H3C S5800 Series Configuration Manual page 288

Summary Count : 2
Destination: 1.1.1.0/24
Protocol: BGP
Preference: 0
NextHop: 3.0.1.1
BkNextHop: 0.0.0.0
RelyNextHop: 3.0.2.1
Tunnel ID: 0x0
State: Active Adv
Tag: 0
Destination: 1.1.1.0/24
Protocol: BGP
Preference: 0
NextHop: 2.0.1.1
BkNextHop: 0.0.0.0
RelyNextHop: 2.0.2.1
Tunnel ID: 0x0
State: Invalid Adv
Tag: 0
The above output shows that Switch C has two routes to reach network 1.1.1.0/24: Switch
C<—>Switch B<—>Switch A, which is the currently active route; Switch C<—>Switch D<—>Switch A,
which is the backup route.
# Enable BFD debugging on Switch C.
<SwitchC> debugging bfd scm
<SwitchC> debugging bfd event
<SwitchC> debugging bgp bfd
<SwitchC> terminal monitor
<SwitchC> terminal debugging
# The following debugging information shows that: when the link between Switch A and Switch B fails,
Switch C can quickly detect the link failure.
%Nov 5 11:42:24:172
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.
# Display route 1.1.1.0/24 on Switch C, and you can see that Switch A and Switch C communicate
through Switch D.
<SwitchC> display ip routing-table 1.1.1.0 24 verbose
Routing Table : Public
Summary Count : 1
Destination: 1.1.1.0/24
Protocol: BGP
Process ID: 0
Cost: 50
Interface: Vlan-interface101
BkInterface:
Neighbor : 3.0.1.1
Label: NULL
Age: 00h08m54s
Process ID: 0
Cost: 100
Interface: Vlan-interface201
BkInterface:
Neighbor : 2.0.1.1
Label: NULL
Age: 00h08m54s
2009 SwitchC BFD/5/BFD_CHANGE_FSM:
Process ID: 0
6-71
Sess[3.0.2.2/3.0.1.1,