Figure 9: Adding a new RIP interface. Figure Configuring the new RIP interface. Before I conclude this section about RIP in Windows, I want to point you to a couple of excellent resources I used while preparing for this article:.
Windows Server has one solid static routing option and one scalable dynamic routing option — RIPV2. We talked about why you would use static routing versus dynamic routing. Your email address will not be published. Learn about the latest security threats, system optimization tricks, and the hottest new technologies in the industry. Over 1,, fellow IT Pros are already on-board, don't be left out!
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The router then determines the best route to take and forwards the packets to that route. The packet then goes to the next router and the entire process repeats itself until it gets to the destination LAN. The destination router then forwards the packets to the destination computer. To determine the best route, the routes use complex routing algorithms, which take into account a variety of factors, including the speed of each transmission media, the number of network segments, and the network segment that carries the least traffic.
Routers then share status and routing information to other routers so that they can provide better traffic management and bypass slow connections.
In addition, routers provide additional functionality, such as the capability to filter messages and forward them to different places based on various criteria. Most routers are multiprotocol routers because they can route data packets using many different protocols. A metric is a standard of measurement, such as hop count, that is used by routing algorithms to determine the optimal path to a destination.
A hop is the trip a data packet takes from one router to another router or from a router to another intermediate point to another in the network. On a large network, the number of hops a packet has taken toward its destination is called the hop count.
When a computer communicates with another computer, and the computer has to go through four routers, it has a hop count of four. With no other factors taken into account, a metric of four would be assigned.
If a router had a choice between a route with four metrics and a route with six metrics, it would choose the route with four metrics over the route with six metrics. Of course, if you want the router to choose the route with six metrics, you can overwrite the metric for the route with four hops in the routing table to a higher value.
To keep track of the various routes in a network, routers create and maintain routing tables. Routers communicate with one another to maintain their routing tables through a routing update message. The routing update message can consist of all or a portion of a routing table.
By analyzing routing updates from all other routers, a router can build a detailed picture of network topology. Static routing algorithms are hardly algorithms at all, but are table mappings established by the network administrator prior to the beginning of routing.
These mappings do not change unless the network administrator alters them. Algorithms that use static routes are simple to design and work well in environments where network traffic is relatively predictable and where network design is relatively simple. Most of the dominant routing algorithms are dynamic routing algorithms , which adjust to changing network circumstances by analyzing incoming routing update messages.
If the message indicates that a network change has occurred, the routing software recalculates routes and sends out new routing update messages. These messages flow through the network, stimulating routers to rerun their algorithms and change their routing tables accordingly. Routers use distance-vector—based routing protocols to periodically advertise or broadcast the routes in their routing tables, but they send it to only their neighboring routers.
Routing information exchanged between typical distance-vector—based routers is unsynchronized and unacknowledged. Distance-vector—based routing protocols are simple and easy to understand and easy to configure. The disadvantage is that multiple routes to a given network can reflect multiple entries in the routing table, which leads to a large routing table.
In addition, if you have a large routing table, network traffic increases as it periodically advertises the routing table to the other routers, even after the network has converged.
Last, distance-vector protocol convergence of large internetworks can take several minutes. Link-state algorithms are also known as shortest path first algorithms. Instead of using broadcast, link-state routers send updates directly or by using multicast traffic to all routers within the network. Each router, however, sends only the portion of the routing table that describes the state of its own links.
In essence, link-state algorithms send small updates everywhere. Because they converge more quickly, link-state algorithms are somewhat less prone to routing loops than distance-vector algorithms. In addition, link-state algorithms do not exchange any routing information when the internetwork has converged.
They have small routing tables because they store a single optimal route for each network ID. On the other hand, link-state algorithms require more CPU power and memory than distance-vector algorithms. Link-state algorithms, therefore, can be more expensive to implement and support and are considered harder to understand. A popular routing protocol is the Routing Information Protocol RIP , which is a distance-vector protocol designed for exchanging routing information within a small- to medium-size network.
The biggest advantage of RIP is that it is extremely simple to configure and deploy. RIP uses a single routing metric of hop counts number of routers to measure the distance between the source and a destination network.
Each hop in a path from source to destination is assigned a hop-count value, which is typically 1. When a router receives a routing update that contains a new or changed destination network entry, the router adds one to the metric value indicated in the update and enters the network in the routing table. Because RIP uses only hop count to determine the best path to an internetwork. If RIP finds more than one link to the same remote network with the same hop count, it automatically performs a round-robin load balance.
RIP can perform load balancing for up to six equal-cost links. However, a problem with using hops as the only metric is when two links to a remote network have different bandwidths. For example, if you have one link that is a 56KB switched link and a T1 running at 1.
This is known as pinhole congestion. To overcome pinhole congestion, you have to design a network with equal bandwidth links or use a routing protocol that takes bandwidth into account. RIP prevents routing loops from continuing indefinitely by implementing a limit on the number of hops allowed in a path from the source to a destination. The maximum number of hops in a path is If a router receives a routing update that contains a new or changed entry, and if increasing the metric value by one causes the metric to be infinity in this case, 16 , the network destination is considered unreachable.
Of course, this makes it impossible for RIP to scale to large or very large internetworks. Note: The count-to-infinity problem is the reason why the maximum hop count of RIP for IP internetworks is set to 15 16 for unreachable. Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support.
Displays and modifies the entries in the local IP routing table. Used without parameters, route displays help. For examples of how this command can be used, see Examples. Clears the routing table of all entries that are not host routes routes with a netmask of If this is used in conjunction with one of the commands such as add, change, or delete , the table is cleared prior to running the command.
When used with the print command, the list of persistent routes is displayed. This parameter is ignored for all other commands.
Specifies the network destination of the route. The destination can be an IP network address where the host bits of the network address are set to 0 , an IP address for a host route, or 0. Specifies the forwarding or next hop IP address over which the set of addresses defined by the network destination and subnet mask are reachable. For locally attached subnet routes, the gateway address is the IP address assigned to the interface that is attached to the subnet.
For remote routes, available across one or more routers, the gateway address is a directly reachable IP address that is assigned to a neighboring router.
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