3Com CoreBuilder 3500, Руководство по внедрению

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384 C
HAPTER
14: O
PEN
S
HORTEST
P
ATH
F
IRST
(OSPF)
Dead Interval The dead interval determines how long neighbor routers wait for a Hello
packet before they determine that a neighbor is inactive. Each time that a
router receives a Hello packet from a neighbor, the router resets the dead
interval timer for that neighbor. The dead interval must be the same for
all routers on the network. The default value for the dead interval is
4 times the default value for the Hello interval — 40 seconds.
Password OSPF supports simple password authentication. You can set security
passwords for OSPF interfaces so that only routers that know the
password participate in OSPF exchanges. Therefore, configure routers in
the same area that want to participate in the routing domain with the
same password.
When you configure a password on a router interface, the interface
inserts the specified password in the OSPF header of every packet that it
transmits and receives only those OSPF packets that contain the same
password.
Simple password authentication prevents routers from inadvertently
joining the area and helps ensure that only trusted routers participate in
the routing domain.
By default, OSPF interfaces on your system do not have associated
passwords. When no password is assigned to an interface, OSPF
exchanges are not authenticated so that, although a password may exist
in an OSPF packet header, it is not examined when it is received.
Statistics You can display interface statistics for diagnostic and network debugging
purposes. Viewing the statistics for a particular interface can provide
valuable information, such as whether the router is overburdened, and
the number of Hello interval, dead interval, area ID, and password
mismatches that the interface has seen on the network. For a complete
listing of OSPF interface statistics, see the
ip ospf interface
statistics
command in the Command Reference Guide .