If multiple policies apply to the route, the router uses the policy
that has the highest administrative weight.
■
If multiple matches still exist, the router uses the policy that
matches the specified source (excluding wildcards).
■
If multiple matches still exist, the router compares route address
bits and uses the policy that best matches the route address
(excluding wildcards).
■
If multiple matches still exist, the router uses the policy that
matches the origin protocol.
■
If multiple matches still exist, then the router uses the policy that
has the lowest index number.
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You can set up an IP RIP or OSPF import or export policy to accept or
advertise the default route, as long as the default route exists in the
routing table. When you define a policy, you are always prompted for
the route subnet mask after the route address, even though you
specify the wildcard route address of 0.0.0.0.
Specify a route subnet mask as follows:
■
If you want the wildcard subnet mask for all routes, enter 0.0.0.0
for the subnet mask. This is the default subnet mask.
■
If you want the default route (not all routes), enter
255.255.255.255.
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For more information about IP routing policies, see Chapter 16.