H3C Technologies H3C S12500 Series Switches - Manual (Page 284)

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The output shows that Switch C has established two BGP neighborships with Switch A.
# Display routes destined for 1.1.1.0/24 on Switch C.
display ip routing-table 1.1.1.0 24 verbose
Routing Table : Public
Summary Count : 2
Destination: 1.1.1.0/24
Protocol: BGP Process ID: 0
Preference: 0 Cost: 50
NextHop: 3.0.1.1 Interface: Vlan-interface101
BkNextHop: 0.0.0.0 BkInterface:
RelyNextHop: 3.0.2.1 Neighbor : 3.0.1.1
Tunnel ID: 0x0 Label: NULL
State: Active Adv Age: 00h08m54s
Tag: 0
Destination: 1.1.1.0/24
Protocol: BGP Process ID: 0
Preference: 0 Cost: 100
NextHop: 2.0.1.1 Interface: Vlan-interface201
BkNextHop: 0.0.0.0 BkInterface:
RelyNextHop: 2.0.2.1 Neighbor : 2.0.1.1
Tunnel ID: 0x0 Label: NULL
State: Invalid Adv Age: 00h08m54s
Tag: 0
The output shows that Switch A and Switch C communicate through Switch B, and Switch C has
two routes to reach network 1.1.1.0/24: Switch C<—>Switch B<—>Switch A, which is the active
route; Switch C<—>Switch D<—>Switch A, which is the backup route. Then the link Switch
C<—>Switch B<—>Switch A fails.
# Enable BFD debugging on Switch C.
debugging bfd scm
debugging bfd event
debugging bgp bfd
terminal monitor
terminal debugging
%Nov 5 11:42:24:172 2009 SwitchC BFD/5/BFD_CHANGE_FSM: Sess[3.0.2.2/3.0.1.1,
13/17,VLAN101,Ctrl], Sta: UP->DOWN, Diag: 1
%Nov 5 11:42:24:172 2009 SwitchC BGP/5/BGP_STATE_CHANGED: 3.0.1.1 state is changed
from ESTABLISHED to IDLE.
*Nov 5 11:42:24:187 2009 SwitchC RM/6/RMDEBUG: BGP_BFD: Recv BFD DOWN msg, Src IP
3.0.2.2, Dst IP 3.0.1.1, Instance ID 0.
*Nov 5 11:42:24:187 2009 SwitchC RM/6/RMDEBUG: BGP_BFD: Reset BGP session 3.0.1.1
for BFD session down.
*Nov 5 11:42:24:187 2009 SwitchC RM/6/RMDEBUG: BGP_BFD: Send DELETE msg to BFD,
Connection type DIRECT, Src IP 3.0.2.2, Dst IP 3.0.1.1, Instance ID 0.
The output shows that Switch C can quickly detect the link failure.
# Display routes destined for 1.1.1.0/24 on Switch C.
display ip routing-table 1.1.1.0 24 verbose