Cisco Learning Note CCNP-OSPF

OSPF Three Sheets

Neighbors

Topology is LSDB.

Routing table

OSPF uses a hierarchical architecture (this two-level hierarchy consists of the following)

-transit area (backbone or area 0)

-regular areas (non backbone area)

OSPF Area Characteristics:

Minimizes routing table entries

localizes impact of a topology change within an area

Detailed LSA flooding stops at the area boundary (LSA: Link status advertisement)

Requires a hierarchical network design

Types of routers in OSPF

Backbone router, ABR router (satisfies the condition that an interface must be area 0) ASBR (border router)

Point-to-Point

--both Neighbors become fully adjacent

Lan Links:

--neighbors form a full adjacency with the DR and BDR

--routers maintain two-way state with the other routers (drothers) ( router maintains bidirectional status with other routers)

Routing Updates and topology information is passed only between adjacent routers

Routing information can be passed in an adjacency state

Once an adjacency is Formed,lsdbs be synchronized by exchanging LSAs

LSAs is flooded reliably throughout the area (or network)

Hello packets exchanged via IP multicast

Electing DR and BDR (selection method of selected DR&BDR)

Highest OSPF Priority

Highest Router ID

OSPF Router-id Elections:

Manual designation

Loopback address Max (active)

Maximum physical interface address (active)

Rid does not preempt

Router restart

Process restart clear IP OSPF process

Dr Election rules:

Do not preempt

30s election time

than time

than the priority level

Highest than RID

When Dr fails, BDR becomes DR, electing a new BDR

Choose BDR First and select Dr

Neighbor Neighbors 2way

Adjacency adjacency Full

Adjacencies must be neighbors, neighbors may not necessarily be contiguous

10^8/bandwidth to automatically confirm link cost

30-minute Update Lsdb

Hello router Id,hello and dead interval *,neighbors,area id*,router priority,dr IP address,bdr IP address, authencation p Assword *, stub area flag*

Dbd

Lsr

LSU

Lsaack

Version: Release number v2 (IPv4) v3 IPv6

Authentication type:

0 NULL Authentication

1 Clear authentication

2 redaction Certification

The Hello time for Ethernet is 10s dead 40s

Wan Hello time is 30s dead 120s

OSPF Network type:

1.Point to point serial FR subinterface (Frame Relay) ATM

2.broadcast Ethernet Token Ring (Token ring)

3.NBMA X. FR

4.P2MP point to multipoint.

5.P2MP NBMA Point-to-multipoint non-broadcast multi-channel access

6.loopbcak

#show IP OS int s 0/0 view OSPF interface network type

Network type Interface Hello whether the election dr,bdr whether multicast establishes neighbor

Peer Serial 10s not selected Yes

FR subinterface

Broadcast Ethernet Token Ring 10s Select Yes

NBMA 30s selected (neighbors)

P2MP 30s not selected Yes

P2MP NBMA 30s not selected

Loopback (cannot be modified by command to Loopbak)

The peer subnet mask can be different

Other types of subnet masks must be the same

Attempt in Frame Relay environment

Neighbors

Specify R1 to become Dr,ip OS priority 0 Precedence 0 Do not participate in DR, BDR elections

Link-state Advertisement

LSA Type Description

Router LSAs

Network LSAs

3or 4 Summary LSAs

5 Autonomous System

External LSAs

6 Multicast OSPF LSA

7 Defined for Not-so-stubby areas

8 External attributes LSA for border

Gateway Protocol (BGP)

9,10,11 Opaque LSAs

show ip os border-routers---------------------------------------? see who is ABR

show ip OS database asbr-----------------------------------------? view LSA 4

First Class LSA

Origin: Each route has 1 types of LSA

Spread: Spread in the region, not through the ABR

Content:

OSPF Rollup:

Interregional summary

Configured on all ABR in the rollup area, Zone 0 range 192.168.0.0 255.255.0.0

As Inter-summary:

Configured on ASBR, summary-address 10.1.0.0 255.255.252.0 tag 88

Filter

Why to play tag, to support QoS, it is necessary to use QoS, convenient, tag is not used alone.

Tunnel

Virtual link

OSPF Multi-process

1 Interface Tunnel 0

Ip Address 31.1.1.1 255.255.255.0

Ip OSPF 1 Area 0

Tunel Source 1.1.1.1.

Tunnel Destination 3.3.3.3

Router OSPF 1

Router-id 3.3.3.3

Redistribute OSPF 2 subnets

Router OSPF 2

Router-id 33.3.3.3

Redistribute OSPF 1 subnets

Area 1 Virtual-link 3.3.3.3 (each other's Router-id) zone ID is the region

Virtual-link has donotage (DNA) aging properties.

OSPF authentication:

Authentication Type / Way	Clear Certification	Ciphertext authentication
Interface authentication:	Interface Serial 0/1 Ip OSPF authentication Ip OSPF Authentication-key 123123	Interface Serial 0/1 Ip OSPF authentication Message-digest Ip OSPF authentication Message-key 1 MD5 12345
Regional certification:	Router OSPF 1 Area 0 Authencation Interface Serial 0/1 Ip OSPF Authencation-key 123	Router OSPF Area 0 Authentication Message-digest Interface Serial 0/1 Ip OSPF message-digest key 1 MD5 123123
Virtual link Authentication :	Router OSPF Area 1 Virtual-link 1.1.1.1 authentication Authencation-key 123123	Router OSPF 1 Area 1 Virtual-link 1.1.1.1 authencation message-digest Area 1 Virtual-link 1.1.1.1 Message-digest-key 1 MD5 Cisco

When the authentication type is the same, the ciphertext takes precedence over the plaintext.

Zone certification and interface authentication who is the first priority?

Zone 0 is certified and virtual link is validated with zone 0 synchronization

Cisco Learning Note CCNP-OSPF