BFD Static Route Configuration
This chapter describes the configurations for BFD static routes.
In order to establish alternate paths to destinations that have the least possible delay it is important to quickly detect any changes to static route validity. BFD detects the liveliness of a static route’s nexthop and then uses the nexthop’s reachability information to determine whether routes are valid. Using BFD to reach a static route’s nexthop also ensures that a static route is inserted in the forwarding database only when the nexthop neighbor is reachable.
Topology
BFD Static Route Basic Topology
R1
R1(config)#interface eth2 | Enter the Interface configuration mode for eth2. |
R1(config-if)#ip address 10.1.1.1/24 | Assign IP address on interface. |
R1(config-if)#commit | Commit the candidate configuration to the running configuration. |
R1(config-if)#exit | Exit the Interface configuration mode. |
R2
R2#configure terminal | Enter the Configure mode. |
R2(config)#ip route 30.1.1.0/24 20.1.1.3 | Configure static route. |
R2(config)#ip bfd static all-interfaces | Enable BFD for all static routes. |
R2(config)#interface eth1 | Enter the Interface configuration mode for eth1. |
R2(config-if)#ip static bfd enable | Enable static BFD on the interface. |
R2(config-if)#ip address 20.1.1.2/24 | Assign IP address on interface. |
R2(config-if)#commit | Commit the candidate configuration to the running configuration. |
R2(config-if)#exit | Exit the Interface configuration mode. |
R2(config)# ip static 30.1.1.0/24 20.1.1.3 fall-over-bfd enable | Enable static BFD at static route level. |
R2(config)#interface eth2 | Enter the Interface configuration mode for eth2. |
R2(config-if)#ip address 10.1.1.2/24 | Assign IP address on interface. |
R2(config-if)#commit | Commit the candidate configuration to the running configuration. |
R2(config-if)#exit | Exit the Interface configuration mode. |
R3
R3#configure terminal | Enter the Configure mode. |
R3(config)#ip route 10.1.1.0/24 20.1.1.2 | Configure static route. |
R3(config)#ip bfd static all-interfaces | Enable BFD for all static routes. |
R3(config)#interface eth1 | Enter the Interface configuration mode for eth1. |
R3(config-if)#ip address 20.1.1.3/24 | Assign IP address on interface. |
R3(config-if)#ip static bfd enable | Enable static BFD at interface level. |
R3(config-if)#commit | Commit the candidate configuration to the running configuration. |
R3(config-if)#exit | Exit the Interface configuration mode. |
R3(config)#ip static 10.1.1.0/24 20.1.1.2 fall-over-bfd enable | Enable static BFD at static route level. |
R3(config)#interface eth2 | Enter the Interface configuration mode for eth2. |
R3(config-if)#ip address 30.1.1.2/24 | Assign IP address on interface. |
R3(config-if)#commit | Commit the candidate configuration to the running configuration. |
R3(config-if)#exit | Exit the Interface configuration mode. |
R4
R4(config)#interface eth2 | Enter the Interface configuration mode for eth2. |
R4(config-if)#ip address 30.1.1.1/24 | Assign IP address on interface. |
R4(config-if)#commit | Commit the candidate configuration to the running configuration. |
R4(config-if)#exit | Exit the Interface configuration mode. |
Validation
R2
#sh bfd session
Sess-Idx Remote-Disc Lower-Layer Sess-Type Sess-State UP-Time Remote-Addr
5 1 IPv4 Single-Hop Up 00:09:32 20.1.1.3/32
Number of Sessions: 1
VPC2#sh bfd session detail
======================================================
Session Interface Index : 3 Session Index : 5
Lower Layer : IPv4 Version : 1
Session Type : Single Hop Session State : Up
Local Discriminator : 5 Local Address : 20.1.1.2/32
Remote Discriminator : 1 Remote Address : 20.1.1.3/32
Local Port : 49156 Remote Port : 3784
Options :
Diagnostics : None
Timers in Milliseconds :
Min Tx: 250 Min Rx: 250 Multiplier: 3
Neg Tx: 250 Neg Rx: 2000 Neg detect mult: 3
Min echo Tx: 1000 Min echo Rx: 1000 Neg echo intrvl: 0
Storage type : 2
Sess down time : 00:00:00
Sess discontinue time : 00:00:00
Bfd GTSM Disabled
Bfd Authentication Disabled
Counters values:
Pkt In : 0000000000000a29 Pkt Out : 0000000000000bb6
Echo Out : 0000000000000000 IPv6 Echo Out : 0000000000000000
IPv6 Pkt In : 0000000000000000 IPv6 Pkt Out : 0000000000000000
UP Count : 1 UPTIME : 00:09:34
Protocol Client Info:
RIB-> Client ID: 42 Flags: 4
----------------------------------------------------------
Number of Sessions: 1
R3
#sh bfd session
Sess-Idx Remote-Disc Lower-Layer Sess-Type Sess-State UP-Time Remote-Addr
1 5 IPv4 Single-Hop Up 00:09:39 20.1.1.2/32
Number of Sessions: 1
VPC3#sh bfd session detail
======================================================
Session Interface Index : 3 Session Index : 1
Lower Layer : IPv4 Version : 1
Session Type : Single Hop Session State : Up
Local Discriminator : 1 Local Address : 20.1.1.3/32
Remote Discriminator : 5 Remote Address : 20.1.1.2/32
Local Port : 49152 Remote Port : 3784
Options :
Diagnostics : None
Timers in Milliseconds :
Min Tx: 250 Min Rx: 250 Multiplier: 3
Neg Tx: 250 Neg Rx: 250 Neg detect mult: 3
Min echo Tx: 1000 Min echo Rx: 1000 Neg echo intrvl: 0
Storage type : 2
Sess down time : 00:00:00
Sess discontinue time : 00:00:00
Bfd GTSM Disabled
Bfd Authentication Disabled
Counters values:
Pkt In : 0000000000000a59 Pkt Out : 0000000000000a53
Echo Out : 0000000000000000 IPv6 Echo Out : 0000000000000000
IPv6 Pkt In : 0000000000000000 IPv6 Pkt Out : 0000000000000000
UP Count : 1 UPTIME : 00:09:41
Protocol Client Info:
RIB-> Client ID: 42 Flags: 4
----------------------------------------------------------
Number of Sessions: 1