BFD for BGP configuration
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Network Topology
Network requirements
As shown in Figure, configure OSPF as the IGP in AS 200.
· Establish two IBGP connections between Switch A and Switch C. When both paths operate correctly, Switch C uses the path Switch A<—>Switch B<—>Switch C to exchange packets with network 1.1.1.0/24.
· Configure BFD over the path. When the path fails, BFD can quickly detect the failure and notify it to BGP. Then, the path Switch A<—>Switch D<—>Switch C takes effect immediately.
|
Device |
interface |
IP |
Device |
interface |
IP |
|
Switch A |
Vlan-int100 |
3.0.1.1/24 |
Switch C |
Vlan-int101 |
3.0.2.2/24 |
|
|
Vlan-int200 |
2.0.1.1/24 |
|
Vlan-int201 |
2.0.2.2/24 |
|
|
Loopback0 |
1.1.1.1/24 |
|
Loopback0 |
5.5.5.5/24 |
|
Switch B |
Vlan-int100 |
3.0.1.2/24 |
Switch D |
Vlan-int200 |
2.0.1.2/24 |
|
|
Vlan-int101 |
3.0.2.1/24 |
|
Vlan-int201 |
2.0.2.1/24 |
Configuration Steps
Configuration procedure
1. Swithc A
#
ospf 1
area 0.0.0.0
network 2.0.1.0 0.0.0.255
network 3.0.1.0 0.0.0.255
#
acl number 2000
rule 0 permit source 1.1.1.0 0.0.0.255
#
route-policy apply_med_100 permit node 10
if-match ip address acl 2000
apply cost 100
#
route-policy apply_med_50 permit node 10
if-match ip address acl 2000
apply cost 50
#
#
bgp 200
peer 2.0.2.2 as-number 200
peer 3.0.2.2 as-number 200
peer 3.0.2.2 bfd
#
address-family ipv4 unicast
network 1.1.1.0 255.255.255.0
peer 2.0.2.2 enable
peer 2.0.2.2 route-policy apply_med_100 export
peer 3.0.2.2 enable
peer 3.0.2.2 route-policy apply_med_50 export
#
2. Swithc C
#
ospf 1
area 0.0.0.0
network 2.0.2.0 0.0.0.255
network 3.0.2.0 0.0.0.255
#
acl number 2000
rule 0 permit source 5.5.5.0 0.0.0.255
#
route-policy apply_med_100 permit node 10
if-match ip address acl 2000
apply cost 100
#
route-policy apply_med_50 permit node 10
if-match ip address acl 2000
apply cost 50
#
bgp 200
peer 2.0.1.1 as-number 200
peer 3.0.1.1 as-number 200
peer 3.0.1.1 bfd
#
address-family ipv4 unicast
network 5.5.5.0 255.255.255.0
peer 2.0.1.1 enable
peer 2.0.1.1 route-policy apply_med_100 export
peer 3.0.1.1 enable
peer 3.0.1.1 route-policy apply_med_50 export
#
3. Swithc B
#
ospf 1
area 0.0.0.0
network 3.0.1.0 0.0.0.255
network 3.0.2.0 0.0.0.255
#
ip route-static 1.1.1.0 24 3.0.1.1
ip route-static 5.5.5.0 24 3.0.2.2
#
4. Swithc D
#
ospf 1
area 0.0.0.0
network 2.0.1.0 0.0.0.255
network 2.0.2.0 0.0.0.255
#
ip route-static 1.1.1.0 24 2.0.1.1
ip route-static 5.5.5.0 24 2.0.2.2
#
Verifying the configuration
1. # Display detailed BFD session information on Switch C.
[SwitchC]dis bfd session verbose
Total Session Num: 1 Up Session Num: 1 Init Mode: Active
IPv4 session working in control packet mode:
Local Discr: 129 Remote Discr: 129
Source IP: 3.0.2.2 Destination IP: 3.0.1.1
Session State: Up Interface: N/A
Min Tx Inter: 400ms Act Tx Inter: 400ms
Min Rx Inter: 400ms Detect Inter: 2000ms
Rx Count: 2 Tx Count: 6
Connect Type: Indirect Running Up for: 00:16:04
Hold Time: 1600ms Auth mode: None
Detect Mode: Async Slot: 1
Protocol: BGP
Version: 1
Diag Info: No Diagnostic
The output shows that a BFD session has been established between Switch A and Switch C
[SwitchC]dis bgp peer ipv4
BGP local router ID: 10.3.1.1
Local AS number: 200
Total number of peers: 2 Peers in established state: 2
* - Dynamically created peer
^ - Peer created through link-local address
Peer AS MsgRcvd MsgSent OutQ PrefRcv Up/Down State
2.0.1.1 200 101 101 0 1 01:21:30 Established
3.0.1.1 200 11 11 0 1 00:06:39 Established
The output shows that Switch C has established two BGP connections with Switch A, and both connections are in Established state
[SwitchC]ping -a 5.5.5.5 1.1.1.1
Ping 1.1.1.1 (1.1.1.1) from 5.5.5.5: 56 data bytes, press CTRL+C to break
56 bytes from 1.1.1.1: icmp_seq=0 ttl=254 time=2.180 ms
56 bytes from 1.1.1.1: icmp_seq=1 ttl=254 time=6.879 ms
56 bytes from 1.1.1.1: icmp_seq=2 ttl=254 time=1.904 ms
56 bytes from 1.1.1.1: icmp_seq=3 ttl=254 time=1.900 ms
56 bytes from 1.1.1.1: icmp_seq=4 ttl=254 time=1.904 ms
2. # Display route 1.1.1.0/24 on Switch C.
[SwitchC]dis ip routing-table 1.1.1.1 verbose
Summary count : 1
Destination: 1.1.1.0/24
Protocol: BGP instance default
Process ID: 0
SubProtID: 0x1 Age: 00h17m30s
Cost: 50 Preference: 255
IpPre: N/A QosLocalID: N/A
Tag: 0 State: Active Adv
OrigTblID: 0x0 OrigVrf: default-vrf
TableID: 0x2 OrigAs: 0
NibID: 0x16000001 LastAs: 0
AttrID: 0x1 Neighbor: 3.0.1.1
Flags: 0x10060 OrigNextHop: 3.0.1.1
Label: NULL RealNextHop: 3.0.2.1
BkLabel: NULL BkNextHop: N/A
SRLabel: NULL BkSRLabel: NULL
SIDIndex: NULL InLabel: NULL
Tunnel ID: Invalid Interface: Vlan-interface101
BkTunnel ID: Invalid BkInterface: N/A
FtnIndex: 0x0 TrafficIndex: N/A
Connector: N/A PathID: 0x0
LinkCost: 0 MicroSegID: 0
The output shows that Switch C communicates with network 1.1.1.0/24 through the path Switch C<—>Switch B<—>Switch A.
3. # Break down the path Switch C<—>Switch B<—>Switch A and then display route 1.1.1.0/24 on Switch C.
[Swtich B]interface Ten-GigabitEthernet1/0/1
[Swtich B-Ten-GigabitEthernet1/0/1]shutdown
[SwitchC]dis ip routing-table 1.1.1.1 verbose
Summary count : 1
Destination: 1.1.1.0/24
Protocol: BGP instance default
Process ID: 0
SubProtID: 0x1 Age: 00h00m49s
Cost: 100 Preference: 255
IpPre: N/A QosLocalID: N/A
Tag: 0 State: Active Adv
OrigTblID: 0x0 OrigVrf: default-vrf
TableID: 0x2 OrigAs: 0
NibID: 0x16000002 LastAs: 0
AttrID: 0x2 Neighbor: 2.0.1.1
Flags: 0x10060 OrigNextHop: 2.0.1.1
Label: NULL RealNextHop: 2.0.2.1
BkLabel: NULL BkNextHop: N/A
SRLabel: NULL BkSRLabel: NULL
SIDIndex: NULL InLabel: NULL
Tunnel ID: Invalid Interface: Vlan-interface201
BkTunnel ID: Invalid BkInterface: N/A
FtnIndex: 0x0 TrafficIndex: N/A
Connector: N/A PathID: 0x0
LinkCost: 0 MicroSegID: 0
The output shows that Switch C communicates with network 1.1.1.0/24 through the path Switch C<—>Switch D<—>Switch A.