Friday, 13 July 2012

IS-IS: Basic Configuration

IS-IS: Basic Configuration
               
IS-IS:
·         IS-IS is an Interior Gateway Protocol (IGP) developed in the 1980s as the Routing Protocol for Open System Interconnection; RFC 1142.
·         When IS-IS is used to support IP, it is called Integrated IS-IS (RFC 1195)

·         IS-IS is also a link-state protocol like OSPF and runs SPF Algorithm to find the best routes.
·         There is no Area-0 in IS-IS, But Backbone area (level-2) is a set of L1/L2 and L2 routers and has to be contiguous
·         In OSPF, each link belongs to an Area, but in IS-IS each Router belongs to an Area.

·         Integrated IS-IS still requires OSI address, called a “Connection-Less Network Services”, CLNS address.
·         NSAP Address:
o    NSAP Address varies from 8 to 20 octets and it has three parts.
·         Area Address: Area is like an IP Subnet, describing a group or location
·         System ID: ID identifies a particular member in that location, like the host portion of IP address
·         NSEL: Similar to a TCP port, identifies the process on the host.
o    Ex: 49.0001.1111.1111.1111.00
·         All Cisco routers have NSEL 00
·         System-ID is always 6 bytes length
·         In the OSI, 49 represent Private address.
·         The NET address is a NSAP address of the Host, with the NSEL set to 00

·         In IS-IS terminology, a router is called Intermediate System (IS)
·         Intermediate Systems can be in 3 Levels of Routing Hierarchy.
o    L1, Level1: Which is responsible for intra-area routing
o    L1/L2, Level-1-2: Responsible for intra-area and inter-area routing
o    L2, Level-2: Inter-area only

Let me take a small topology to configure IS-IS:


·         R1 & R2: Area1
·         R3 & R4: Area2
·         R5: Area3

Net Address:
·         R1: 49.0001.1111.1111.1111.00
·         R2: 49.0001.2222.2222.2222.00
·         R3: 49.0002.3333.3333.3333.00
·         R4: 49.0002.4444.4444.4444.00
·         R5: 49.0003.5555.5555.5555.00

Configuration:

R1(config-if)#router isis
R1(config-router)#net 49.0001.1111.1111.1111.00
R1(config-router)#is-type level-1
R1(config-router)#int ser1/0
R1(config-if)#ip router isis
R1#
R1#show clns neighbors

System Id      Interface   SNPA                State  Holdtime  Type Protocol
R2             Se1/0       *HDLC*              Up     27        L1   IS-IS
R1#

R2(config-if)#router isis
R2(config-router)#net 49.0001.2222.2222.2222.00
R2(config-router)#is-type level-1-2
R2(config-router)#int ser1/0
R2(config-if)#ip router isis
R2(config-if)#isis circuit-type level-1
R2(config-if)#int ser1/1
R2(config-if)#ip router isis
R2(config-if)#isis circuit-type level-2-only
R2(config-if)#
R2#show clns neighbors

System Id      Interface   SNPA                State  Holdtime  Type Protocol
R1             Se1/0       *HDLC*              Up     26        L1   IS-IS
R3             Se1/1       *HDLC*              Up     26        L2   IS-IS
R2#


R3(config-if)#router isis
R3(config-router)#net 49.0002.3333.3333.3333.00
R3(config-router)#is-type level-2-only
R3(config-router)#int ser1/1
R3(config-if)#ip router isis
R3(config-if)#int ser1/0
R3(config-if)#ip router isis
R3(config-if)#end
R3#
R3#show clns neighbors

System Id      Interface   SNPA                State  Holdtime  Type Protocol
R2             Se1/1       *HDLC*              Up     25        L2   IS-IS
R4             Se1/0       *HDLC*              Up     27        L2   IS-IS
R3#

R4(config-if)#router isis
R4(config-router)#net 49.0002.4444.4444.4444.00
R4(config-router)#is-type level-2-only
R4(config-router)#int ser1/0
R4(config-if)#ip router isis
R4(config-if)#int ser1/1
R4(config-if)#ip router isis
R4(config-if)#end
R4#show clns neighbors

System Id      Interface   SNPA                State  Holdtime  Type Protocol
R3             Se1/0       *HDLC*              Up     27        L2   IS-IS
R5             Se1/1       *HDLC*              Up     23        L2   IS-IS
R4#

R5(config-if)#router isis
R5(config-router)#net 49.0003.5555.5555.5555.00
R5(config-router)#is-type level-2-only
R5(config-router)#int ser1/1
R5(config-if)#ip router isis
R5(config-if)#end
R5#show clns neighbors

System Id      Interface   SNPA                State  Holdtime  Type Protocol
R4             Se1/1       *HDLC*              Up     20        L2   IS-IS
R5#

R1#show clns
Global CLNS Information:
  1 Interfaces Enabled for CLNS
  NET: 49.0001.1111.1111.1111.00
  Configuration Timer: 60, Default Holding Timer: 300, Packet Lifetime 64
  ERPDU's requested on locally generated packets
  Running IS-IS in IP-only mode (CLNS forwarding not allowed)
R1#

R2#show clns
Global CLNS Information:
  2 Interfaces Enabled for CLNS
  NET: 49.0001.2222.2222.2222.00
  Configuration Timer: 60, Default Holding Timer: 300, Packet Lifetime 64
  ERPDU's requested on locally generated packets
  Running IS-IS in IP-only mode (CLNS forwarding not allowed)
R2#

R3#show clns
Global CLNS Information:
  2 Interfaces Enabled for CLNS
  NET: 49.0002.3333.3333.3333.00
  Configuration Timer: 60, Default Holding Timer: 300, Packet Lifetime 64
  ERPDU's requested on locally generated packets
  Running IS-IS in IP-only mode (CLNS forwarding not allowed)
R3#

R4#show clns
Global CLNS Information:
  2 Interfaces Enabled for CLNS
  NET: 49.0002.4444.4444.4444.00
  Configuration Timer: 60, Default Holding Timer: 300, Packet Lifetime 64
  ERPDU's requested on locally generated packets
  Running IS-IS in IP-only mode (CLNS forwarding not allowed)
R4#

R5#show clns
Global CLNS Information:
  1 Interfaces Enabled for CLNS
  NET: 49.0003.5555.5555.5555.00
  Configuration Timer: 60, Default Holding Timer: 300, Packet Lifetime 64
  ERPDU's requested on locally generated packets
  Running IS-IS in IP-only mode (CLNS forwarding not allowed)
R5#

R1#show clns interface ser1/0
Serial1/0 is up, line protocol is up
  Checksums enabled, MTU 1500, Encapsulation HDLC
  ERPDUs enabled, min. interval 10 msec.
  CLNS fast switching enabled
  CLNS SSE switching disabled
  DEC compatibility mode OFF for this interface
  Next ESH/ISH in 28 seconds
  Routing Protocol: IS-IS
    Circuit Type: level-1-2
    Interface number 0x0, local circuit ID 0x100
    Neighbor System-ID: R2
    Level-1 Metric: 10, Priority: 64, Circuit ID: R2.00
    Level-1 IPv6 Metric: 10
    Number of active level-1 adjacencies: 1
    Next IS-IS Hello in 4 seconds
    if state UP
R1#

R2#show clns interface ser1/0
Serial1/0 is up, line protocol is up
  Checksums enabled, MTU 1500, Encapsulation HDLC
  ERPDUs enabled, min. interval 10 msec.
  CLNS fast switching enabled
  CLNS SSE switching disabled
  DEC compatibility mode OFF for this interface
  Next ESH/ISH in 12 seconds
  Routing Protocol: IS-IS
    Circuit Type: level-1
    Interface number 0x0, local circuit ID 0x100
    Neighbor System-ID: R1
    Level-1 Metric: 10, Priority: 64, Circuit ID: R2.00
    Level-1 IPv6 Metric: 10
    Number of active level-1 adjacencies: 1
    Next IS-IS Hello in 6 seconds
    if state UP
R2#
R2#show clns interface ser1/1
Serial1/1 is up, line protocol is up
  Checksums enabled, MTU 1500, Encapsulation HDLC
  ERPDUs enabled, min. interval 10 msec.
  CLNS fast switching enabled
  CLNS SSE switching disabled
  DEC compatibility mode OFF for this interface
  Next ESH/ISH in 3 seconds
  Routing Protocol: IS-IS
    Circuit Type: level-2
    Interface number 0x1, local circuit ID 0x101
    Neighbor System-ID: R3
    Level-2 Metric: 10, Priority: 64, Circuit ID: R2.01
    Level-2 IPv6 Metric: 10
    Number of active level-2 adjacencies: 1
    Next IS-IS Hello in 2 seconds
    if state UP
R2#

R3#show clns interface ser1/1
Serial1/1 is up, line protocol is up
  Checksums enabled, MTU 1500, Encapsulation HDLC
  ERPDUs enabled, min. interval 10 msec.
  CLNS fast switching enabled
  CLNS SSE switching disabled
  DEC compatibility mode OFF for this interface
  Next ESH/ISH in 32 seconds
  Routing Protocol: IS-IS
    Circuit Type: level-1-2
    Interface number 0x0, local circuit ID 0x100
    Neighbor System-ID: R2
    Level-2 Metric: 10, Priority: 64, Circuit ID: R3.00
    Level-2 IPv6 Metric: 10
    Number of active level-2 adjacencies: 1
    Next IS-IS Hello in 8 seconds
    if state UP
R3#
R3#show clns interface ser1/0
Serial1/0 is up, line protocol is up
  Checksums enabled, MTU 1500, Encapsulation HDLC
  ERPDUs enabled, min. interval 10 msec.
  CLNS fast switching enabled
  CLNS SSE switching disabled
  DEC compatibility mode OFF for this interface
  Next ESH/ISH in 18 seconds
  Routing Protocol: IS-IS
    Circuit Type: level-1-2
    Interface number 0x1, local circuit ID 0x101
    Neighbor System-ID: R4
    Level-2 Metric: 10, Priority: 64, Circuit ID: R3.01
    Level-2 IPv6 Metric: 10
    Number of active level-2 adjacencies: 1
    Next IS-IS Hello in 428 milliseconds
    if state UP
R3#

R4#show clns interface ser1/1
Serial1/1 is up, line protocol is up
  Checksums enabled, MTU 1500, Encapsulation HDLC
  ERPDUs enabled, min. interval 10 msec.
  CLNS fast switching enabled
  CLNS SSE switching disabled
  DEC compatibility mode OFF for this interface
  Next ESH/ISH in 37 seconds
  Routing Protocol: IS-IS
    Circuit Type: level-1-2
    Interface number 0x1, local circuit ID 0x101
    Neighbor System-ID: R5
    Level-2 Metric: 10, Priority: 64, Circuit ID: R4.01
    Level-2 IPv6 Metric: 10
    Number of active level-2 adjacencies: 1
    Next IS-IS Hello in 5 seconds
    if state UP
R4#
R4#show clns interface ser1/0
Serial1/0 is up, line protocol is up
  Checksums enabled, MTU 1500, Encapsulation HDLC
  ERPDUs enabled, min. interval 10 msec.
  CLNS fast switching enabled
  CLNS SSE switching disabled
  DEC compatibility mode OFF for this interface
  Next ESH/ISH in 22 seconds
  Routing Protocol: IS-IS
    Circuit Type: level-1-2
    Interface number 0x0, local circuit ID 0x100
    Neighbor System-ID: R3
    Level-2 Metric: 10, Priority: 64, Circuit ID: R4.00
    Level-2 IPv6 Metric: 10
    Number of active level-2 adjacencies: 1
    Next IS-IS Hello in 3 seconds
    if state UP
R4#

R5#show clns interface ser1/1
Serial1/1 is up, line protocol is up
  Checksums enabled, MTU 1500, Encapsulation HDLC
  ERPDUs enabled, min. interval 10 msec.
  CLNS fast switching enabled
  CLNS SSE switching disabled
  DEC compatibility mode OFF for this interface
  Next ESH/ISH in 33 seconds
  Routing Protocol: IS-IS
    Circuit Type: level-1-2
    Interface number 0x0, local circuit ID 0x100
    Neighbor System-ID: R4
    Level-2 Metric: 10, Priority: 64, Circuit ID: R5.00
    Level-2 IPv6 Metric: 10
    Number of active level-2 adjacencies: 1
    Next IS-IS Hello in 5 seconds
    if state UP
R5#

R1#show ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route

Gateway of last resort is 100.1.12.2 to network 0.0.0.0

     1.0.0.0/32 is subnetted, 1 subnets
C       1.1.1.1 is directly connected, Loopback0
     100.0.0.0/24 is subnetted, 1 subnets
C       100.1.12.0 is directly connected, Serial1/0
i*L1 0.0.0.0/0 [115/10] via 100.1.12.2, Serial1/0
R1#ping 100.1.45.5

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 100.1.45.5, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 124/138/156 ms
R1#

R2#show ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route

Gateway of last resort is not set

     2.0.0.0/32 is subnetted, 1 subnets
C       2.2.2.2 is directly connected, Loopback0
     100.0.0.0/24 is subnetted, 4 subnets
i L2    100.1.34.0 [115/20] via 100.1.23.3, Serial1/1
i L2    100.1.45.0 [115/30] via 100.1.23.3, Serial1/1
C       100.1.12.0 is directly connected, Serial1/0
C       100.1.23.0 is directly connected, Serial1/1
R2#

R3#show ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route

Gateway of last resort is not set

     100.0.0.0/24 is subnetted, 4 subnets
C       100.1.34.0 is directly connected, Serial1/0
i L2    100.1.45.0 [115/20] via 100.1.34.4, Serial1/0
i L2    100.1.12.0 [115/20] via 100.1.23.2, Serial1/1
C       100.1.23.0 is directly connected, Serial1/1
     3.0.0.0/32 is subnetted, 1 subnets
C       3.3.3.3 is directly connected, Loopback0
R3#


R4#show ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route

Gateway of last resort is not set

     100.0.0.0/24 is subnetted, 4 subnets
C       100.1.34.0 is directly connected, Serial1/0
C       100.1.45.0 is directly connected, Serial1/1
i L2    100.1.12.0 [115/30] via 100.1.34.3, Serial1/0
i L2    100.1.23.0 [115/20] via 100.1.34.3, Serial1/0
     4.0.0.0/32 is subnetted, 1 subnets
C       4.4.4.4 is directly connected, Loopback0
R4#

R5#show ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route

Gateway of last resort is not set

     100.0.0.0/24 is subnetted, 4 subnets
i L2    100.1.34.0 [115/20] via 100.1.45.4, Serial1/1
C       100.1.45.0 is directly connected, Serial1/1
i L2    100.1.12.0 [115/40] via 100.1.45.4, Serial1/1
i L2    100.1.23.0 [115/30] via 100.1.45.4, Serial1/1
     5.0.0.0/32 is subnetted, 1 subnets
C       5.5.5.5 is directly connected, Loopback0
R5#ping 100.1.12.1

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 100.1.12.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 88/120/152 ms
R5#



Sunday, 8 July 2012

OSPF: Virtual Links – Part III - Authentication

OSPF: Virtual Links – Part III - Authentication

·         In the previous 2 posts, OSPF: Virtual Links - Part I and OSPF: Virtual Links – Part II, we have learnt why Virtual-links, how to create virtual-links, what scenarios we need to create virtual links etc.

·         In this post, we will see how to configure OSPF authentication for Virtual Links.

·         As we know already, Virtual-links are part of Backbone Area.
·         So, whenever we have authentication in Area 0, we have to authenticate the Virtual-links also.

·         As per the RFC, OSPF must do authentication for all the links.
·         OSPF uses 3 types of authentication:
o    By default, OSPF does Type-0 authentication, or null authentication or no authentication.
o    Type-1 or clear-text authentication
o    Type-2 or MD5 authentication

·         We can enable OSPF authentication either under the OSPF process or under the interface
·         In both the cases, we have to configure the password under the interface.
·         For MD5 authentication, Password and the key-id must match.

·         In the below example, I’m going to configure MD5 authentication.

Topology:

R1#show run | begin router ospf 1
router ospf 1
 router-id 1.1.1.1
 log-adjacency-changes
 network 1.1.1.1 0.0.0.0 area 0
 network 100.1.12.1 0.0.0.0 area 0
!

R2#show run | begin router ospf 1
router ospf 1
 router-id 2.2.2.2
 log-adjacency-changes
 area 23 virtual-link 3.3.3.3
 network 2.2.2.2 0.0.0.0 area 0
 network 100.1.12.2 0.0.0.0 area 0
 network 100.1.23.2 0.0.0.0 area 23
!

R3#show run | begin router ospf 1
router ospf 1
 router-id 3.3.3.3
 log-adjacency-changes
 area 23 virtual-link 2.2.2.2
 network 3.3.3.3 0.0.0.0 area 23
 network 100.1.23.3 0.0.0.0 area 23
 network 100.1.34.3 0.0.0.0 area 34
!

R4#show run | begin router ospf 1

router-id 4.4.4.4
 log-adjacency-changes
 network 4.4.4.4 0.0.0.0 area 34
 network 100.1.34.4 0.0.0.0 area 34
!

R1#show ip route ospf
     2.0.0.0/32 is subnetted, 1 subnets
O       2.2.2.2 [110/65] via 100.1.12.2, 00:00:38, Serial1/0
     100.0.0.0/24 is subnetted, 3 subnets
O IA    100.1.34.0 [110/192] via 100.1.12.2, 00:00:38, Serial1/0
O IA    100.1.23.0 [110/128] via 100.1.12.2, 00:00:38, Serial1/0
     3.0.0.0/32 is subnetted, 1 subnets
O IA    3.3.3.3 [110/129] via 100.1.12.2, 00:00:38, Serial1/0
     4.0.0.0/32 is subnetted, 1 subnets
O IA    4.4.4.4 [110/193] via 100.1.12.2, 00:00:38, Serial1/0
R1#

R2#show ip route ospf
     1.0.0.0/32 is subnetted, 1 subnets
O       1.1.1.1 [110/65] via 100.1.12.1, 00:00:39, Serial1/0
     100.0.0.0/24 is subnetted, 3 subnets
O IA    100.1.34.0 [110/128] via 100.1.23.3, 00:00:39, Serial1/1
     3.0.0.0/32 is subnetted, 1 subnets
O       3.3.3.3 [110/65] via 100.1.23.3, 01:22:20, Serial1/1
     4.0.0.0/32 is subnetted, 1 subnets
O IA    4.4.4.4 [110/129] via 100.1.23.3, 00:00:39, Serial1/1
R2#

R3#show ip route ospf
     1.0.0.0/32 is subnetted, 1 subnets
O       1.1.1.1 [110/129] via 100.1.23.2, 00:32:59, Serial1/1
     2.0.0.0/32 is subnetted, 1 subnets
O       2.2.2.2 [110/65] via 100.1.23.2, 00:32:59, Serial1/1
     100.0.0.0/24 is subnetted, 3 subnets
O       100.1.12.0 [110/128] via 100.1.23.2, 00:32:59, Serial1/1
     4.0.0.0/32 is subnetted, 1 subnets
O       4.4.4.4 [110/65] via 100.1.34.4, 00:32:29, Serial1/0
R3#

R4#show ip route ospf
     1.0.0.0/32 is subnetted, 1 subnets
O IA    1.1.1.1 [110/193] via 100.1.34.3, 00:32:28, Serial1/0
     2.0.0.0/32 is subnetted, 1 subnets
O IA    2.2.2.2 [110/129] via 100.1.34.3, 00:32:28, Serial1/0
     100.0.0.0/24 is subnetted, 3 subnets
O IA    100.1.12.0 [110/192] via 100.1.34.3, 00:32:28, Serial1/0
O IA    100.1.23.0 [110/128] via 100.1.34.3, 00:32:28, Serial1/0
     3.0.0.0/32 is subnetted, 1 subnets
O IA    3.3.3.3 [110/65] via 100.1.34.3, 00:32:28, Serial1/0
R4#

Observation:

·         OSPF has been configured as per the topology
·         Virtual-link has been configured between R2 and R3 through Area-23

Configuring OSPF authentication in Area-0:

R1(config)#router ospf 1
R1(config-router)#area 0 authentication message-digest
R1(config-router)#

R1(config-router)#int ser1/0
R1(config-if)#ip ospf authentication message-digest
R1(config-if)#ip ospf message-digest-key 10 md5 cisco123
R1(config-if)#

R2(config)#router ospf 1
R2(config-router)#area 0 authentication message-digest
R2(config-router)#area 23 virtual-link 3.3.3.3 message-digest-key 10 md5 cisco123
R2(config-router)#

R2(config-router)#int ser1/0
R2(config-if)#ip ospf authentication message-digest
R2(config-if)#ip ospf message-digest-key 10 md5 cisco123
R2(config-if)#

R3(config)#router ospf 1
R3(config-router)#area 0 authentication message-digest
R3(config-router)#area 23 virtual-link 2.2.2.2 message-digest-key 10 md5 cisco123
R3(config-router)#

R1#show ip ospf interface ser1/0
Serial1/0 is up, line protocol is up
  Internet Address 100.1.12.1/24, Area 0
  Process ID 1, Router ID 1.1.1.1, Network Type POINT_TO_POINT, Cost: 64
  Transmit Delay is 1 sec, State POINT_TO_POINT,
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    oob-resync timeout 40
    Hello due in 00:00:02
  Supports Link-local Signaling (LLS)
  Index 2/2, flood queue length 0
  Next 0x0(0)/0x0(0)
  Last flood scan length is 1, maximum is 1
  Last flood scan time is 0 msec, maximum is 0 msec
  Neighbor Count is 1, Adjacent neighbor count is 1
    Adjacent with neighbor 2.2.2.2
  Suppress hello for 0 neighbor(s)
  Message digest authentication enabled
    Youngest key id is 10
R1#

R2#show ip ospf interface ser1/0
Serial1/0 is up, line protocol is up
  Internet Address 100.1.12.2/24, Area 0
  Process ID 1, Router ID 2.2.2.2, Network Type POINT_TO_POINT, Cost: 64
  Transmit Delay is 1 sec, State POINT_TO_POINT,
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    oob-resync timeout 40
    Hello due in 00:00:07
  Supports Link-local Signaling (LLS)
  Index 2/2, flood queue length 0
  Next 0x0(0)/0x0(0)
  Last flood scan length is 1, maximum is 4
  Last flood scan time is 0 msec, maximum is 4 msec
  Neighbor Count is 1, Adjacent neighbor count is 1
    Adjacent with neighbor 1.1.1.1
  Suppress hello for 0 neighbor(s)
  Message digest authentication enabled
    Youngest key id is 10
R2#

R2#show ip ospf virtual-links
Virtual Link OSPF_VL0 to router 3.3.3.3 is up
  Run as demand circuit
  DoNotAge LSA allowed.
  Transit area 23, via interface Serial1/1, Cost of using 64
  Transmit Delay is 1 sec, State POINT_TO_POINT,
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    Hello due in 00:00:06
    Adjacency State FULL (Hello suppressed)
    Index 2/3, 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
  Message digest authentication enabled
    Youngest key id is 10
R2#

R3#show ip ospf virtual-links
Virtual Link OSPF_VL0 to router 2.2.2.2 is up
  Run as demand circuit
  DoNotAge LSA allowed.
  Transit area 23, via interface Serial1/1, Cost of using 64
  Transmit Delay is 1 sec, State POINT_TO_POINT,
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    Hello due in 00:00:01
    Adjacency State FULL (Hello suppressed)
    Index 1/3, 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
  Message digest authentication enabled
    Youngest key id is 10
R3#

R1#debug ip ospf packet
OSPF packet debugging is on
R1#
*Jul  8 18:49:09.983: OSPF: rcv. v:2 t:1 l:48 rid:2.2.2.2
      aid:0.0.0.0 chk:0 aut:2 keyid:10 seq:0x4FF9D50E from Serial1/0
R1#
*Jul  8 18:49:19.983: OSPF: rcv. v:2 t:1 l:48 rid:2.2.2.2
      aid:0.0.0.0 chk:0 aut:2 keyid:10 seq:0x4FF9D518 from Serial1/0
R1#

R2#debug ip ospf packet
OSPF packet debugging is on
R2#
*Jul  8 18:49:09.643: OSPF: rcv. v:2 t:1 l:48 rid:3.3.3.3
      aid:0.0.0.23 chk:E279 aut:0 auk: from Serial1/1
*Jul  8 18:49:10.179: OSPF: rcv. v:2 t:1 l:48 rid:1.1.1.1
      aid:0.0.0.0 chk:0 aut:2 keyid:10 seq:0x4FF9D50E from Serial1/0
R2#
*Jul  8 18:49:19.607: OSPF: rcv. v:2 t:1 l:48 rid:3.3.3.3
      aid:0.0.0.23 chk:E279 aut:0 auk: from Serial1/1
*Jul  8 18:49:20.187: OSPF: rcv. v:2 t:1 l:48 rid:1.1.1.1
      aid:0.0.0.0 chk:0 aut:2 keyid:10 seq:0x4FF9D518 from Serial1/0
R2#

R1#ping 4.4.4.4

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 4.4.4.4, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 52/87/124 ms
R1#

R4#ping 1.1.1.1

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 48/96/124 ms
R4#

Observations:

·         OSPF authentication successfully configured for Area-0.