Ip routing what is

Any data sent to, or received from, a destination outside the AS must travel over that connection. A small campus network is an example of a stub AS. A Transit AS has multiple connections to one or more ASs, which permits data that is not destined for a node within that AS to travel through it. A Multihomed AS also has multiple connections to one or more ASs, but it does not permit data received over one of these connections to be forwarded out of the AS again.

In other words, it does not provide a transit service to other ASs. A Multihomed AS is similar to a Stub AS, except that the ingress and egress points for data traveling to or from the AS can be chosen from one of a number of connections, depending on which connection offers the shortest route to the eventual destination. A large enterprise network would normally be a multihomed AS. Networks in the internet are connected to each other via routers.

Routers maintain a routing table to decide how to route the IP packets. Each routing entry consists of the destination address, subnet mask and "route to" field. When a message needs to be routed to an IP address, the following steps are followed:. Note: IP routing also supports a default entry. If the packet does not match any other entry, it is routed according to the default entry. Another important aspect of internets is a node in the internet can have multiple IP addresses.

There will be one IP address per interface. For example, the Router in the figure above has three IP addresses, viz. IP Address Classification IP addresses are 32 bit integers which are represented in the familiar dot based notation.

An Example Internet Subnets The figure below describes a small internet consisting of three networks IP Routing Networks in the internet are connected to each other via routers.

When a message needs to be routed to an IP address, the following steps are followed: The destination IP address is masked with the subnet mask and then compared with the destination field for all entries in the routing table.

This comparison may yield a match with more than one entry the entry with the longest subnet mask will be selected. The entry corresponding to Once an entry has been selected, the "route to" field is consulted and the action taken depends on the contents of this field: If the "route to" field contains SELF the packet is meant for this node.

In this case, the packet is routed directly on the LAN. If the "route to" field contains an IP address, the packet is forwarded to the IP address specified. Further routing of the packet will be carried out by the specified IP address.

But the purpose stays the same; efficient communication between networks. Your email address will not be published. Notify me of followup comments via e-mail. You can also subscribe without commenting. This site uses Akismet to reduce spam.

Learn how your comment data is processed. RouterFreak is a blog dedicated to professional network engineers. Configuration Tips , Network Fundamentals , Routing. Andreas Grant. Share on facebook. Share on twitter. Share on linkedin.

Share on whatsapp. Share on telegram. This article explains what IP routing is and how it works as clearly as possible. Table of Contents. He has many years of experience working in network management and cybersecurity. Andreas is passionate about technology and blogging and enjoys teaching what he knows to anyone interested.

What do you think about this article? Leave a Reply Cancel reply Your email address will not be published. About us. Popular articles. Unimus review: Network Automation and Configuration Management.