Three criteria of the Routing Protocol

A routing protocol is a protocol that is measured in network protocols. The standard of the routing protocol often affects the performance of the entire network, especially in the IPv6 network. Now let's take a look at the main content of the article.

Stability

The routing protocol must be stable to prevent routing loop problems. A routing loop is caused by a false route information broadcast immediately after the network topology changes, which can cause the network to crash. RIP and other less advanced protocols use the persistence timer holddown timer) to improve stability. If the performance of a subnet declines, all routers will ignore any updates to that subnet while the timer is running.

This routing protocol effectively adopts a "wait-and-see" method after the network topology structure changes to ensure the network stability. However, because the RIP Protocol does not maintain sufficient information to quickly and reliably converge the network, the disadvantage of using the timer is to reduce the aggregation speed. This is a last resort.

Aggregation speed

When the network topology changes, such as losing or adding a subnet, each vro on the network knows that this change has a delay. During this interval, some routers run according to inconsistent information. Therefore, the aggregation time can also be considered as the time interval from when the network topology changes to when all the routers in the network know the consistent information related to the affected subnet.

The convergence speed of a network varies depending on many factors. These factors have nothing to do with the operating characteristics of the routing protocol itself. OSPF and other advanced link status routing protocols maintain the link status database of all subnets in a network, detailing what routers are connected to these subnets. If a link fails, the router directly connected to the link will immediately send a link status announcement LSA to the neighboring router. This announcement will be sent to the entire network. After receiving the LSA information, each router queries its database and independently recalculates the route table after the network topology changes.

Because OSPF stores more extensive network topology information than the route table, the aggregation speed is fast and reliable. This is different from RIP and other simple protocols. As previously discussed, these simple protocols require that the timer be maintained after the network topology structure changes to ensure that no loops converge.

Measurement criteria

A router that knows multiple paths to a specific target network through the Routing Protocol) will select the path with the best measurement index and location in the routing table. If there are more than one Optimal measurement path, each path in these low-price paths will be placed in the routing table and the equivalent load balancing test will be conducted.

Different routing protocols use different standards. In other words, each of the various routing protocols has its own method to select the best path to the destination. This measure should be very advanced to ensure that the routing protocol can be used to explain the optimal path. The RIP protocol uses the Skip count as its metric. This is another restriction on this specific routing protocol. For example, if a vro has two paths leading to one destination, one path is a 56 K line, and the other path is a T-1 line, if the number of hops on the vro is the same, the RIP Protocol considers these two paths to be equivalent. Therefore, the RIP Protocol performs load balancing, although one path is 23 times faster than the other.

The OSPF protocol uses management costs as a measure. This standard can be set forcibly. In a Cisco router, this measurement standard is automatically calculated and is inversely proportional to the bandwidth of the link. The Nortel Network uses an alternative method to ensure OSPF equivalence by setting default values on all links.