H3C Technologies H3C SR8800 - Manual (Page 279)

263
<RouterC> debugging bfd event
<RouterC> debugging bgp bfd
<RouterC> terminal monitor
<RouterC> terminal debugging
# The following debugging information shows that: when the link between Router A and Router B
fails, Router C can quickly detect the link failure.
%Nov 5 11:42:24:172 2009 RouterC BFD/5/BFD_CHANGE_FSM: Sess[3.0.2.2/3.0.1.1,13/17,
GigabitEthernet3/1/1,Ctrl], Sta: UP->DOWN, Diag: 1
%Nov 5 11:42:24:172 2009 RouterC BGP/5/BGP_STATE_CHANGED: 3.0.1.1 state is changed
from ESTABLISHED to IDLE.
*Nov 5 11:42:24:187 2009 RouterC 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 RouterC RM/6/RMDEBUG: BGP_BFD: Reset BGP session 3.0.1.1
for BFD session down.
*Nov 5 11:42:24:187 2009 RouterC 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 Router C, and you can see that Router A and Router C
communicate through Router D.
<RouterC> 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
Preference: 0 Cost: 100
NextHop: 2.0.1.1 Interface: GigabitEthernet3/1/2
BkNextHop: 0.0.0.0 BkInterface:
RelyNextHop: 2.0.2.1 Neighbor : 2.0.1.1
Tunnel ID: 0x0 Label: NULL
State: Active Adv Age: 00h09m54s
Tag: 0
The above output shows that Router C has one route to reach network 1.1.1.0/24, that is, Router
C<—>Router D<—>Router A.
Troubleshooting BGP
BGP peer relationship not established
Symptom
Display BGP peer information by using the display bgp peer command. The state of the connection to a
peer cannot become established.
Analysis
To become BGP peers, any two routers must establish a TCP session using port 179 and exchange Open
messages successfully.
Solution
1. Use the display current-configuration command to check that the peer’s AS number is correct.