Shulou(Shulou.com)06/01 Report--

Theoretical study

Question 1: describe the operation of link-state protocols based on OSPF?

Each router sends its own connected link data to neighboring routers, and the routers exchange link state information with each other to form a complete network topology, so that all routers have a complete topology of the whole network.

Question 2: what is the difference between neighbors and adjacencies?

Neighboring routers can directly transmit LSA information, while neighboring routers cannot directly exchange LSA information,

Question 3: describe the working process of OSPF?

OSPF routing protocol is a typical link-state routing protocol. By sending link-state packet LSA to a router in a certain area, Dijikstra algorithm is used to calculate and update the routing table.

(1) all routers exchange HELLO packets (every 10s), and the destination address is 224.0.0.5, resulting in DR and BDR, forming neighbor / adjacency.

(2) next, the link-state database (LSDB) synchronization is carried out by exchanging LSA between DR and DROTHER, and the data LSDB of each router updates its routing table.

(3) if there is an emergency that requires routing updates (such as link failure), the DROTHER router sends the new LSA to the DR through the 224.0.0.6 multicast address, and then the dr sends it to the entire network through 224.0.0.5.

(4) every 1800 seconds, all routers flood lsa into the whole network through 224.0.0.5 multicast address, and complete update to achieve the synchronization of all link information.

(5) if DR fails, BDR will take over the work.

How should the question 4:OSPF area be set?

OSPF can be divided into one or more areas, one of which should be the backbone area, which is the core of the communication of the whole network, and can also be divided into branch areas. usually the score area is connected to the backbone area (except the virtual circuit area). The operation of the OSPF is directly related to the early planning of the network, and the backbone area is usually located in the center of the network.

(1) basic orders

Router (config) # router ospf process number

Router (config-router) # network Network (Subnet) address wildcard area area number

(2) optional command

Router (config-if) # IP ospf network broadcast / non-broadcast / point-to-multipoint / point-to-point

Router (config-router) # neighbor

Router (config-router) # router-id

(3) Test command

Router# show IP route

Router#show IP Protocol

Router#show IP ospf neighbor

Router#show IP ospf datebase

Router#show IP ospf interface

Router#debug IP ospf

Job task description

Companies An and B both have their own independent local area networks and connect with CNC routers respectively (three routers are connected to four subnets), requiring the use of RIP dynamic routing to implement the project.

Task implementation

1. Network topology design

two。 Device configuration commands (each router is configured separately)

R1 router configuration

CNC router configuration

R2 router configuration

Configure computer A

Configure computer B

Configure R1 with ospf

Configure ospf for CNC

Configure R1 with ospf

3. Single-stage test results

Computer ping router f0pic0 interface

R1 router ping CNC router f0bin0

CNC Router ping R2 Router f0bin0

Computer ping R2 Router f0Compact 1

4. Comprehensive test results

A ping B

5. View routes for each router

View R1 routing information,

View CNC routing information,

View R2 routing information

6. View information about OSPF.

View R1 routes,

View ospf neighbor information

View CNC routes,

View R2 rout

Work expansion

Requirements for specifications and coordination of OSPF multi-area networks

(1) Topology diagram

(2) main configuration commands for each router

RA main configuration file:

R1 main configuration files:

CNC main configuration file:

The main configuration file for R2:

The main configuration of RB:

(3) analyze the routing of each router

RA routing configuration

R1 routing configuration:

CNC routing configuration:

R2 routing configuration:

RB routing configuration:

Think about the question:

Question 1: compare the similarities and differences between OSPF and RIP?

(1) the only parameter for RIP routing to identify the distance of the destination network is the hop count, which is limited to a maximum of 15, so RIP is suitable for routing communication in small and medium-sized networks. For OSPF routing protocol, the parameter indicating the distance in the routing table is coat, which is related to the bandwidth of the links in the network, that is to say, OSPF routing information is not physically limited, so it is suitable for large and medium-sized networks.

(2) RIPv1 routing protocol does not support variable length subnet mask (VLSM), and RIPv2 supports VLSM. OSPF also supports VLSM, which can save ip addresses to the maximum extent.

(3) the RIP routing protocol periodically broadcasts the whole routing table as routing information to the network, the broadcast period is 30 seconds, and the route convergence is slow, while OSPF is a link-state protocol, which uses the combination of periodic and trigger update mode, the periodic update time is 1800 seconds, the route information in the network is less, and the route convergence is slow.

(4) in RIP routing protocol, network is a flat concept, and there is no definition of area and boundary. In OSPF routing protocol, a network, or a routing domain, can be divided into many areas, each of which is connected by an OSPF border router. The routing information can be reduced by route summarization to achieve the purpose of reducing the routing table to improve the routing speed.

(5) in the RIP routing protocol, there is only one table, that is, the routing table, and the routing update is the direct exchange update of the routing table. In OSPF, there are three tables, namely, neighbor table, link state table and routing table. Routing updates are announced through LSA.

(6) RIPv1 carries out routing updates by broadcast, while RIPv2 uses multicast, and the multicast address is 224.0.0.9. OSPF also uses 224.0.0.5 and 224.0.0.6 multicast addresses for routing updates.

(7) RIPv1 does not support route verification, while ripv2 supports route verification with plaintext and MD5 encryption. The OSPF routing protocol also supports plaintext and MD5 encrypted routing verification, and OSPF can define different authentication methods for different areas to improve the security of the network.

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