Before going to study routing metric value, we should have a clear idea about what is metric and metric value. The main purpose of using metrics is to identify the cost of a route that we are using. In simple it(metric value) can be defined as: It is a value and this value is assigned to a particular network’s IP route. For example, there are different things that can be valued as a metric value, includes the following:
⦁ hop count.
⦁ link speed.
⦁ time delay.
There is another feature in Windows to automatically configure the metric value. This new feature of windows can be used only for the local route. This automatic configuration is based on one of the above-mentioned point called, link speed. The two important advantages of using automatic metric values are:
- If we want to assign a specific metric can configure it manually.
- It is enabled by default.
If the routing table has many routes to a single destination, the automatic metric can be used.
The importance of route metric value is explained in the following sentence. As we explained above, if there are a number of routes are identified by using multiple routing protocols to route the packets, to the same destination by a router, one method for choosing the best route is by using the administrative distance by the router.
But in some situations, the same protocol may choose two different routes to route the packets to the same destination. In such situations, the optimal way to find the best route is by using the Route Metric Value.
Calculation of Route Metric Value
- Calculating route metric value by RIP(Routing Information Protocol) protocol:
Here in this protocol, the metric is the hop count. Where, the term hop court can be defined as, “It is the total number of routers data that are transferred in the path while transferring the packets from source to destination”. It does not depend on other factors such as delay, bandwidth, etc. Here, the best path can be found out by analyzing the hop count value, the path which has the minimum hop count would be the best path.
- Calculating route metric value by EIGRP(Enhanced Interior Gateway Routing Protocol.):
Here in this protocol, unless RIP, to find the route metric values find out by using complex equations.
Unlike RIP it uses some features such as :
- Load, to identify the best optimal path.
Even if the Path has a greater hop count, it does not care.
- Calculating route metric value by OSPF(Open Shortest Path First):
Another name of the metric value of the OSPF protocol is OSPF Cost Value. This value can be calculated and is equal to the accumulated cost value while we routing packets from source to destination.
The costs and bandwidth of interfaces are very related. That is when the interface has greater bandwidth, then its cost will be less. If it has less bandwidth, then the interface will have a larger cost. In simple, we can say that both of them are inversely proportioned to each other.
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