Topology:
Use configuration from BFD task #1 as initial configuration for this task.
Router R6 is added to the topology.
Requirements:
1. Configure link between routers R6 and R4.
2. Configure eBGP session between routers R4 and R6.
3. Configure full-mesh of iBGP sessions between routers in AS24. Use loopback0 addresses for iBGP peerings.
4. Configure all BGP sessions for sub-second convergence. Don't change BGP session timers.
5. When possible, reduce the load on routers CPU introduced by BFD, by only processing BFD packets every 20 seconds.
Solution:
Highlight the text below to reveal the solution.
This task requires understanding of BFD configuration for BGP, multihop BFD configuration, and BFD slow-timers.
Requirement #4 - use multihop-BFD to activate BFD for iBGP peerings. You will need to configure bfd-multihop template and bfd map, then configure the BGP peers for BFD.
Requiremetn #5 - configure BFD slow-timers with value of 20000 msec. This will reduce the rate of BFD control packets to every 20 seconds, instead of every 1 second, but only for BFD sessions in echo mode.
!
bfd slow-timers 20000
bfd map ipv4 24.0.0.0/16 24.0.0.0/16 MH
bfd-template multi-hop MH
interval min-tx 250 min-rx 250 multiplier 3
!
bfd slow-timers 20000
bfd map ipv4 24.0.0.0/16 24.0.0.0/16 MH
bfd-template multi-hop MH
interval min-tx 250 min-rx 250 multiplier 3
!
!
interface Ethernet0/0
ip address 24.0.46.6 255.255.255.0
bfd interval 250 min_rx 250 multiplier 3
!
This task requires understanding of BFD configuration for BGP, multihop BFD configuration, and BFD slow-timers.
Requirement #4 - use multihop-BFD to activate BFD for iBGP peerings. You will need to configure bfd-multihop template and bfd map, then configure the BGP peers for BFD.
Requiremetn #5 - configure BFD slow-timers with value of 20000 msec. This will reduce the rate of BFD control packets to every 20 seconds, instead of every 1 second, but only for BFD sessions in echo mode.
R1, R2, R3, & R5:
!
bfd slow-timers 20000
bfd map ipv4 24.0.0.0/16 24.0.0.0/16 MH
bfd-template multi-hop MH
interval min-tx 250 min-rx 250 multiplier 3
!
!
router bgp 24
bgp log-neighbor-changes
neighbor IBGP peer-group
neighbor IBGP remote-as 24
neighbor IBGP update-source Loopback0
neighbor IBGP fall-over bfd
..
..
!
R4:
bfd slow-timers 20000
bfd map ipv4 24.0.0.0/16 24.0.0.0/16 MH
bfd-template multi-hop MH
interval min-tx 250 min-rx 250 multiplier 3
!
!
interface Ethernet1/0
ip address 24.0.46.4 255.255.255.0
bfd interval 250 min_rx 250 multiplier 3
!
!
router bgp 24
bgp log-neighbor-changes
neighbor IBGP peer-group
neighbor IBGP remote-as 24
neighbor IBGP update-source Loopback0
neighbor IBGP fall-over bfd
neighbor 24.0.1.1 peer-group IBGP
neighbor 24.0.2.2 peer-group IBGP
neighbor 24.0.3.3 peer-group IBGP
neighbor 24.0.5.5 peer-group IBGP
neighbor 24.0.46.6 remote-as 6
neighbor 24.0.46.6 fall-over bfd
!
R6:
!
interface Ethernet0/0
ip address 24.0.46.6 255.255.255.0
bfd interval 250 min_rx 250 multiplier 3
!
!
router bgp 6
bgp log-neighbor-changes
neighbor 24.0.46.4 remote-as 24
neighbor 24.0.46.4 fall-over bfd
!
Verification:
R1# show bfd neighbors
IPv4 Sessions
NeighAddr LD/RD RH/RS State Int
24.0.10.2 3/3 Up Up Et0/0
24.0.10.3 2/2 Up Up Et0/0
24.0.40.5 1/2 Up Up Et0/1
IPv4 Multihop Sessions
NeighAddr[vrf] LD/RD RH/RS State
24.0.2.2 4/5 Up Up
24.0.3.3 5/6 Up Up
24.0.4.4 9/5 Up Up
24.0.5.5 8/9 Up Up
R1# show bfd neighbors details
IPv4 Sessions
NeighAddr LD/RD RH/RS State Int
24.0.10.2 3/3 Up Up Et0/0
Session state is UP and using echo function with 250 ms interval.
Session Host: Software
OurAddr: 24.0.10.1
Handle: 3
Local Diag: 0, Demand mode: 0, Poll bit: 0
MinTxInt: 20000000, MinRxInt: 20000000, Multiplier: 3
Received MinRxInt: 20000000, Received Multiplier: 3
Holddown (hits): 0(0), Hello (hits): 20000(8609)
Rx Count: 8613, Rx Interval (ms) min/max/avg: 1/19954/1677 last: 3448 ms ago
Tx Count: 8614, Tx Interval (ms) min/max/avg: 1/19983/1661 last: 17741 ms ago
Elapsed time watermarks: 0 0 (last: 0)
Registered protocols: OSPF
Uptime: 02:20:18
Last packet: Version: 1 - Diagnostic: 0
State bit: Up - Demand bit: 0
Poll bit: 0 - Final bit: 0
C bit: 0
Multiplier: 3 - Length: 24
My Discr.: 3 - Your Discr.: 3
Min tx interval: 20000000 - Min rx interval: 20000000
Min Echo interval: 250000
IPv4 Sessions
NeighAddr LD/RD RH/RS State Int
24.0.10.3 2/2 Up Up Et0/0
Session state is UP and using echo function with 250 ms interval.
Session Host: Software
OurAddr: 24.0.10.1
Handle: 2
Local Diag: 0, Demand mode: 0, Poll bit: 0
MinTxInt: 20000000, MinRxInt: 20000000, Multiplier: 3
Received MinRxInt: 20000000, Received Multiplier: 3
Holddown (hits): 0(0), Hello (hits): 20000(8611)
Rx Count: 8629, Rx Interval (ms) min/max/avg: 1/20002/1676 last: 321 ms ago
Tx Count: 8616, Tx Interval (ms) min/max/avg: 1/19924/1665 last: 13155 ms ago
Elapsed time watermarks: 0 0 (last: 0)
Registered protocols: OSPF
Uptime: 02:20:21
Last packet: Version: 1 - Diagnostic: 0
State bit: Up - Demand bit: 0
Poll bit: 0 - Final bit: 0
C bit: 0
Multiplier: 3 - Length: 24
My Discr.: 2 - Your Discr.: 2
Min tx interval: 20000000 - Min rx interval: 20000000
Min Echo interval: 250000
IPv4 Sessions
NeighAddr LD/RD RH/RS State Int
24.0.40.5 1/2 Up Up Et0/1
Session state is UP and not using echo function.
Session Host: Software
OurAddr: 24.0.40.1
Handle: 1
Local Diag: 0, Demand mode: 0, Poll bit: 0
MinTxInt: 250000, MinRxInt: 250000, Multiplier: 3
Received MinRxInt: 250000, Received Multiplier: 3
Holddown (hits): 718(0), Hello (hits): 250(37946)
Rx Count: 37960, Rx Interval (ms) min/max/avg: 24/281/221 last: 33 ms ago
Tx Count: 37948, Tx Interval (ms) min/max/avg: 1/294/221 last: 15 ms ago
Elapsed time watermarks: 0 0 (last: 0)
Registered protocols: OSPF
Uptime: 02:20:21
Last packet: Version: 1 - Diagnostic: 0
State bit: Up - Demand bit: 0
Poll bit: 0 - Final bit: 0
C bit: 0
Multiplier: 3 - Length: 24
My Discr.: 2 - Your Discr.: 1
Min tx interval: 250000 - Min rx interval: 250000
Min Echo interval: 0
IPv4 Multihop Sessions
NeighAddr[vrf] LD/RD RH/RS State
24.0.2.2 4/5 Up Up
Session state is UP and not using echo function.
Session Host: Software
OurAddr: 24.0.1.1
Handle: 5
Local Diag: 0, Demand mode: 0, Poll bit: 0
MinTxInt: 250000, MinRxInt: 250000, Multiplier: 3
Received MinRxInt: 250000, Received Multiplier: 3
Holddown (hits): 548(0), Hello (hits): 250(11709)
Rx Count: 4233, Rx Interval (ms) min/max/avg: 1/271/222 last: 202 ms ago
Tx Count: 4227, Tx Interval (ms) min/max/avg: 1/258/221 last: 105 ms ago
Elapsed time watermarks: 0 0 (last: 0)
Registered protocols: BGP
Map information:
Destination[vrf]: 24.0.0.0/16
Source[vrf]: 24.0.0.0/16
Template: MH
Authentication(Type/Keychain): invalid_type/
Uptime: 00:15:37
Last packet: Version: 1 - Diagnostic: 0
State bit: Up - Demand bit: 0
Poll bit: 0 - Final bit: 0
C bit: 0
Multiplier: 3 - Length: 24
My Discr.: 5 - Your Discr.: 4
Min tx interval: 250000 - Min rx interval: 250000
Min Echo interval: 0
IPv4 Multihop Sessions
NeighAddr[vrf] LD/RD RH/RS State
24.0.3.3 5/6 Up Up
Session state is UP and not using echo function.
Session Host: Software
OurAddr: 24.0.1.1
Handle: 4
Local Diag: 0, Demand mode: 0, Poll bit: 0
MinTxInt: 250000, MinRxInt: 250000, Multiplier: 3
Received MinRxInt: 250000, Received Multiplier: 3
Holddown (hits): 680(0), Hello (hits): 250(11679)
Rx Count: 4179, Rx Interval (ms) min/max/avg: 1/258/222 last: 70 ms ago
Tx Count: 4180, Tx Interval (ms) min/max/avg: 1/267/222 last: 220 ms ago
Elapsed time watermarks: 0 0 (last: 0)
Registered protocols: BGP
Map information:
Destination[vrf]: 24.0.0.0/16
Source[vrf]: 24.0.0.0/16
Template: MH
Authentication(Type/Keychain): invalid_type/
Uptime: 00:15:27
Last packet: Version: 1 - Diagnostic: 0
State bit: Up - Demand bit: 0
Poll bit: 0 - Final bit: 0
C bit: 0
Multiplier: 3 - Length: 24
My Discr.: 6 - Your Discr.: 5
Min tx interval: 250000 - Min rx interval: 250000
Min Echo interval: 0
IPv4 Multihop Sessions
NeighAddr[vrf] LD/RD RH/RS State
24.0.4.4 9/5 Up Up
Session state is UP and not using echo function.
Session Host: Software
OurAddr: 24.0.1.1
Handle: 6
Local Diag: 0, Demand mode: 0, Poll bit: 0
MinTxInt: 250000, MinRxInt: 250000, Multiplier: 3
Received MinRxInt: 250000, Received Multiplier: 3
Holddown (hits): 681(0), Hello (hits): 250(4444)
Rx Count: 4154, Rx Interval (ms) min/max/avg: 16/260/222 last: 69 ms ago
Tx Count: 4149, Tx Interval (ms) min/max/avg: 2/258/222 last: 100 ms ago
Elapsed time watermarks: 0 0 (last: 0)
Registered protocols: BGP
Map information:
Destination[vrf]: 24.0.0.0/16
Source[vrf]: 24.0.0.0/16
Template: MH
Authentication(Type/Keychain): invalid_type/
Uptime: 00:15:20
Last packet: Version: 1 - Diagnostic: 0
State bit: Up - Demand bit: 0
Poll bit: 0 - Final bit: 0
C bit: 0
Multiplier: 3 - Length: 24
My Discr.: 5 - Your Discr.: 9
Min tx interval: 250000 - Min rx interval: 250000
Min Echo interval: 0
IPv4 Multihop Sessions
NeighAddr[vrf] LD/RD RH/RS State
24.0.5.5 8/9 Up Up
Session state is UP and not using echo function.
Session Host: Software
OurAddr: 24.0.1.1
Handle: 7
Local Diag: 0, Demand mode: 0, Poll bit: 0
MinTxInt: 250000, MinRxInt: 250000, Multiplier: 3
Received MinRxInt: 250000, Received Multiplier: 3
Holddown (hits): 693(0), Hello (hits): 250(5825)
Rx Count: 5821, Rx Interval (ms) min/max/avg: 1/267/222 last: 57 ms ago
Tx Count: 5828, Tx Interval (ms) min/max/avg: 1/257/221 last: 192 ms ago
Elapsed time watermarks: 0 0 (last: 0)
Registered protocols: BGP
Map information:
Destination[vrf]: 24.0.0.0/16
Source[vrf]: 24.0.0.0/16
Template: MH
Authentication(Type/Keychain): invalid_type/
Uptime: 00:21:31
Last packet: Version: 1 - Diagnostic: 0
State bit: Up - Demand bit: 0
Poll bit: 0 - Final bit: 0
C bit: 0
Multiplier: 3 - Length: 24
My Discr.: 9 - Your Discr.: 8
Min tx interval: 250000 - Min rx interval: 250000
Min Echo interval: 0
R4# show bfd neighbors
IPv4 Sessions
NeighAddr LD/RD RH/RS State Int
24.0.20.3 2/5 Up Up Et0/0
24.0.20.5 1/12 Up Up Et0/0
24.0.30.2 3/4 Up Up Et0/1
24.0.46.6 4/1 Up Up Et1/0
IPv4 Multihop Sessions
NeighAddr[vrf] LD/RD RH/RS State
24.0.1.1 5/9 Up Up
24.0.2.2 6/7 Up Up
24.0.3.3 7/8 Up Up
24.0.5.5 8/13 Up Up
R4#sho
R4#show bf
R4#show bfd nei
R4#show bfd neighbors deta
R4#show bfd neighbors details
IPv4 Sessions
NeighAddr LD/RD RH/RS State Int
24.0.20.3 2/5 Up Up Et0/0
Session state is UP and using echo function with 250 ms interval.
Session Host: Software
OurAddr: 24.0.20.4
Handle: 2
Local Diag: 0, Demand mode: 0, Poll bit: 0
MinTxInt: 20000000, MinRxInt: 20000000, Multiplier: 3
Received MinRxInt: 20000000, Received Multiplier: 3
Holddown (hits): 0(0), Hello (hits): 20000(214)
Rx Count: 221, Rx Interval (ms) min/max/avg: 1/19993/5860 last: 9513 ms ago
Tx Count: 218, Tx Interval (ms) min/max/avg: 1/19861/5915 last: 15078 ms ago
Elapsed time watermarks: 0 0 (last: 0)
Registered protocols: OSPF
Uptime: 00:21:38
Last packet: Version: 1 - Diagnostic: 0
State bit: Up - Demand bit: 0
Poll bit: 0 - Final bit: 0
C bit: 0
Multiplier: 3 - Length: 24
My Discr.: 5 - Your Discr.: 2
Min tx interval: 20000000 - Min rx interval: 20000000
Min Echo interval: 250000
IPv4 Sessions
NeighAddr LD/RD RH/RS State Int
24.0.20.5 1/12 Up Up Et0/0
Session state is UP and using echo function with 250 ms interval.
Session Host: Software
OurAddr: 24.0.20.4
Handle: 1
Local Diag: 0, Demand mode: 0, Poll bit: 0
MinTxInt: 20000000, MinRxInt: 20000000, Multiplier: 3
Received MinRxInt: 20000000, Received Multiplier: 3
Holddown (hits): 0(0), Hello (hits): 20000(217)
Rx Count: 223, Rx Interval (ms) min/max/avg: 1/20007/5797 last: 15649 ms ago
Tx Count: 222, Tx Interval (ms) min/max/avg: 1/19984/5883 last: 2565 ms ago
Elapsed time watermarks: 0 0 (last: 0)
Registered protocols: OSPF
Uptime: 00:21:42
Last packet: Version: 1 - Diagnostic: 0
State bit: Up - Demand bit: 0
Poll bit: 0 - Final bit: 0
C bit: 0
Multiplier: 3 - Length: 24
My Discr.: 12 - Your Discr.: 1
Min tx interval: 20000000 - Min rx interval: 20000000
Min Echo interval: 250000
IPv4 Sessions
NeighAddr LD/RD RH/RS State Int
24.0.30.2 3/4 Up Up Et0/1
Session state is UP and not using echo function.
Session Host: Software
OurAddr: 24.0.30.4
Handle: 7
Local Diag: 0, Demand mode: 0, Poll bit: 0
MinTxInt: 250000, MinRxInt: 250000, Multiplier: 3
Received MinRxInt: 250000, Received Multiplier: 3
Holddown (hits): 577(0), Hello (hits): 250(5844)
Rx Count: 5839, Rx Interval (ms) min/max/avg: 2/258/222 last: 173 ms ago
Tx Count: 5847, Tx Interval (ms) min/max/avg: 1/261/221 last: 65 ms ago
Elapsed time watermarks: 0 0 (last: 0)
Registered protocols: OSPF
Uptime: 00:21:33
Last packet: Version: 1 - Diagnostic: 0
State bit: Up - Demand bit: 0
Poll bit: 0 - Final bit: 0
C bit: 0
Multiplier: 3 - Length: 24
My Discr.: 4 - Your Discr.: 3
Min tx interval: 250000 - Min rx interval: 250000
Min Echo interval: 0
IPv4 Sessions
NeighAddr LD/RD RH/RS State Int
24.0.46.6 4/1 Up Up Et1/0
Session state is UP and using echo function with 250 ms interval.
Session Host: Software
OurAddr: 24.0.46.4
Handle: 8
Local Diag: 0, Demand mode: 0, Poll bit: 0
MinTxInt: 20000000, MinRxInt: 20000000, Multiplier: 3
Received MinRxInt: 20000000, Received Multiplier: 3
Holddown (hits): 0(0), Hello (hits): 20000(64)
Rx Count: 66, Rx Interval (ms) min/max/avg: 1/19989/17146 last: 15620 ms ago
Tx Count: 65, Tx Interval (ms) min/max/avg: 15130/19968/17532 last: 8095 ms ago
Elapsed time watermarks: 0 0 (last: 0)
Registered protocols: BGP
Uptime: 00:18:50
Last packet: Version: 1 - Diagnostic: 0
State bit: Up - Demand bit: 0
Poll bit: 0 - Final bit: 0
C bit: 0
Multiplier: 3 - Length: 24
My Discr.: 1 - Your Discr.: 4
Min tx interval: 20000000 - Min rx interval: 20000000
Min Echo interval: 250000
IPv4 Multihop Sessions
NeighAddr[vrf] LD/RD RH/RS State
24.0.1.1 5/9 Up Up
Session state is UP and not using echo function.
Session Host: Software
OurAddr: 24.0.4.4
Handle: 6
Local Diag: 0, Demand mode: 0, Poll bit: 0
MinTxInt: 250000, MinRxInt: 250000, Multiplier: 3
Received MinRxInt: 250000, Received Multiplier: 3
Holddown (hits): 671(0), Hello (hits): 250(4683)
Rx Count: 4679, Rx Interval (ms) min/max/avg: 1/259/222 last: 79 ms ago
Tx Count: 4686, Tx Interval (ms) min/max/avg: 11/260/221 last: 95 ms ago
Elapsed time watermarks: 0 0 (last: 0)
Registered protocols: BGP
Map information:
Destination[vrf]: 24.0.0.0/16
Source[vrf]: 24.0.0.0/16
Template: MH
Authentication(Type/Keychain): invalid_type/
Uptime: 00:17:18
Last packet: Version: 1 - Diagnostic: 0
State bit: Up - Demand bit: 0
Poll bit: 0 - Final bit: 0
C bit: 0
Multiplier: 3 - Length: 24
My Discr.: 9 - Your Discr.: 5
Min tx interval: 250000 - Min rx interval: 250000
Min Echo interval: 0
IPv4 Multihop Sessions
NeighAddr[vrf] LD/RD RH/RS State
24.0.2.2 6/7 Up Up
Session state is UP and not using echo function.
Session Host: Software
OurAddr: 24.0.4.4
Handle: 4
Local Diag: 0, Demand mode: 0, Poll bit: 0
MinTxInt: 250000, MinRxInt: 250000, Multiplier: 3
Received MinRxInt: 250000, Received Multiplier: 3
Holddown (hits): 572(0), Hello (hits): 250(4682)
Rx Count: 4676, Rx Interval (ms) min/max/avg: 1/262/222 last: 178 ms ago
Tx Count: 4685, Tx Interval (ms) min/max/avg: 5/258/222 last: 34 ms ago
Elapsed time watermarks: 0 0 (last: 0)
Registered protocols: BGP
Map information:
Destination[vrf]: 24.0.0.0/16
Source[vrf]: 24.0.0.0/16
Template: MH
Authentication(Type/Keychain): invalid_type/
Uptime: 00:17:18
Last packet: Version: 1 - Diagnostic: 0
State bit: Up - Demand bit: 0
Poll bit: 0 - Final bit: 0
C bit: 0
Multiplier: 3 - Length: 24
My Discr.: 7 - Your Discr.: 6
Min tx interval: 250000 - Min rx interval: 250000
Min Echo interval: 0
IPv4 Multihop Sessions
NeighAddr[vrf] LD/RD RH/RS State
24.0.3.3 7/8 Up Up
Session state is UP and not using echo function.
Session Host: Software
OurAddr: 24.0.4.4
Handle: 5
Local Diag: 0, Demand mode: 0, Poll bit: 0
MinTxInt: 250000, MinRxInt: 250000, Multiplier: 3
Received MinRxInt: 250000, Received Multiplier: 3
Holddown (hits): 696(0), Hello (hits): 250(4676)
Rx Count: 4681, Rx Interval (ms) min/max/avg: 1/259/221 last: 54 ms ago
Tx Count: 4679, Tx Interval (ms) min/max/avg: 3/258/222 last: 53 ms ago
Elapsed time watermarks: 0 0 (last: 0)
Registered protocols: BGP
Map information:
Destination[vrf]: 24.0.0.0/16
Source[vrf]: 24.0.0.0/16
Template: MH
Authentication(Type/Keychain): invalid_type/
Uptime: 00:17:18
Last packet: Version: 1 - Diagnostic: 0
State bit: Up - Demand bit: 0
Poll bit: 0 - Final bit: 0
C bit: 0
Multiplier: 3 - Length: 24
My Discr.: 8 - Your Discr.: 7
Min tx interval: 250000 - Min rx interval: 250000
Min Echo interval: 0
IPv4 Multihop Sessions
NeighAddr[vrf] LD/RD RH/RS State
24.0.5.5 8/13 Up Up
Session state is UP and not using echo function.
Session Host: Software
OurAddr: 24.0.4.4
Handle: 3
Local Diag: 0, Demand mode: 0, Poll bit: 0
MinTxInt: 250000, MinRxInt: 250000, Multiplier: 3
Received MinRxInt: 250000, Received Multiplier: 3
Holddown (hits): 601(0), Hello (hits): 250(4682)
Rx Count: 4678, Rx Interval (ms) min/max/avg: 1/283/222 last: 149 ms ago
Tx Count: 4685, Tx Interval (ms) min/max/avg: 7/257/222 last: 104 ms ago
Elapsed time watermarks: 0 0 (last: 0)
Registered protocols: BGP
Map information:
Destination[vrf]: 24.0.0.0/16
Source[vrf]: 24.0.0.0/16
Template: MH
Authentication(Type/Keychain): invalid_type/
Uptime: 00:17:18
Last packet: Version: 1 - Diagnostic: 0
State bit: Up - Demand bit: 0
Poll bit: 0 - Final bit: 0
C bit: 0
Multiplier: 3 - Length: 24
My Discr.: 13 - Your Discr.: 8
Min tx interval: 250000 - Min rx interval: 250000
Min Echo interval: 0
