Edge-Core ECS4660-28F, Руководство по управлению, Страница: 1801 / 2020

C
HAPTER
51
| IP Routing Commands
Open Shortest Path First (OSPFv3)
– 1801 –
Area Configuration
area stub
This command defines a stub area. To remove a stub, use the no form
without the optional keyword. To remove the summary attribute, use the
no form with the summary keyword.
S
YNTAX
[ no ] area area-id stub [ no-summary ]
area-id - Identifies the stub area. The area ID can be in the form of
an IPv4 address or as a four octet unsigned integer ranging from
0-4294967295.
no-summary - Stops an Area Border Router (ABR) from sending
summary link advertisements into the stub area.
C
OMMAND
M
ODE
Router Configuration
D
EFAULT
S
ETTING
No stub is configured.
Summary advertisement are sent into the stub.
C
OMMAND
U
SAGE
◆
All routers in a stub must be configured with the same area ID.
◆
Routing table space is saved by stopping an ABR from flooding Type-4
Inter-Area Router and Type 5 AS-External LSAs into the stub. Since no
information on external routes is known inside the stub, an ABR will
advertise the default route 0::0/0 using a Type 3 Inter-Area Prefix LSA.
◆
The default setting for this command blocks Type-4 Inter-Area Router
and Type 5 AS-External LSAs. Therefore, any destinations that cannot
be matched to an inter-area or intra-area route will have to use the
default route.
◆
Use the no-summary parameter of this command on an ABR attached
to the stub to define a totally stubby area, blocking all Type 3 network
summary LSAs. Define an area as a totally stubby area only if routers
in the area do not require summary LSAs from other areas.
◆
Use the area default-cost command to specify the cost of a default
summary route sent into a stub by an ABR attached to the stub area.
E
XAMPLE
This example creates a stub area 2, and makes it totally stubby by blocking
all Type 3 summary LSAs.
Console(config-router)#area 2 stub no-summary
Console(config-router)#