Wednesday, 28 December 2016

BEST INTERVIEW QUESTION OSPF LSA TYPES Q7

LSA 1 (Router LSA)
Generated by all routers in an area to describe their directly attached links (Intra-area routes).
 These do not leave the area.

LSA 2 (Network LSA)
Generated by the DR of a broadcast or Nonbroadcast segment to describe the neighbors connected to
the segment. These do not leave the area.

LSA 3 (Network Summary LSA)
Generated by the ABR to describe a route to neighbors outside the area. (Inter-area routes)

LSA 4 (ASBR Summary LSA)
Generated by the ABR to describe a route to an ASBR to neighbors outside the area.

LSA 5 (AS External LSA)
Generated by ASBR to describe routes redistributed into the area. These routes appear as E1 or E2 in
the routing table.  E2 (default) uses a static cost throughout the OSPF domain as it only takes the
cost into account that is reported at redistribution. E1 uses a cumulative cost of the cost reported
into the OSPF domain at redistribution plus the local cost to the ASBR.

LSA 6 (Multicast LSA)
Not supported on Cisco routers.

LSA 7 (NSSA External LSA)
Generated by an ASBR inside a NSSA to describe routes redistributed into the NSSA.
LSA 7 is translated into LSA 5 as it leaves the NSSA. These routes appear as N1 or N2
 in the ip routing table inside the NSSA. Much like LSA 5, N2 is a static cost while N1
 is a cumulative cost that includes the cost upto the ASBR.

LAB ON LSA TYPES:


Configuration of R1

!
hostname R1
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 5
ip cef
!
!
!
!
ip auth-proxy max-nodata-conns 3
ip admission max-nodata-conns 3
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
interface Loopback1
 ip address 1.1.1.1 255.255.255.255
!
interface FastEthernet0/0
 no ip address
 shutdown
 duplex auto
 speed auto
!
interface Serial0/0
 ip address 10.1.12.1 255.255.255.252
 clock rate 2000000
!
interface FastEthernet0/1
 no ip address
 shutdown
 duplex auto
 speed auto
!
interface Serial0/1
 no ip address
 shutdown
 clock rate 2000000
!
router ospf 1
 log-adjacency-changes
 network 1.1.1.1 0.0.0.0 area 1
 network 10.1.12.0 0.0.0.3 area 0
!
ip forward-protocol nd
!
!
ip http server
no ip http secure-server
!
!
!
!
control-plane
!
!
!
!
!
!
!
!
!
!
line con 0
line aux 0
line vty 0 4
 login
!
!
end

R1#
R1#sh ip osp da
R1#sh ip ospf dat
R1#sh ip ospf database

            OSPF Router with ID (1.1.1.1) (Process ID 1)

                Router Link States (Area 0)

Link ID         ADV Router      Age         Seq#       Checksum Link count
1.1.1.1         1.1.1.1         1115        0x80000004 0x00E182 2
2.2.2.2         2.2.2.2         995         0x80000004 0x00DF6F 4
10.1.34.1       10.1.34.1       535         0x80000004 0x0052A4 2

                Summary Net Link States (Area 0)

Link ID         ADV Router      Age         Seq#       Checksum
1.1.1.1         1.1.1.1         1111        0x80000001 0x0047EC
10.1.34.0       10.1.34.1       1058        0x80000001 0x009C08

                Router Link States (Area 1)

Link ID         ADV Router      Age         Seq#       Checksum Link count
1.1.1.1         1.1.1.1         1115        0x80000001 0x00D351 1

                Summary Net Link States (Area 1)

Link ID         ADV Router      Age         Seq#       Checksum
10.1.12.0       1.1.1.1         1116        0x80000001 0x00C81C
10.1.23.0       1.1.1.1         1121        0x80000001 0x00D1C7
10.1.34.0       1.1.1.1         1060        0x80000001 0x00DA73

                Summary ASB Link States (Area 1)

Link ID         ADV Router      Age         Seq#       Checksum
2.2.2.2         1.1.1.1         994         0x80000001 0x00836C
10.1.34.1       1.1.1.1         533         0x80000001 0x005237

                Type-5 AS External Link States

Link ID         ADV Router      Age         Seq#       Checksum Tag
2.2.2.2         2.2.2.2         999         0x80000001 0x002E64 0
4.4.4.4         10.1.34.1       519         0x80000001 0x009643 0

configuration of R2:

R2#sh run
Building configuration...

Current configuration : 1079 bytes
!
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname R2
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 5
ip cef
!
!
!
!
ip auth-proxy max-nodata-conns 3
ip admission max-nodata-conns 3
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
interface Loopback1
 ip address 2.2.2.2 255.255.255.255
!
interface FastEthernet0/0
 no ip address
 shutdown
 duplex auto
 speed auto
!
interface Serial0/0
 ip address 10.1.12.2 255.255.255.252
 clock rate 2000000
!
interface FastEthernet0/1
 no ip address
 shutdown
 duplex auto
 speed auto
!
interface Serial0/1
 ip address 10.1.23.1 255.255.255.252
 clock rate 2000000
!
router ospf 1
 log-adjacency-changes
 redistribute rip metric 3333 subnets
 network 10.1.12.0 0.0.0.3 area 0
 network 10.1.23.0 0.0.0.3 area 0
!
router rip
 version 2
 network 2.0.0.0
 no auto-summary
!
ip forward-protocol nd
!
!
ip http server
no ip http secure-server
!
!
!
!
control-plane
!
!
!
!
!
!
!
!
!
!
line con 0
line aux 0
line vty 0 4
 login
!
!
end

R2#sh ip os
R2#sh ip ospf data
R2#sh ip ospf database

            OSPF Router with ID (2.2.2.2) (Process ID 1)

                Router Link States (Area 0)

Link ID         ADV Router      Age         Seq#       Checksum Link count
1.1.1.1         1.1.1.1         1205        0x80000004 0x00E182 2
2.2.2.2         2.2.2.2         1082        0x80000004 0x00DF6F 4
10.1.34.1       10.1.34.1       622         0x80000004 0x0052A4 2

                Summary Net Link States (Area 0)

Link ID         ADV Router      Age         Seq#       Checksum
1.1.1.1         1.1.1.1         1200        0x80000001 0x0047EC
10.1.34.0       10.1.34.1       1145        0x80000001 0x009C08

                Type-5 AS External Link States

Link ID         ADV Router      Age         Seq#       Checksum Tag
2.2.2.2         2.2.2.2         1082        0x80000001 0x002E64 0
4.4.4.4         10.1.34.1       602         0x80000001 0x009643 0

configuration of R3:
!
hostname R3
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 5
ip cef
!
!
!
!
ip auth-proxy max-nodata-conns 3
ip admission max-nodata-conns 3
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
interface FastEthernet0/0
 no ip address
 shutdown
 duplex auto
 speed auto
!
interface Serial0/0
 ip address 10.1.34.1 255.255.255.252
 clock rate 2000000
!
interface FastEthernet0/1
 no ip address
 shutdown
 duplex auto
 speed auto
!
interface Serial0/1
 ip address 10.1.23.2 255.255.255.252
 clock rate 2000000
!
router ospf 1
 log-adjacency-changes
 area 2 nssa
 network 10.1.23.0 0.0.0.3 area 0
 network 10.1.34.0 0.0.0.3 area 2
!
ip forward-protocol nd
!
!
ip http server
no ip http secure-server
!
!
!
!
control-plane
!
!
!
!
!
!
!
!
!
!
line con 0
line aux 0
line vty 0 4
 login
!
!
end

R3#sh ip os
R3#sh ip ospf da
R3#sh ip ospf database

            OSPF Router with ID (10.1.34.1) (Process ID 1)

                Router Link States (Area 0)

Link ID         ADV Router      Age         Seq#       Checksum Link count
1.1.1.1         1.1.1.1         1436        0x80000004 0x00E182 2
2.2.2.2         2.2.2.2         1313        0x80000004 0x00DF6F 4
10.1.34.1       10.1.34.1       852         0x80000004 0x0052A4 2

                Summary Net Link States (Area 0)

Link ID         ADV Router      Age         Seq#       Checksum
1.1.1.1         1.1.1.1         1431        0x80000001 0x0047EC
10.1.34.0       10.1.34.1       1374        0x80000001 0x009C08

                Router Link States (Area 2)

Link ID         ADV Router      Age         Seq#       Checksum Link count
4.4.4.4         4.4.4.4         839         0x80000004 0x00E908 2
10.1.34.1       10.1.34.1       840         0x80000005 0x00A32F 2

                Summary Net Link States (Area 2)

Link ID         ADV Router      Age         Seq#       Checksum
1.1.1.1         10.1.34.1       852         0x80000002 0x00B6CB
10.1.12.0       10.1.34.1       859         0x80000002 0x00B5BD
10.1.23.0       10.1.34.1       859         0x80000002 0x00B9EE

                Type-7 AS External Link States (Area 2)

Link ID         ADV Router      Age         Seq#       Checksum Tag
4.4.4.4         4.4.4.4         850         0x80000001 0x00E00D 0

                Type-5 AS External Link States

Link ID         ADV Router      Age         Seq#       Checksum Tag
2.2.2.2         2.2.2.2         1320        0x80000001 0x002E64 0
4.4.4.4         10.1.34.1       838         0x80000001 0x009643 0

configuration of R4:
!
hostname R4
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 5
ip cef
!
!
!
!
ip auth-proxy max-nodata-conns 3
ip admission max-nodata-conns 3
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
interface Loopback1
 ip address 4.4.4.4 255.255.255.255
!
interface FastEthernet0/0
 no ip address
 shutdown
 duplex auto
 speed auto
!
interface Serial0/0
 ip address 10.1.34.2 255.255.255.252
 clock rate 2000000
!
interface FastEthernet0/1
 no ip address
 shutdown
 duplex auto
 speed auto
!
interface Serial0/1
 no ip address
 shutdown
 clock rate 2000000
!
router eigrp 100
 network 4.0.0.0
 no auto-summary
!
router ospf 1
 log-adjacency-changes
 area 2 nssa
 redistribute eigrp 100 metric 4444 subnets
 network 10.1.34.0 0.0.0.3 area 2
!
ip forward-protocol nd
!
!
ip http server
no ip http secure-server
!
!
!
!
control-plane
!
!
!
!
!
!
!
!
!
!
line con 0
line aux 0
line vty 0 4
 login
!
!
end

R4#sh ip os
R4#sh ip ospf da
R4#sh ip ospf database

            OSPF Router with ID (4.4.4.4) (Process ID 1)

                Router Link States (Area 2)

Link ID         ADV Router      Age         Seq#       Checksum Link count
4.4.4.4         4.4.4.4         842         0x80000004 0x00E908 2
10.1.34.1       10.1.34.1       844         0x80000005 0x00A32F 2

                Summary Net Link States (Area 2)

Link ID         ADV Router      Age         Seq#       Checksum
1.1.1.1         10.1.34.1       857         0x80000002 0x00B6CB
10.1.12.0       10.1.34.1       857         0x80000002 0x00B5BD
10.1.23.0       10.1.34.1       857         0x80000002 0x00B9EE

                Type-7 AS External Link States (Area 2)

Link ID         ADV Router      Age         Seq#       Checksum Tag
4.4.4.4         4.4.4.4         846         0x80000001 0x00E00D 0


------------thanx---

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