H3C Technologies H3C S10500 Series Switches - Manual (Page 274)

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%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.
# Display route 1.1.1.0/24 on Switch C, and you can see that Switch A and Switch C communicate
through Switch D.
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: Vlan-interface201
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 output shows that Switch C has one route Switch C<—>Switch D<—>Switch A to reach network
1.1.1.0/24.
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.
2. Use the display bgp peer command to check that the peer’s IP address is correct.
3. If a loopback interface is used, check that the loopback interface is specified with the peer
connect-interface command.
4. If the peer is a non-direct eBGP peer, check that the peer ebgp-max-hop command is configured.
5. Check that a valid route to the peer is available.