Skip to main content

Troubleshooting routing issues

Troubleshooting routing issues 
9.3.5 This page will describe the show ip protocols and show ip route commands. These commands display information about routing protocols and the routing table. The output from these commands can be used to verify the routing protocol configuration.
The show ip route command may be the most important command used to troubleshoot routing issues. This command displays the contents of the IP routing table. The output from the show ip route command shows the entries for all known networks and subnetworks, and how that information was learned. 
If there is a problem reaching a host in a particular network, then the output of the show ip route command can be used to verify that the router has a route to that network.
If the output of the show ip route command does not show the expected learned routes, or any learned routes, then the problem may be that routing information has not been exchanged. In this case, use the show ip protocols command on the router to check for a routing protocol configuration error.
The show ip protocols command displays values about IP routing protocol information on the entire router. This command can be used to confirm which protocols are configured, which networks are being advertised, which interfaces are sending updates, and the sources of routing updates. The show ip protocols output also shows timers, filters, route summarization, route redistribution, and other parameters that are specific to each routing protocol that is enabled on the router. When multiple routing protocols are configured, the information about each protocol is listed in a separate section. 
The show ip protocols command output can be used to diagnose many routing issues. For example, it can be used to identify a router that may advertise incorrect routing information. This command may be used to confirm that expected protocols, advertised networks, and routing neighbors are present. It is important to have documentation that indicates the expected results, or baseline information, when a problem occurs. It may be impossible to identify the problem without such documentation.
The Lab Activity will teach students how to use the show ip route and show ip protocols command.
The next page will discuss the show controllers serial command.

Comments

Post a Comment

Popular posts from this blog

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...
Post a Comment
Read more

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...
Post a Comment
Read more

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...
Post a Comment
Read more