Enable BFD strict-mode for an OSPF interface so that the OSPF neighbor remains down until the BFD session is up.
Strict-mode is a BFD operation mode in OSPF where a neighbor remains down until the BFD session is up. When strict-mode is active, the neighbor state can display as awaiting BFD session up in the show ospf neighbor command output.
Strict-mode and non-strict-mode are incompatible. Both BFD neighbors must run IOS XR images that support strict-mode and must use strict-mode to form an adjacency.
Use this task to configure BFD strict-mode for OSPF on an interface and verify that the OSPF interface reports strict-mode operation.
Before you begin
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Ensure at least one IP address is configured on the router (OSPF routing requires at least one active IP address).
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Identify the OSPF process number, area IDs, and interfaces for OSPF participation.
Follow these steps to configure and verify OSPF areas and neighbours:
Procedure
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1. |
Enter global configuration mode.
Example:
Router# configure
Router(config)# router ospf 0
Router(config-ospf)# area 0
Router(config-ospf-ar)# interface GigabitEthernet0/3/0/1
Router(config-ospf-ar-if)# bfd fast-detect strict-mode
Router(config-ospf-ar-if)# commit
Router(config-ospf-ar-if)# end
Router# show ospf interface GigabitEthernet0/3/0/1
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2. |
Verify the OSPF interface information.
Example:
Router# show ospf interface gigabitEthernet 0/3/0/1
GigabitEthernet0/3/0/1 is up, line protocol is up
Internet Address 10.1.1.2/24, Area 0
Process ID 1, Router ID 10.2.2.2, Network Type BROADCAST, Cost: 1
Transmit Delay is 1 sec, State DR, Priority 1, MTU 1500, MaxPktSz 1500
BFD enabled, BFD interval 150 msec, BFD multiplier 3, Mode: Strict
Designated Router (ID) 10.2.2.2, Interface address 10.1.1.2
No backup designated router on this network
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
Hello due in 00:00:07:358
Index 1/1, flood queue length 0
Next 0(0)/0(0)
Last flood scan length is 1, maximum is 1
Last flood scan time is 0 msec, maximum is 0 msec
LS Ack List: current length 0, high water mark 1
Neighbor Count is 1, Adjacent neighbor count is 0
Suppress hello for 0 neighbor(s)
Multi-area interface Count is 0
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3. |
Verify the output of the show ospf neighbor command. # in the output indicates that the neighbor is waiting for the BFD session to come up.
Example:
Router# show ospf neighbor
Neighbors for OSPF 1
Neighbor ID Pri State Dead Time Address Interface
10.1.1.1 0 DOWN/DROTHER 00:00:33 10.1.1.3/24 GigabitEthernet0/3/0/1#
Total neighbor count: 1
When BFD strict-mode is enabled, the value of Mode displays as Strict. By default, the value of Mode displays as Default.
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BFD strict-mode is enabled for the OSPF interface.