Tuesday, January 16, 2018

BFD task #1.

Topology:




Configure loopback0 interfaces and links between routers according to topology diagram.
All routers are IOS.

Requirements: 

1. Configure all interfaces on all routers in OSPF area 0. Use Broadcast network type on all  ethernet     interfaces, and point-to-point on loopback interfaces. 
2. All traffic shall be forwarded via VLANs 10 and 20 when possible, and use VLANs 30 and 40 as       backup. Do not use interface "bandwidth" command. 
3. Configure the routers, such that Hosts on VLANs 30 and 40 cannot send any packets with spoofed     source address. 
4. Configure the network for sub-second convergence without changing the default OSPF timers. 
5. On routers R1 and R2, use a single command to enable BFD on all OSPF interfaces. 

Solution:

Highlight the text below to reveal the solution.

This task requires understanding of BFD configuration for IGP,  and  understanding BFD echo and no echo modes.

Requirement #1 and #2: configure OSPF on all interfaces, increase the OSPF cost on interfaces R2-R4 and R1-R5 to make this path less preferable compared to other links.

Requirement #3 - configure uRPF on routers R2, R4, R1, and R5, facing the VLANs 30 and 40.
Requirement #4 - disable "BFD echo" mode on VLAN 30 and VLAN 40 interfaces, to allow BFD to work along the uRPF configuration.

R1: 


!
interface Loopback0
 ip address 24.0.1.1 255.255.255.255
 ip ospf network point-to-point
 ip ospf 1 area 0
!
interface Ethernet0/0
 ip address 24.0.10.1 255.255.255.0
 ip ospf 1 area 0
 bfd interval 250 min_rx 250 multiplier 3
!
interface Ethernet0/1
 ip address 24.0.40.1 255.255.255.0
 ip verify unicast source reachable-via rx
 ip ospf 1 area 0
 ip ospf cost 100
 bfd interval 250 min_rx 250 multiplier 3
 no bfd echo
!
!
router ospf 1
 router-id 24.0.1.1
 bfd all-interfaces
!


R2:


!
interface Loopback0
 ip address 24.0.2.2 255.255.255.255
 ip ospf network point-to-point
 ip ospf 1 area 0
!
interface Ethernet0/0
 ip address 24.0.10.2 255.255.255.0
 ip ospf 1 area 0
 bfd interval 250 min_rx 250 multiplier 3
!
interface Ethernet0/1
 ip address 24.0.30.2 255.255.255.0
 ip verify unicast source reachable-via rx
 ip ospf 1 area 0
 ip ospf cost 100
 bfd interval 250 min_rx 250 multiplier 3
 no bfd echo
!
!
router ospf 1
 bfd all-interfaces
!

R3: 


!
interface Loopback0
 ip address 24.0.3.3 255.255.255.255
 ip ospf network point-to-point
 ip ospf 1 area 0
!
interface Ethernet0/0
 ip address 24.0.10.3 255.255.255.0
 ip ospf bfd
 ip ospf 1 area 0
 bfd interval 250 min_rx 250 multiplier 3
!
interface Ethernet0/1
 ip address 24.0.20.3 255.255.255.0
 ip ospf bfd
 ip ospf 1 area 0
 bfd interval 250 min_rx 250 multiplier 3
!
!
router ospf 1
 router-id 24.0.3.3
!


R4:


!
interface Loopback0
 ip address 24.0.4.4 255.255.255.255
 ip ospf network point-to-point
 ip ospf 1 area 0
!
interface Ethernet0/0
 ip address 24.0.20.4 255.255.255.0
 ip ospf bfd
 ip ospf 1 area 0
 bfd interval 250 min_rx 250 multiplier 3
!
interface Ethernet0/1
 ip address 24.0.30.4 255.255.255.0
 ip verify unicast source reachable-via rx
 ip ospf bfd
 ip ospf 1 area 0
 ip ospf cost 100
 bfd interval 250 min_rx 250 multiplier 3
 no bfd echo
!
!
router ospf 1
 router-id 24.0.4.4
!

R5:


!
interface Loopback0
 ip address 24.0.5.5 255.255.255.255
 ip ospf network point-to-point
 ip ospf 1 area 0
!
interface Ethernet0/0
 ip address 24.0.20.5 255.255.255.0
 ip ospf bfd
 ip ospf 1 area 0
 bfd interval 250 min_rx 250 multiplier 3
!
interface Ethernet0/1
 ip address 24.0.40.5 255.255.255.0
 ip verify unicast source reachable-via rx
 ip ospf bfd
 ip ospf 1 area 0
 ip ospf cost 100
 bfd interval 250 min_rx 250 multiplier 3
 no bfd echo
!
!
router ospf 1
 router-id 24.0.5.5
!

Verification:


R1#             show bfd neighbors

IPv4 Sessions
NeighAddr                              LD/RD         RH/RS     State     Int
24.0.10.2                               1/2          Up        Up        Et0/0
24.0.10.3                               8/8          Up        Up        Et0/0
24.0.40.5                               6/6          Up        Up        Et0/1


R1#sho ip ospf neighbor  detail
 Neighbor 24.0.2.2, interface address 24.0.10.2
    In the area 0 via interface Ethernet0/0, BFD enabled
    Neighbor priority is 1, State is FULL, 6 state changes
    DR is 24.0.10.1 BDR is 24.0.10.2
    Options is 0x12 in Hello (E-bit, L-bit)
    Options is 0x52 in DBD (E-bit, L-bit, O-bit)
    LLS Options is 0x1 (LR)
    Dead timer due in 00:00:39
    Neighbor is up for 00:44:31
    Index 1/1, retransmission queue length 0, number of retransmission 0
    First 0x0(0)/0x0(0) Next 0x0(0)/0x0(0)
    Last retransmission scan length is 0, maximum is 0
    Last retransmission scan time is 0 msec, maximum is 0 msec
 Neighbor 24.0.3.3, interface address 24.0.10.3
    In the area 0 via interface Ethernet0/0, BFD enabled
    Neighbor priority is 1, State is FULL, 6 state changes
    DR is 24.0.10.1 BDR is 24.0.10.2
    Options is 0x12 in Hello (E-bit, L-bit)
    Options is 0x52 in DBD (E-bit, L-bit, O-bit)
    LLS Options is 0x1 (LR)
    Dead timer due in 00:00:30
    Neighbor is up for 00:14:20
    Index 2/2, retransmission queue length 0, number of retransmission 0
    First 0x0(0)/0x0(0) Next 0x0(0)/0x0(0)
    Last retransmission scan length is 0, maximum is 0
    Last retransmission scan time is 0 msec, maximum is 0 msec
 Neighbor 24.0.5.5, interface address 24.0.40.5
    In the area 0 via interface Ethernet0/1, BFD enabled
    Neighbor priority is 1, State is FULL, 6 state changes
    DR is 24.0.40.5 BDR is 24.0.40.1
    Options is 0x12 in Hello (E-bit, L-bit)
    Options is 0x52 in DBD (E-bit, L-bit, O-bit)
    LLS Options is 0x1 (LR)
    Dead timer due in 00:00:38
    Neighbor is up for 00:18:27
    Index 3/3, retransmission queue length 0, number of retransmission 1
    First 0x0(0)/0x0(0) Next 0x0(0)/0x0(0)
    Last retransmission scan length is 1, maximum is 1
    Last retransmission scan time is 0 msec, maximum is 0 msec

R1# sho bfd neighbors details

IPv4 Sessions
NeighAddr                              LD/RD         RH/RS     State     Int
24.0.10.2                               1/2          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: 1
Local Diag: 0, Demand mode: 0, Poll bit: 0
MinTxInt: 1000000, MinRxInt: 1000000, Multiplier: 3
Received MinRxInt: 1000000, Received Multiplier: 3
Holddown (hits): 0(0), Hello (hits): 1000(1549)
Rx Count: 1499, Rx Interval (ms) min/max/avg: 1/1006/877 last: 600 ms ago
Tx Count: 1550, Tx Interval (ms) min/max/avg: 1/1005/880 last: 383 ms ago
Elapsed time watermarks: 0 0 (last: 0)
Registered protocols: OSPF
Uptime: 00:21:54
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: 1000000    - Min rx interval: 1000000
             Min Echo interval: 250000

IPv4 Sessions
NeighAddr                              LD/RD         RH/RS     State     Int
24.0.10.3                               8/8          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: 1000000, MinRxInt: 1000000, Multiplier: 3
Received MinRxInt: 1000000, Received Multiplier: 3
Holddown (hits): 0(0), Hello (hits): 1000(1030)
Rx Count: 1032, Rx Interval (ms) min/max/avg: 1/1006/877 last: 566 ms ago
Tx Count: 1032, Tx Interval (ms) min/max/avg: 1/1004/877 last: 521 ms ago
Elapsed time watermarks: 0 0 (last: 0)
Registered protocols: OSPF
Uptime: 00:15:05
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.: 8
             Min tx interval: 1000000    - Min rx interval: 1000000
             Min Echo interval: 250000

IPv4 Sessions
NeighAddr                              LD/RD         RH/RS     State     Int
24.0.40.5                               6/6          Up        Up        Et0/1
Session state is UP and not using echo function.
Session Host: Software
OurAddr: 24.0.40.1
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): 525(0), Hello (hits): 250(5199)
Rx Count: 5183, Rx Interval (ms) min/max/avg: 16/260/223 last: 225 ms ago
Tx Count: 5201, Tx Interval (ms) min/max/avg: 1/257/221 last: 2 ms ago
Elapsed time watermarks: 0 0 (last: 0)
Registered protocols: OSPF
Uptime: 00:19:11
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.: 6
             Min tx interval: 250000     - Min rx interval: 250000
             Min Echo interval: 0

No comments:

Post a Comment