Common OSPF configuration issues

Common OSPF configuration issues
2.3.7

This page will discuss some configuration issues that could prevent communications between OSPF routers.
An OSPF router must establish a neighbor or adjacency relationship with another OSPF router to exchange routing information. Failure to establish a neighbor relationship is caused by any of the following reasons:

Hellos are not sent from both neighbors.
Hello and dead interval timers are not the same.
Interfaces are on different network types.
Authentication passwords or keys are different.

In OSPF routing it is also important to ensure the following:

All interfaces have the correct addresses and subnet mask.
network area statements have the correct wildcard masks.
network area statements put interfaces into the correct area.

The next page will discuss some show commands.

Verifying the OSPF configuration
2.3.8

This page will explain how show commands can be used to troubleshoot OSPF.
To verify the OSPF configuration a number of show commands are available. Figure

lists these commands. Figure

shows commands useful for troubleshooting OSPF.
This page concludes this lesson. The next page will summarize the main points from this module.

Comments

Windowing

Windowing 11.1.5 This page will explain how windows are used to transmit data. Data packets must be delivered to the recipient in the same order in which they were transmitted to have a reliable, connection-oriented data transfer. The protocol fails if any data packets are lost, damaged, duplicated, or received in a different order. An easy solution is to have a recipient acknowledge the receipt of each packet before the next packet is sent. If a sender had to wait for an ACK after each packet was sent, throughput would be low. Therefore, most connection-oriented, reliable protocols allow multiple packets to be sent before an ACK is received. The time interval after the sender transmits a data packet and before the sender processes any ACKs is used to transmit more data. The number of data packets the sender can transmit before it receives an ACK is known as the window size, or window. TCP uses expectational ACKs. This means that the ACK number refers to the next packet that is...

OSI layers / Peer-to-peer communications / TCP/IP model

OSI layers 2.3.4 This page discusses the seven layers of the OSI model. The OSI reference model is a framework that is used to understand how information travels throughout a network. The OSI reference model explains how packets travel through the various layers to another device on a network, even if the sender and destination have different types of network media. In the OSI reference model, there are seven numbered layers, each of which illustrates a particular network function. - Dividing the network into seven layers provides the following advantages: • It breaks network communication into smaller, more manageable parts. • It standardizes network components to allow multiple vendor development and support. • It allows different types of network hardware and software to communicate with each other. • It prevents changes in one layer from affecting other layers. • It divides network communication into smaller parts to make learning it easier to understand. In the foll...

1.2.2 RIP V2 Features

1.2.2 RIP V2 Features This page will discuss RIP v2, which is an improved version of RIP v1. Both versions of RIP share the following features: It is a distance vector protocol that uses a hop count metric. It uses hold down timers to prevent routing loops – default is 180 seconds. It uses split horizon to prevent routing loops. It uses 16 hops as a metric for infinite distance. RIP v2 provides prefix routing, which allows it to send out subnet mask information with the route update. Therefore, RIP v2 supports the use of classless routing in which different subnets within the same network can use different subnet masks, as in VLSM. RIP v2 provides for authentication in its updates. A set of keys can be used on an interface as an authentication check. RIP v2 allows for a choice of the type of authentication to be used in RIP v2 packets. The choice can be either clear text or Message-Digest 5 (MD5) encryption. Clear text is the default. MD5 can be used t...

CCNA :) Be a Good Network Administrator

Search This Blog