OSPF
Introduction
- Attributes:
| Type | Link-State |
| Algorithm | Dijkstra |
| Metric | Cost (Bandwidth) |
| AD | 110 |
| Standard | RFC 2328, RFC 2740 |
| Protocols | IP |
| Transport | IP/89 |
| Authentication | Plaintext, MD5 |
| AllSPF Address | 224.0.0.5 |
| AllDR Address | 224.0.0.6 |
- OSPF Hello Packet has TTL=1. It cannot cross a hop.[1]
- Change AD in OSPF:
# router ospf 1 # distance 250 (useful in Protocol Migration) # distance 255 (invalid; do not use these routes)
- Metric Formula
This can be modifiable with cmd:
router ospf 1 auto-cost reference-bandwidth 1000
- All Areas must connect to Area 0.
- All routers in an area have same Topology Table.
- ABR localizes updates to an Area.
- Only ABR & ASBR can do Summarization in OSPF. In EIGRP Summarization can be done anywhere.
- All Areas must connect to Area 0.
- Hello message is sent:
Every 10 sec on Broadcast/Point-to-point network. Every 30 sec on NBMA Network
- Dead Timer is 4 times Hello message
40 sec Broadcast/Point-to-point network. 120 sec NBMA Network
- On receiving a hello, If my Router-ID is already listed, reset Dead Timer, stop further processing, else start Neighbor relationship processing.
- EIGRP keeps a backup path in case primary path fails. OSPF does not keep backup path, so needs to re-run SPF again.
OSPF Databases and Tables
OSPF has 3 Databases used to create 3 Tables:
| Database | Table Name | Description |
|---|---|---|
| Adjacency Database | Neighbor Table |
|
| Link-State Database | Topology Table |
|
| Forwarding Database | Routing Table |
|
Packet types in OSPF
| Type | Packet Name | Description |
|---|---|---|
| 1 | Hello | Discovers Neighbors & builds adjacencies between them |
| 2 | Database Description(DBD) |
|
| 3 | Link-State request(LSR) | Requests specific link-state records from other router |
| 4 | LSU | Sends specifically requested link-state records(contain LSAs) |
| 5 | LSAck |
|
- Hello packet contains:
Router-ID Router Priority Neighbors Area ID Hello/Dead Timers DR/BDR IP Address Netmask Authentication Password
DR BDR
- The DR serves as a common point for all adjacencies on a multiaccess segment
- The BDR also maintains adjacencies with all routers in case the DR fails
- Election does not occur on point-to-point or multipoint links, these routers listen only on 224.0.0.5 address.
- DR preemption will not occur unless the current DR is reset
- DR/BDR is not Area/AS specific; There is a DR/BDR for every shared Segment.
- DROTHER is the name for other routers.
- Router will be in Full state with only DR & BDR; all other routers will be in 2-way state.
- Does not matter much which router becomes DR/BDR; except for Frame relay, where if Router with no access to full topology becomes DR, can cause serious issues.
- Election:
Default priority (0-255) is 1 Highest priority wins 0 cannot be elected In case of tie, Router with Highest Router ID wins election
Virtual Links
- Tunnel formed to join two areas across an intermediate
- Both end routers must share a common area
- At least one end must reside in area 0
- Cannot traverse stub areas
R1> router ospf 1 R1> area 2 virtual-link 10.0.0.1
R2> router ospf 1 R2> area 2 virtual-link 10.0.0.2
10.0.0.1 & 10.0.0.2 are Router-IDs Area 2 is the area of the transit area. R1 & R2 are the ABRs of Area 2 & Area 3.
What is a Demand Circuit
Source: cisco.com
- OSPF sends hellos every 10 seconds and refreshes its LSAs every 30 minutes.
- These functions maintain neighbor relationships and ensure that the link-state databases are accurate and use far less bandwidth than similar functions in RIP & IGRP.
- However, even this amount of traffic is undesirable on demand circuits. Using OSPF demand circuit options suppresses hello and LSA refresh functions.
- OSPF can establish a demand link to form an adjacency and perform initial database synchronization, the adjacency remains active even after Layer 2 of the demand circuit goes down.
- Cisco IOS version 12.1(2)T introduces the flooding reduction feature for OSPF.
- This feature is intended to minimize traffic created by a periodic refresh of LSAs in OSPF domains with large number of LSAs.
- Unlike the OSPF demand circuit feature, flooding reduction is usually configured on leased lines.
- Flooding reduction uses same technique as demand circuits to suppress the periodic LSA refresh.
- This feature is submitted for standardization into the IETF OSPF working group.
- The main difference between flooding reduction and demand circuits is that former suppresses only periodic LSA refreshes; it does not suppress periodic hello packets.
- Thus, the flooding reduction feature does not impair the detection of a neighbor router going down.
ip ospf demand-circuit
Area Summary
- Standard areas
Contain LSAs of type 1, 2, 3, 4, and 5, and may contain an ASBR. The backbone is considered a standard area.
- Stub areas
Contain type 1, 2, and 3 LSAs. Block Type 5 LSAs. A default route is substituted for external routes.
- Totally stubby areas
Only contain type 1 and 2 LSAs, and a single type 3 LSA. Block LSAs Type 3,4,5. The type 3 LSA describes a default route, substituted for all external and inter-area routes.
- Not-so-stubby areas
Implement stub or totally stubby functionality yet contain an ASBR. Type 7 LSAs generated by the ASBR are converted to type 5 by ABRs when entering Backbone Area to be flooded to the rest of the OSPF domain.
LSA
- LSA Details:
- Type 1 - Router LSAs
Sent from a router to other routers in the same area. It contains information regarding the routers interfaces in the same area, relevant interfaces IPs, its adjacent routers on those interfaces and sub networks
- Type 2 - Network LSAs
Generated by the DR on a multi access segment Represents the pseudonode (designated router) for a multiaccess link. Provides similar information to an LSA type 1 for the multi access segment and subnet which it belongs
- Type 3 - Network Summary LSA
Generated by ABRs Contain the subnets & costs but omit the topological data from all subnets in one area and sent to another area via the ABR
- Type 4 - ASBR summary LSA
Generated by ___ Represents ASBRs and are identical in structure to a type 3 LSA and sent when crossing an AS boundary
- Type 5 - AS external LSA
Generated by ASBRs describe a route external to the OSPF domain
- Type 7 - NSSA External LSA
Generated by the ASBR in an NSSA area Used in stub areas in place of a type 5 LSA.
- LSA as per Areas[2]:-
Adjacency
- OSPF neighbor requirements:
- Same area
- Same authentication config
- Same subnet
- Same Hello/Dead interval
- Matching stub flags
- Difference between Adjacency & Neighbor:
- Only Adjacent Routers can sync Link State DB
- Point-to-Point Links: If Neighbors, Adjcency automatically established
- Broadcast Link: Adjacency established with DR & BDR only, rest are in 2-way state[3]
- Point-to-Multipoint:_________
- Neighbor means Physical Connectivity(Direct)
- Adjacency means Database Syncronization
- Neighbor Requirements:
- Hello exchange => Subnet Mask, Subnet Number, Hello/Dead Interval, Area ID, Authentication must match.
- Exchange hellos but not LSAs(2-Way State).
- Adjacency Requirements:
- Exchange LSAs
- Both routers are in Stable(Full) State.
- Still final LSDB is same even in Neighbors as well as Adjacent routers.
OSPF Neighbor Relationship
1. Determine you own Router-ID:
Highest Active Interface IP < HIghest Active Loopback Interface IP < Router-ID Command Router-ID is determined during 1st neighbor establishment process. It only changes when: - OSPF process is restarted (# clear ip ospf process) - Rebooted Router
2. Add Interfaces to Link State Database (Network command):
- Neighbor States[4]
| State | Details |
|---|---|
| 1. Down |
|
| 2. Attempt |
|
| 3. Init |
|
| 4. 2-Way |
|
| 5. ExStart |
|
| 6. Exchange |
|
| 7. Loading |
|
| 8. Full |
|
Route Types
- OSPF external type 1 - E1
- Metric Increments as they traverse through network.
- Used when multiple exit paths exist
[Ext network]---------[R1]-----------[R2]
200 10
Cost for E1 route in R2 will be 200 + 10 = 210
- OSPF external type 2 - E2 (Default)
- Cost does not increment in Network
- Used only when one Exit point exists.
- Bit easy for processor.
[Ext network]---------[R1]-----------[R2]
200 10
Cost for E2 route in R2 will be 200
- OSPF NSSA external type 1 - N1
 This section is under construction.
|
- OSPF NSSA external type 2 - N2
| This section is under construction.
|
- OSPF inter area - IA
| This section is under construction.
|
- Route Selection Hierarchy - E1, E2, N1, N2
| This section is under construction.
|
R&S Quick Notes
The Neighbor IP used with OSPF distance command is the Neighbors Router-ID.
“area range” summarize type 3 LSA’.
“summary-address” summarize type 5 & 7 LSA’s.
Auto-cost reference BW (Default = 100mb), formula = Ref-BW/Int-Bw.
Switches do no support the interface command “ip ospf {pid} area {area-id}” .
OSPF path selection: O > O*IA > O*E1 > O*E2.
Using E1 metric type : Packets will be routed out the closest exit point of the network.
Using E2 metric type : If you want packets to exit your network at the closest point to their external destination.
Don’t forget with hub and spoke topology, “ip ospf priority 0″.
PITFALL, when forbid to use RID, Loopbacks created later on might change the DR on you network after a reload.
PITFALL, when forbid to use RID, Later requested to configure the same loopback on two routers, could break your adjacencies, as two router cant peer with the same RID.
“no capability transit” – Mimics OSPFv1 behaviour for all data traffic to pass through Area-0.
“max-metric” – Configures OSPF stub configurations
“max-lsa” – Limit amount of non-local LSA’s
“timers throttle lsa all” – Slow down update rate.
“timers pacing lsa-group” – Group more LSA’s together in updates.
“no ip ospf flood-reduction” – Disables every 30-min LSA DB refresh.
“ip ospf database filter all out” – Breaks RFC, Stop sending LSA’s, but still receive LSA’s
Concept Recap
Protocol Number = 89, TTL=1, DES IP = 224.0.0.5 & 6
Network Types:
PTP:
No DR, BDR and ospf packets are sent to MC address.
Broadcast: (ethernet, token ring, FDDI)
DR, BDR election occurs and communicates using .5 and .6 address.
DR and BDR listen to .5 and .6 addresses.
NBMA network: (Frame relay, ATM)
Manual configuration of neighbors and DR/BDR.
All communication via unicast
Point to multipoint:
No DR and BDR. Neighbor statement not necessary.
Unicast
Virtual link:
Packets are unicast.
OSPF packet types:
Hello – type 1
Database description – type 2
LS request – type 3
LS update – type 4
LS ACK – type 5
To bring neighborship up, following fields should be matched:
Hello interval, Dead interval, area ID, network mask, option fields and authentication, if any
Neighborship will not form via secondary address. Other words, router will not generate hello packet with SRC IP = secondary IP.
DR/BDR election:
Highest Priority
Tie, highest router ID
Tie, highest interface address.
No preempt. So, first come will elect as DR, BDR, DRother. So, always start the router which has to be DR and then BDR and then other routers.
Priority=0 means ineligible to become DR/BDR.
When interface comes up, it sets DR,BDR to 0.0.0.0 and wait for ‘wait timer’= router dead interval. Within that period, if it receives hello with DR/BDR filled, accept those. Else if the time period elapse, move to BDR and then to DR.
Timers:
Default H=10 sec and D= 40 sec
InfTransDelay = 1 sec. change by “ip ospf transmit-delay’
RxmtInterval = 5 sec. Change by “ip ospf retramit-delay’
Neighbor state machine:
Down: at initial
Attempt: Only in NBMA
Init: Hello packet received. But couldn’t see our ID in its active neighbor list.
2-way:Could see our ID in neighbor list
Exstart: Start electing master/slave to exchange DBD packets. Highest router ID becomes master.
Exchange: exchange the LSA headers using DBD packets.
Loading: Syn the LSD using LS request and LS update. In real scenario, both Exchange and loading occurs parallel.
Full: Database was sync-ed.
DBD packet:
Have Interface MTU settings.
Initial(I) bit, More (M) bit and Master/Slave (MS) bit
First DBD packet sent with I/M/MS = 1/1/1 with seq =x
Neighbor sends DBD with I/M/MS = 1/1/1 with seq = y
After master selection, slave send DBD with I/M/MS = 0/1/0 with seq = master seq + 1.
Retransmission packets are always unicast.
Use stub concept and summarization to reduce memory and CPU utilization.
Sequence number, checksum and age uniquely defines as LSA:
Seq #:
From 0×80000001 to 0x7fffffff
If the seq# reaches 0x7ffffff, router flushes those LSA with age = MAXage.
Checksum:
Calculated entire LSA except age field.
Checksum is verified every 5 mins as it resides in LSD.
Age:
0 to 3600 (1 Hr-MaxAge)
Age increments when it resides in LSA and also incremented by ‘Infdelay’ value as it transits an interface.
Virtual Links:
Must be configured between 2 ABRs alone.
Transit area must have full routing information.
Transit area cannot be stub.
Usually it is the worst design and needs to be changed.
Can temporarily deploy to avoid partitioned area.
LSA types:
Router LSA:
Type-1. Generated by all routers with all active networks which has ospf configured.
Show ip ospf database router
LSAs are flooded within an area only.
Above command should have same output in all routers in an area. Seq #,checksum etc should be same.
Network LSA:
Type-2: Generated by the DR with network ID of the BC network.
Show ip ospf database network
No metric field as in router LSA.
LSAs are flooded within an area only.
N/w summary LSA:
Type-3: Generated by ABR to advertise the networks in another area.
If there are multiple routes to a destination, ABR advertise only the lowest cost route to its area along with cost metric.
Means, intra area routers use distance-vector protocol to know about inter-area routes.
Show ip ospf database summary
ASBR summary LSA:
Type-4; Same as summary LSA except the destination advertised by ABR is ASBR.
Show ip ospf database asbr-summary
AS external LSA:
Type-5; Advertise routes external to OSPF domain.
Typically redistribution of RIP, ISIS etc
Show ip ospf database external
Not associated with any area.
Group-Membership LSA:
Type-6; Used in MOSPF- multicast ospf
NSSA external LSA:
Type-7; originated by ASBR within NSSA
Show ip ospf database nssa-external
Flooded within NSSA region only.
ASBR can set/reset “P-bit” under “options field” of every LSA.
Only if NSSA-ABR receives type-7 LSA with P-bit set, it will translate into type-5 LSA and flood to other areas.
External Attribute LSA:
Type-8. Can be used as alternative to iBGP
Not deployed yet.
Opaque LSA:
Type- 9,10,11
Extension to OSPF. Used for TE in MPLS.
Areas:
Backbone area:
Area-0. Need for inter-area communication.
If there is only one area, no need for area-0
All types of LSAs except type-7 can be seen.
Stub area:
Single exist point for inter-area communication. But still can have more than one ABR.
Have info about OSPF domain areas. Both intra and inter-area routes.
No info about external (other domain) routes. Hence, ABR sends a default route.
Type-1,2 and 3 LSAs can be seen.
All the routers should have “E-bit” set to 0 in their hello packets to form adjacency.
Command: “area x stub”
Totally stubby area:
Router has info about its area alone. No info about inter-area routes.
Can see type-1, type-2 LSAs and single default route type-3 LSA by ABR.
Command: ‘area x stub no-summary’
NSSA:
Same property as stub area (not totally-stub area) with exception of allowing other domain routes as Lype-7 LSA.
No default route from ABR. (unless ‘default-info originate’ CLI configured where N2 default route (or) ‘area x nssa no-summary’ configured. In later, IA routes will not be available and default route has IA tag)
Can see Type-1,2,3,4 and type-7 LSAs.
Command: ‘area x nssa’.
Path types:
Intra-area paths
Inter-area paths. Denoted by “IA” in show ip route.
E1:
Cost = advertised by ASBR + cost to ASBR
E2:
Cost = advertised by ASBR. Enabled by default.
If there is only one ASBR in OSPF, there is no necessity of adding cost to ASBR. Hence E2 is default.
If there are more than on ASBR, enable E1.
Authentication:
No authentication: Type-0
Simple password: Type-1
MD5 password: Type-2
Few points:
Router LSA of ABR will have “B-bit” set in router-lsa packet
Router LSA of ASBR will have “E-bit” set in router-lsa packet
When NSSA ABR, translates type-7 LSA to type-5 LSA, it advertise with “Advertising Router” field set to its own router ID and it changes to ASBR. It could be confirmed by seeing “E” bit set in router LSA packet.
“Options field” in OSPF hello, DBD and every LSA: From MSB
DN – used in MPLS VPN. To detect loop.
O- Set to indicate routers’ opaque LSA support.
DC- OSPF over Demand circuit.
EA – external attribute support
N/P bit
N bit in hello: Set to indicate support for NSSA external LSAs. Mismatch will not bring adjacency
P-bit in NSSA external LSA header: to inform ABR to translate T-7 to T-5 LSAs.
MC – set to indicate multicast ospf capability
E – E bit=0 to indicate stub area.
MT – set to indicate Multi-topology OSPF support. Under development.
Troubleshooting point of view: few
Neighborship not coming UP:
Check for Hello packet parameter match
Network ID in correct area??
Access-list blocking OSPF packets??
Packet dropped on the way to CP incase if interface multicast count is incrementing??
Check Stub-area configuration?? Virtual link via stub area??
Neighborship UP but no advertised routes in database:
Enable debug and check for LSupdate packets.
Routes in OSPF database but not in routing table:
Routes via another protocol which has AD less than OSPFs??
One end of router has “ip ospf network PTP’ whereas other end router has default BC network type.
In case of external routes not installed in routing table, check whether the forwarding address is reachable. If not, configure ‘suppress-fa’ option at the NSSA ABR.
If an LSA has less age or high sequence number among others, we need to look for why this network was keep flapping and flooding updates. Might be reason for high CPU utilization.
Observations:
ABR with area-1 and area-2 only.
Routes from area-1 are not leaked into area-2 using type-3 network summary LSA.
Authentication:
Configure ‘ip ospf authentication’ to change to type-1. No user-defined password possible.
For loopback IP to become router-id either remove and reapply the ospf configuration or configure ‘router-id’ command.
DBD packet can have multiple LSA headers each can be of different type.(T1/T2)
When we change the network type to ‘point-point’, the interface will send a hello with DR,BDR =0 and no neighbor IDs in active neighbor field. This makes other end router to move to init.
In BC network: DBD, LS request and LS updates are exchanged via unicast. LS update (repeat) and LS ACK are sent to 224.0.0.5
In PTP, all communications via 224.0.0.5
Changing hello packet parameters (hello interval, dead interval etc) on one end makes the other end router to ignore those hello packets which has modified parameters.
Both side of router configured with priority =0 with default n/w type, they will stuck in 2way/DRother.
In an already existing stub network, if we change to totally stub, border router send an update with IA routes’ age= 3600 for flushing from database. Same as in ‘clear ip ospf process’
Redistributing RIP to ospf in a router which is inside a stub network:
“%OSPF-4-ASBR_WITHOUT_VALID_AREA: Router is currently an ASBR while having only one area which is a stub area”
Summarization has no effect of external routes (E1/E2).
LAB
Troubleshooting
- If OSPF is stuck in INIT State, check Netmask, Hello/Dead Timer, Area ID, Authentication password.
- On a shared/ethernet network, only 2 router, DR & BDR will form full relationship, all others will stay in 2-way state.[5]
- If OSPF is stuck in ExStart State, MTU mismatch may be the cause, as it is requirement to successfully pass DBD Packets.
Matching MTU is not a Adjacency Requirement, but is required to successfully pass Database Descriptor Packets
- In OSPF, MTU Mismatch causes neighbors swinging between ExStart state to Down state
Mar 1 00:10:09.535: %OSPF-5-ADJCHG: Process 1, Nbr 10.10.10.1 on Ethernet0/0 from EXSTART to DOWN, Neighbor Down: Too many retransmissions
Basic OSPF Lab
GNS3 Project: File:CBT Nuggets OSPF Lab.zip
Objectives
1. Config OSPF:
R1 will act as ASBR by redistributing static routes into OSPF. Metric of these routes should not increase as they pass through network and should have initial OSPF cost of 200. All routers have should have router-id as their hostname.
2. Find out which router is DR & BDR.
3. R1 should become DR, R2 & R3 should not be DR or BDR.
Find out relation between R1 & R2; R2 & R3.
4. Implement summarization on ABRs to make routing table most efficient
5. Implement summarization on ASBRs; Summary routes should have same attributes as original routes.
6. Change Metric to accurately calculate cost for Gigabit Ethernet links.
Configurations
R1 Config:
! interface Ethernet0/0 ip address 172.30.0.1 255.255.255.0 half-duplex ! ! router ospf 1 router-id 1.1.1.1 log-adjacency-changes auto-cost reference-bandwidth 1000 summary-address 172.16.0.0 255.255.252.0 redistribute static metric 200 subnets network 172.30.0.1 0.0.0.0 area 0 ! ! ip route 172.16.0.0 255.255.255.0 Null0 ip route 172.16.1.0 255.255.255.0 Null0 ip route 172.16.2.0 255.255.255.0 Null0 ip route 172.16.3.0 255.255.255.0 Null0 !
R2 Config:
! interface Ethernet0/0 ip address 172.30.0.2 255.255.255.0 ip ospf priority 0 half-duplex ! interface Serial1/0 ip address 172.30.10.2 255.255.255.0 serial restart-delay 0 ! ! router ospf 1 router-id 2.2.2.2 log-adjacency-changes auto-cost reference-bandwidth 1000 area 10 range 10.10.0.0 255.255.252.0 network 172.30.0.2 0.0.0.0 area 0 network 172.30.10.2 0.0.0.0 area 10 ! !
R3 Config:
! interface Ethernet0/0 ip address 172.30.0.3 255.255.255.0 ip ospf priority 0 half-duplex ! ! interface Serial1/0 ip address 172.30.20.3 255.255.255.0 serial restart-delay 0 ! ! router ospf 1 router-id 3.3.3.3 log-adjacency-changes auto-cost reference-bandwidth 1000 area 20 range 10.20.0.0 255.255.252.0 network 172.30.0.3 0.0.0.0 area 0 network 172.30.20.3 0.0.0.0 area 20 ! !
R4 Config:
interface Loopback1 ip address 10.20.0.1 255.255.255.0 ! interface Loopback2 ip address 10.20.1.1 255.255.255.0 ! interface Loopback3 ip address 10.20.2.1 255.255.255.0 ! interface Loopback4 ip address 10.20.3.1 255.255.255.0 ! ! interface Serial1/0 ip address 172.30.20.4 255.255.255.0 serial restart-delay 0 ! ! router ospf 1 router-id 4.4.4.4 log-adjacency-changes auto-cost reference-bandwidth 1000 network 10.0.0.0 0.255.255.255 area 20 network 172.30.20.4 0.0.0.0 area 20 ! !
R5 Config:
! interface Loopback1 ip address 10.10.0.1 255.255.255.0 ip ospf network point-to-point ! interface Loopback2 ip address 10.10.1.1 255.255.255.0 ! interface Loopback3 ip address 10.10.2.1 255.255.255.0 ! interface Loopback4 ip address 10.10.3.1 255.255.255.0 ! ! interface Serial1/0 ip address 172.30.10.5 255.255.255.0 serial restart-delay 0 ! ! router ospf 1 router-id 5.5.5.5 log-adjacency-changes auto-cost reference-bandwidth 1000 network 10.10.0.0 0.0.255.255 area 10 network 172.30.10.5 0.0.0.0 area 10 ! !
Command Line Outputs
- show ip interface brief
- R1:
R1# show ip interface brief Interface IP-Address OK? Method Status Protocol Ethernet0/0 172.30.0.1 YES manual up up Ethernet0/1 unassigned YES unset administratively down down Ethernet0/2 unassigned YES unset administratively down down Ethernet0/3 unassigned YES unset administratively down down Serial1/0 unassigned YES unset administratively down down Serial1/1 unassigned YES unset administratively down down Serial1/2 unassigned YES unset administratively down down Serial1/3 unassigned YES unset administratively down down
- R2:
R2#show ip interface brief Interface IP-Address OK? Method Status Protocol Ethernet0/0 172.30.0.2 YES manual up up Ethernet0/1 unassigned YES unset administratively down down Ethernet0/2 unassigned YES unset administratively down down Ethernet0/3 unassigned YES unset administratively down down Serial1/0 172.30.10.2 YES manual up up Serial1/1 unassigned YES unset administratively down down Serial1/2 unassigned YES unset administratively down down Serial1/3 unassigned YES unset administratively down down
- R3:
R3#show ip interface brief Interface IP-Address OK? Method Status Protocol Ethernet0/0 172.30.0.3 YES manual up up Ethernet0/1 unassigned YES unset administratively down down Ethernet0/2 unassigned YES unset administratively down down Ethernet0/3 unassigned YES unset administratively down down Serial1/0 172.30.20.3 YES manual up up Serial1/1 unassigned YES unset administratively down down Serial1/2 unassigned YES unset administratively down down Serial1/3 unassigned YES unset administratively down down
- R4:
R4# show ip interface brief Interface IP-Address OK? Method Status Protocol Ethernet0/0 unassigned YES unset administratively down down Ethernet0/1 unassigned YES unset administratively down down Ethernet0/2 unassigned YES unset administratively down down Ethernet0/3 unassigned YES unset administratively down down Serial1/0 172.30.20.4 YES manual up up Serial1/1 unassigned YES unset administratively down down Serial1/2 unassigned YES unset administratively down down Serial1/3 unassigned YES unset administratively down down Loopback1 10.20.0.1 YES manual up up Loopback2 10.20.1.1 YES manual up up Loopback3 10.20.2.1 YES manual up up Loopback4 10.20.3.1 YES manual up up
- R5:
R5#show ip interface brief Interface IP-Address OK? Method Status Protocol Ethernet0/0 unassigned YES unset administratively down down Ethernet0/1 unassigned YES unset administratively down down Ethernet0/2 unassigned YES unset administratively down down Ethernet0/3 unassigned YES unset administratively down down Serial1/0 172.30.10.5 YES manual up up Serial1/1 unassigned YES unset administratively down down Serial1/2 unassigned YES unset administratively down down Serial1/3 unassigned YES unset administratively down down Loopback1 10.10.0.1 YES manual up up Loopback2 10.10.1.1 YES manual up up Loopback3 10.10.2.1 YES manual up up Loopback4 10.10.3.1 YES manual up up
- Routing Tables
- R1:
172.16.0.0/16 is variably subnetted, 5 subnets, 2 masks
S 172.16.0.0/24 is directly connected, Null0
O 172.16.0.0/22 is a summary, 01:05:49, Null0
S 172.16.1.0/24 is directly connected, Null0
S 172.16.2.0/24 is directly connected, Null0
S 172.16.3.0/24 is directly connected, Null0
172.30.0.0/24 is subnetted, 3 subnets
O IA 172.30.20.0 [110/747] via 172.30.0.3, 00:53:45, Ethernet0/0
C 172.30.0.0 is directly connected, Ethernet0/0
O IA 172.30.10.0 [110/747] via 172.30.0.2, 00:53:46, Ethernet0/0
10.0.0.0/22 is subnetted, 2 subnets
O IA 10.10.0.0 [110/748] via 172.30.0.2, 00:53:46, Ethernet0/0
O IA 10.20.0.0 [110/748] via 172.30.0.3, 00:53:46, Ethernet0/0
- R2:
172.16.0.0/22 is subnetted, 1 subnets
O E2 172.16.0.0 [110/200] via 172.30.0.1, 00:53:15, Ethernet0/0
172.30.0.0/24 is subnetted, 3 subnets
O IA 172.30.20.0 [110/747] via 172.30.0.3, 00:53:15, Ethernet0/0
C 172.30.0.0 is directly connected, Ethernet0/0
C 172.30.10.0 is directly connected, Serial1/0
10.0.0.0/8 is variably subnetted, 6 subnets, 3 masks
O 10.10.1.1/32 [110/648] via 172.30.10.5, 00:53:15, Serial1/0
O 10.10.0.0/24 [110/648] via 172.30.10.5, 00:53:17, Serial1/0
O 10.10.0.0/22 is a summary, 00:53:17, Null0
O 10.10.3.1/32 [110/648] via 172.30.10.5, 00:53:17, Serial1/0
O 10.10.2.1/32 [110/648] via 172.30.10.5, 00:53:17, Serial1/0
O IA 10.20.0.0/22 [110/748] via 172.30.0.3, 00:53:17, Ethernet0/0
- R3:
172.16.0.0/22 is subnetted, 1 subnets
O E2 172.16.0.0 [110/200] via 172.30.0.1, 00:53:37, Ethernet0/0
172.30.0.0/24 is subnetted, 3 subnets
C 172.30.20.0 is directly connected, Serial1/0
C 172.30.0.0 is directly connected, Ethernet0/0
O IA 172.30.10.0 [110/747] via 172.30.0.2, 00:53:37, Ethernet0/0
10.0.0.0/8 is variably subnetted, 6 subnets, 2 masks
O IA 10.10.0.0/22 [110/748] via 172.30.0.2, 00:53:37, Ethernet0/0
O 10.20.3.1/32 [110/648] via 172.30.20.4, 00:53:38, Serial1/0
O 10.20.2.1/32 [110/648] via 172.30.20.4, 00:53:38, Serial1/0
O 10.20.1.1/32 [110/648] via 172.30.20.4, 00:53:38, Serial1/0
O 10.20.0.0/22 is a summary, 00:53:38, Null0
O 10.20.0.1/32 [110/648] via 172.30.20.4, 00:53:38, Serial1/0
- R4:
172.16.0.0/22 is subnetted, 1 subnets
O E2 172.16.0.0 [110/200] via 172.30.20.3, 00:53:42, Serial1/0
172.30.0.0/24 is subnetted, 3 subnets
C 172.30.20.0 is directly connected, Serial1/0
O IA 172.30.0.0 [110/747] via 172.30.20.3, 00:53:42, Serial1/0
O IA 172.30.10.0 [110/1394] via 172.30.20.3, 00:53:42, Serial1/0
10.0.0.0/8 is variably subnetted, 5 subnets, 2 masks
O IA 10.10.0.0/22 [110/1395] via 172.30.20.3, 00:53:42, Serial1/0
C 10.20.2.0/24 is directly connected, Loopback3
C 10.20.3.0/24 is directly connected, Loopback4
C 10.20.0.0/24 is directly connected, Loopback1
C 10.20.1.0/24 is directly connected, Loopback2
- R5:
172.16.0.0/22 is subnetted, 1 subnets
O E2 172.16.0.0 [110/200] via 172.30.10.2, 00:53:27, Serial1/0
172.30.0.0/24 is subnetted, 3 subnets
O IA 172.30.20.0 [110/1394] via 172.30.10.2, 00:53:27, Serial1/0
O IA 172.30.0.0 [110/747] via 172.30.10.2, 00:53:27, Serial1/0
C 172.30.10.0 is directly connected, Serial1/0
10.0.0.0/8 is variably subnetted, 5 subnets, 2 masks
C 10.10.0.0/24 is directly connected, Loopback1
C 10.10.1.0/24 is directly connected, Loopback2
C 10.10.2.0/24 is directly connected, Loopback3
C 10.10.3.0/24 is directly connected, Loopback4
O IA 10.20.0.0/22 [110/1395] via 172.30.10.2, 00:53:29, Serial1/0
- Topology Tables
- R1:
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 1583 0x80000009 0x0029FC 1
2.2.2.2 2.2.2.2 1320 0x80000007 0x00EB34 1
3.3.3.3 3.3.3.3 1425 0x8000000E 0x009F70 1
Net Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
172.30.0.1 1.1.1.1 82 0x80000004 0x0098B2
Summary Net Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
10.10.0.0 2.2.2.2 1320 0x80000005 0x00A2F2
10.20.0.0 3.3.3.3 1425 0x80000003 0x001079
172.30.10.0 2.2.2.2 1320 0x80000004 0x0008CB
172.30.20.0 3.3.3.3 1425 0x8000000A 0x006F50
Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
172.16.0.0 1.1.1.1 82 0x80000006 0x003AEE 0
- R2:
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 1600 0x80000009 0x0029FC 1
2.2.2.2 2.2.2.2 1335 0x80000007 0x00EB34 1
3.3.3.3 3.3.3.3 1442 0x8000000E 0x009F70 1
Net Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
172.30.0.1 1.1.1.1 98 0x80000004 0x0098B2
Summary Net Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
10.10.0.0 2.2.2.2 1335 0x80000005 0x00A2F2
10.20.0.0 3.3.3.3 1442 0x80000003 0x001079
172.30.10.0 2.2.2.2 1335 0x80000004 0x0008CB
172.30.20.0 3.3.3.3 1442 0x8000000A 0x006F50
Router Link States (Area 10)
Link ID ADV Router Age Seq# Checksum Link count
2.2.2.2 2.2.2.2 1335 0x8000000B 0x0072C4 2
5.5.5.5 5.5.5.5 1323 0x8000000B 0x003F4C 6
Summary Net Link States (Area 10)
Link ID ADV Router Age Seq# Checksum
10.20.0.0 2.2.2.2 1337 0x80000004 0x001810
172.30.0.0 2.2.2.2 1337 0x80000004 0x0005FD
172.30.20.0 2.2.2.2 1337 0x80000005 0x0083E0
Summary ASB Link States (Area 10)
Link ID ADV Router Age Seq# Checksum
1.1.1.1 2.2.2.2 1337 0x80000004 0x00F6D1
Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
172.16.0.0 1.1.1.1 101 0x80000006 0x003AEE 0
- R3:
R3#sh ip ospf database
OSPF Router with ID (3.3.3.3) (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 1606 0x80000009 0x0029FC 1
2.2.2.2 2.2.2.2 1343 0x80000007 0x00EB34 1
3.3.3.3 3.3.3.3 1446 0x8000000E 0x009F70 1
Net Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
172.30.0.1 1.1.1.1 105 0x80000004 0x0098B2
Summary Net Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
10.10.0.0 2.2.2.2 1343 0x80000005 0x00A2F2
10.20.0.0 3.3.3.3 1446 0x80000003 0x001079
172.30.10.0 2.2.2.2 1343 0x80000004 0x0008CB
172.30.20.0 3.3.3.3 1446 0x8000000A 0x006F50
Router Link States (Area 20)
Link ID ADV Router Age Seq# Checksum Link count
3.3.3.3 3.3.3.3 1446 0x8000000D 0x0063B8 2
4.4.4.4 4.4.4.4 1325 0x8000000B 0x0070E2 6
Summary Net Link States (Area 20)
Link ID ADV Router Age Seq# Checksum
10.10.0.0 3.3.3.3 1447 0x80000007 0x006CBE
172.30.0.0 3.3.3.3 1447 0x8000000A 0x00DA1E
172.30.10.0 3.3.3.3 1447 0x80000005 0x00D396
Summary ASB Link States (Area 20)
Link ID ADV Router Age Seq# Checksum
1.1.1.1 3.3.3.3 1447 0x80000004 0x00D8EB
Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
172.16.0.0 1.1.1.1 106 0x80000006 0x003AEE 0
- R4:
R4#sh ip ospf database
OSPF Router with ID (4.4.4.4) (Process ID 1)
Router Link States (Area 20)
Link ID ADV Router Age Seq# Checksum Link count
3.3.3.3 3.3.3.3 1453 0x8000000D 0x0063B8 2
4.4.4.4 4.4.4.4 1329 0x8000000B 0x0070E2 6
Summary Net Link States (Area 20)
Link ID ADV Router Age Seq# Checksum
10.10.0.0 3.3.3.3 1453 0x80000007 0x006CBE
172.30.0.0 3.3.3.3 1453 0x8000000A 0x00DA1E
172.30.10.0 3.3.3.3 1453 0x80000005 0x00D396
Summary ASB Link States (Area 20)
Link ID ADV Router Age Seq# Checksum
1.1.1.1 3.3.3.3 1453 0x80000004 0x00D8EB
Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
172.16.0.0 1.1.1.1 112 0x80000006 0x003AEE 0
- R5:
R5#sh ip ospf database
OSPF Router with ID (5.5.5.5) (Process ID 1)
Router Link States (Area 10)
Link ID ADV Router Age Seq# Checksum Link count
2.2.2.2 2.2.2.2 1353 0x8000000B 0x0072C4 2
5.5.5.5 5.5.5.5 1338 0x8000000B 0x003F4C 6
Summary Net Link States (Area 10)
Link ID ADV Router Age Seq# Checksum
10.20.0.0 2.2.2.2 1353 0x80000004 0x001810
172.30.0.0 2.2.2.2 1353 0x80000004 0x0005FD
172.30.20.0 2.2.2.2 1353 0x80000005 0x0083E0
Summary ASB Link States (Area 10)
Link ID ADV Router Age Seq# Checksum
1.1.1.1 2.2.2.2 1353 0x80000004 0x00F6D1
Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
172.16.0.0 1.1.1.1 117 0x80000006 0x003AEE 0
- Neighbor Table
- R1:
R1#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 2.2.2.2 0 FULL/DROTHER 00:00:30 172.30.0.2 Ethernet0/0 3.3.3.3 0 FULL/DROTHER 00:00:34 172.30.0.3 Ethernet0/0
- R2:
R2#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 1.1.1.1 1 FULL/DR 00:00:32 172.30.0.1 Ethernet0/0 3.3.3.3 0 2WAY/DROTHER 00:00:35 172.30.0.3 Ethernet0/0 5.5.5.5 0 FULL/ - 00:00:39 172.30.10.5 Serial1/0
- R3:
R3#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 1.1.1.1 1 FULL/DR 00:00:39 172.30.0.1 Ethernet0/0 2.2.2.2 0 2WAY/DROTHER 00:00:39 172.30.0.2 Ethernet0/0 4.4.4.4 0 FULL/ - 00:00:39 172.30.20.4 Serial1/0
- R4:
R4#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 3.3.3.3 0 FULL/ - 00:00:36 172.30.20.3 Serial1/0
- R5:
R5#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 2.2.2.2 0 FULL/ - 00:00:34 172.30.10.2 Serial1/0
- Show ip ospf interface
- R1:
R1#show ip ospf interface
Ethernet0/0 is up, line protocol is up
Internet Address 172.30.0.1/24, Area 0
Process ID 1, Router ID 1.1.1.1, Network Type BROADCAST, Cost: 100
Transmit Delay is 1 sec, State DR, Priority 1
Designated Router (ID) 1.1.1.1, Interface address 172.30.0.1
No backup designated router on this network
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
oob-resync timeout 40
Hello due in 00:00:09
Supports Link-local Signaling (LLS)
Index 1/1, 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 2, Adjacent neighbor count is 2
Adjacent with neighbor 2.2.2.2
Adjacent with neighbor 3.3.3.3
Suppress hello for 0 neighbor(s)
- R2:
R2#show ip ospf interface
Ethernet0/0 is up, line protocol is up
Internet Address 172.30.0.2/24, Area 0
Process ID 1, Router ID 2.2.2.2, Network Type BROADCAST, Cost: 100
Transmit Delay is 1 sec, State DROTHER, Priority 0
Designated Router (ID) 1.1.1.1, Interface address 172.30.0.1
No backup designated router on this network
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
oob-resync timeout 40
Hello due in 00:00:06
Supports Link-local Signaling (LLS)
Index 1/1, flood queue length 0
Next 0x0(0)/0x0(0)
Last flood scan length is 2, maximum is 6
Last flood scan time is 0 msec, maximum is 4 msec
Neighbor Count is 2, Adjacent neighbor count is 1
Adjacent with neighbor 1.1.1.1 (Designated Router)
Suppress hello for 0 neighbor(s)
Serial1/0 is up, line protocol is up
Internet Address 172.30.10.2/24, Area 10
Process ID 1, Router ID 2.2.2.2, Network Type POINT_TO_POINT, Cost: 647
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 00:00:04
Supports Link-local Signaling (LLS)
Index 1/2, flood queue length 0
Next 0x0(0)/0x0(0)
Last flood scan length is 1, maximum is 7
Last flood scan time is 4 msec, maximum is 4 msec
Neighbor Count is 1, Adjacent neighbor count is 1
Adjacent with neighbor 5.5.5.5
Suppress hello for 0 neighbor(s)
- R3:
R3#show ip ospf interface
Ethernet0/0 is up, line protocol is up
Internet Address 172.30.0.3/24, Area 0
Process ID 1, Router ID 3.3.3.3, Network Type BROADCAST, Cost: 100
Transmit Delay is 1 sec, State DROTHER, Priority 0
Designated Router (ID) 1.1.1.1, Interface address 172.30.0.1
No backup designated router on this network
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
oob-resync timeout 40
Hello due in 00:00:05
Supports Link-local Signaling (LLS)
Index 1/1, flood queue length 0
Next 0x0(0)/0x0(0)
Last flood scan length is 2, maximum is 4
Last flood scan time is 0 msec, maximum is 4 msec
Neighbor Count is 2, Adjacent neighbor count is 1
Adjacent with neighbor 1.1.1.1 (Designated Router)
Suppress hello for 0 neighbor(s)
Serial1/0 is up, line protocol is up
Internet Address 172.30.20.3/24, Area 20
Process ID 1, Router ID 3.3.3.3, Network Type POINT_TO_POINT, Cost: 647
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 00:00:08
Supports Link-local Signaling (LLS)
Index 1/2, 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 4.4.4.4
Suppress hello for 0 neighbor(s)
- R4:
R4#show ip ospf interface
Loopback4 is up, line protocol is up
Internet Address 10.20.3.1/24, Area 20
Process ID 1, Router ID 4.4.4.4, Network Type LOOPBACK, Cost: 1
Loopback interface is treated as a stub Host
Loopback3 is up, line protocol is up
Internet Address 10.20.2.1/24, Area 20
Process ID 1, Router ID 4.4.4.4, Network Type LOOPBACK, Cost: 1
Loopback interface is treated as a stub Host
Loopback2 is up, line protocol is up
Internet Address 10.20.1.1/24, Area 20
Process ID 1, Router ID 4.4.4.4, Network Type LOOPBACK, Cost: 1
Loopback interface is treated as a stub Host
Loopback1 is up, line protocol is up
Internet Address 10.20.0.1/24, Area 20
Process ID 1, Router ID 4.4.4.4, Network Type LOOPBACK, Cost: 1
Loopback interface is treated as a stub Host
Serial1/0 is up, line protocol is up
Internet Address 172.30.20.4/24, Area 20
Process ID 1, Router ID 4.4.4.4, Network Type POINT_TO_POINT, Cost: 647
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 00:00:05
Supports Link-local Signaling (LLS)
Index 1/1, 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 3.3.3.3
Suppress hello for 0 neighbor(s)
- R5:
R5#show ip ospf interface
Loopback1 is up, line protocol is up
Internet Address 10.10.0.1/24, Area 10
Process ID 1, Router ID 5.5.5.5, Network Type POINT_TO_POINT, Cost: 1
Transmit Delay is 1 sec, State POINT_TO_POINT,
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
oob-resync timeout 40
Supports Link-local Signaling (LLS)
Index 1/1, flood queue length 0
Next 0x0(0)/0x0(0)
Last flood scan length is 0, maximum is 0
Last flood scan time is 0 msec, maximum is 0 msec
Neighbor Count is 0, Adjacent neighbor count is 0
Suppress hello for 0 neighbor(s)
Serial1/0 is up, line protocol is up
Internet Address 172.30.10.5/24, Area 10
Process ID 1, Router ID 5.5.5.5, Network Type POINT_TO_POINT, Cost: 647
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 00:00:08
Supports Link-local Signaling (LLS)
Index 5/5, 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)
Loopback4 is up, line protocol is up
Internet Address 10.10.3.1/24, Area 10
Process ID 1, Router ID 5.5.5.5, Network Type LOOPBACK, Cost: 1
Loopback interface is treated as a stub Host
Loopback3 is up, line protocol is up
Internet Address 10.10.2.1/24, Area 10
Process ID 1, Router ID 5.5.5.5, Network Type LOOPBACK, Cost: 1
Loopback interface is treated as a stub Host
Loopback2 is up, line protocol is up
Internet Address 10.10.1.1/24, Area 10
Process ID 1, Router ID 5.5.5.5, Network Type LOOPBACK, Cost: 1
Loopback interface is treated as a stub Host
OSPF Areas Lab
GNS3 Project: File:Cbt nuggets ospf areas lab.zip
Objectives
- Configure basic OSPF:
Advertize all networks attached. On R1 redistribute static routes to inject external routes. These routes should be marked as type E1.
- R1 should never form neighbor relation on any interface where OSPF router is not connected.
- All routers in Area 0 should use MD5 auth with password cisco.
- Area 23 should use clear-text authentication.
- Routers in Area 45 are weak, should never receive external to OSPF routes(config Stub area).
These routes should reach external network using default route which cannot be statically configured.
- Routers in Area 23 should not receive Type 3,4,5 LSAs.
They should reach external network using a default route with initial OSPF cost of 100.
- You should be able to ping every router in OSPF Routing Table (configure virtual link for area 78)
Configurations
- R1 config
! interface Ethernet0/0 ip address 10.100.1.1 255.255.255.0 ip ospf authentication message-digest ip ospf message-digest-key 1 md5 cisco half-duplex ! ! router ospf 1 router-id 1.1.1.1 log-adjacency-changes redistribute static metric 50 metric-type 1 subnets passive-interface default no passive-interface Ethernet0/0 network 10.100.1.1 0.0.0.0 area 0 ! ip route 172.31.0.0 255.255.255.0 Null0 ip route 172.31.1.0 255.255.255.0 Null0 ip route 172.31.2.0 255.255.255.0 Null0 ip route 172.31.3.0 255.255.255.0 Null0 !
- R2 config
! interface Ethernet0/0 ip address 10.100.1.2 255.255.255.0 ip ospf authentication message-digest ip ospf message-digest-key 1 md5 cisco half-duplex ! interface Serial1/0 ip address 10.23.1.2 255.255.255.0 ip ospf authentication ip ospf authentication-key cisco serial restart-delay 0 ! router ospf 1 router-id 2.2.2.2 log-adjacency-changes area 23 stub no-summary area 23 default-cost 100 network 10.23.1.2 0.0.0.0 area 23 network 10.100.1.2 0.0.0.0 area 0 !
- R3 config
! interface Loopback0 ip address 172.30.0.1 255.255.255.0 ! interface Loopback1 ip address 172.30.1.1 255.255.255.0 ! interface Loopback2 ip address 172.30.2.1 255.255.255.0 ! interface Loopback3 ip address 172.30.3.1 255.255.255.0 ! ! interface Serial1/0 ip address 10.23.1.3 255.255.255.0 ip ospf authentication ip ospf authentication-key cisco serial restart-delay 0 ! ! router ospf 1 router-id 3.3.3.3 log-adjacency-changes area 23 stub network 10.23.1.3 0.0.0.0 area 23 network 172.30.0.0 0.0.255.255 area 23 !
- R4 config
! interface Ethernet0/0 ip address 10.100.1.4 255.255.255.0 ip ospf authentication message-digest ip ospf message-digest-key 1 md5 cisco half-duplex ! ! interface Serial1/0 ip address 10.45.1.4 255.255.255.0 serial restart-delay 0 ! router ospf 1 router-id 4.4.4.4 log-adjacency-changes area 45 stub network 10.45.1.4 0.0.0.0 area 45 network 10.100.1.4 0.0.0.0 area 0 !
- R5 config
! interface Serial1/0 ip address 10.45.1.5 255.255.255.0 serial restart-delay 0 ! ! router ospf 1 router-id 5.5.5.5 log-adjacency-changes area 45 stub network 10.45.1.5 0.0.0.0 area 45 !
- R6 config
! interface Ethernet0/0 ip address 10.100.1.6 255.255.255.0 ip ospf authentication message-digest ip ospf message-digest-key 1 md5 cisco half-duplex ! ! interface Serial1/0 ip address 10.67.1.6 255.255.255.0 serial restart-delay 0 ! router ospf 1 router-id 6.6.6.6 log-adjacency-changes area 67 virtual-link 7.7.7.7 network 10.67.1.6 0.0.0.0 area 67 network 10.100.1.6 0.0.0.0 area 0 !
- R7 config
! interface Serial1/0 ip address 10.67.1.7 255.255.255.0 serial restart-delay 0 ! interface Serial1/1 ip address 10.78.1.7 255.255.255.0 serial restart-delay 0 ! ! router ospf 1 router-id 7.7.7.7 log-adjacency-changes area 67 virtual-link 6.6.6.6 network 10.67.1.7 0.0.0.0 area 67 network 10.78.1.7 0.0.0.0 area 78 !
- R8 config
! interface Serial1/1 ip address 10.78.1.8 255.255.255.0 serial restart-delay 0 ! ! router ospf 1 router-id 8.8.8.8 log-adjacency-changes network 10.78.1.8 0.0.0.0 area 78 !
Command Line Outputs
References
{{#widget:DISQUS |id=networkm |uniqid=OSPF |url=https://aman.awiki.org/wiki/OSPF }}