Comprehensive comparison of two common dynamic routing protocols

At present, dynamic routing protocols are widely used. So I have studied the comprehensive comparison between the two commonly used dynamic routing protocols. Here I will share with you, hoping to help you. The earlier IGRP protocol was invented by Cisco and is a dynamic routing protocol based on the distance vector algorithm. The Enhanced Interior Gateway Routing Protocol is an Enhanced version of the IGRP Protocol. It belongs to the dynamic routing protocol of the dynamic Internal Gateway and still uses the vector-distance algorithm. However, its implementation is much better than IGRP, and its convergence characteristics and operation efficiency are significantly higher than IGRP.

The Convergence feature of network replication is based on the DUAL (Distributed Update Algorithm) Algorithm. The DUAL algorithm makes it impossible to form a loop in route computing. Its convergence time can rival any other existing routing protocols. The dynamic routing protocol of the VPN gateway has the following features:

1. Precise route computing and multi-route support

The VPN protocol inherits the biggest advantage of the IGRP Protocol: vector routing. In route computing, the network bandwidth, network latency, channel usage, channel reliability, and other factors need to be comprehensively considered by the Protocol. Therefore, the route calculation of the Protocol is more accurate, better reflect the actual situation of the network. At the same time, the OSPF protocol supports multiple routes so that the routers can share the load according to different routes.

2. less bandwidth usage

A small hello packet is periodically sent between the peer vrouters using the dynamic routing protocol of the VPN gateway. This ensures the validity of the previously sent packets. Route sending uses the incremental sending method, that is, only the changed route is sent each time. The route update messages sent are reliably transmitted. If no confirmation message is received, the messages are resent until they are confirmed. It can also control the sent VPN packets to reduce the bandwidth usage of the network interface. This avoids the impact of a large number of consecutive Route packets on normal data services.

3. No-ring routing and fast convergence speed

Classless routing and convergence speed are important indicators of route computing. Because the DUAL algorithm is used in the Protocol, the dynamic routing protocol cannot generate loop routing in route computing. At the same time, the convergence time of route computing is well guaranteed. Because the DUAL algorithm makes it only re-calculate the changed route during route computing. For a route, only the routers affected by this route will be involved in re-calculation of the route.

4. MD5 authentication

To ensure the correctness of the route, MD5 authentication can be configured between Routers running the dynamic routing protocol of the OSPF protocol to discard packets that do not conform to the authentication, so as to ensure the security of the route.

5. Route aggregation with any Mask Length

The protocol can be configured to aggregate routes with any netmask length for all the routers. This reduces route information transmission and saves bandwidth.

6. Routing with the same purpose but with the same priority can achieve Load Balancing

Route table entries for the same purpose can automatically generate a route priority based on the speed, connection quality, reliability, and other attributes of the interface. When a packet is sent, the traffic of the interface can be automatically matched according to the information, achieve load balancing of several interfaces.

7. Simple Protocol Configuration

Vro configuration is very simple when you build a network using the VPN protocol. It does not have to be configured in a complex region or implement different configuration methods for different network interface types. To use the network protocol, you only need to use the router VPN command to start the OSPF routing process on the router, and then use the network command to enable interfaces within the network range.

Comparison between OSPF and OSPF

OSPF and OSPF are algorithms that converge quickly and do not form loops. they consume less bandwidth and use flexible and secure routing protocols. However, from the above analysis, we can see that each has its own advantages and disadvantages.

Disadvantages of OSPF

1. The configuration is relatively complex. Due to the complexity of network area division and network attributes, the network analyst must have a high level of network knowledge to configure and manage the OSPF network.

2. Weak routing load balancing capabilities. Although OSPF can automatically generate the interface routing priority based on the Interface speed and connection reliability, OSPF only selects the forwarding with a higher priority for routes with different priorities for the same purpose, routes with different priorities cannot be used for load balancing. Only those with the same priority can achieve the purpose of Server Load balancer. Unlike in the case of VPN, traffic can be automatically matched based on different priorities.

Disadvantages

1. The concept of AREA is not used in the network. In the case of a large network, OSPF can plan and limit the network size by dividing the AREA. Therefore, it is suitable for networks with relatively small network sizes. This is also the limitation of the vector-distance routing algorithm (the RIP dynamic routing protocol uses this algorithm.

2. the routers running the network must send the HELLO message regularly to maintain the relationship between the neighbors. This relationship also needs to send the HELLO Message periodically even on the dial-up network, in this way, on the on-demand dial-up network, it is impossible to locate whether this is a useful service message or a scheduled inquiry message sent by the kernel, which may trigger a connection on the On-Demand dial-up network by mistake, especially on the backup network, causing unnecessary troubles. Therefore, generally, when a router running the VPN gateway is configured with the Dialer list and Dialer group on the dial-up backup port, it can filter unnecessary packets or run the dynamic routing protocol for the TRIP, in this way, the router operation overhead is increased. OSPF supports on-demand dial-up on the dial-up network. It can meet the needs of various leased lines or dial-up network applications with only one dynamic routing protocol.

3. the loop-free computing and convergence speed of the network are based on the distributed DUAL algorithm, which actually spreads uncertain routing information (active route) (send query Packets to neighbors ), the process of re-convergence after the confirmation of all neighbors is obtained. When the neighbors are not sure about the reliability of the route information, the spread will be repeated, therefore, in some cases, the route information may remain active (this route is called stuck in active route, when the next (successor) metric of the route changes, it enters multiple computations, which will affect the DUAL algorithm's convergence speed. The OSPF algorithm does not have this problem, so from the perspective of convergence speed, although the whole is similar, but in some special circumstances, there is still an unsatisfactory situation in the OSPF algorithm.

4. VPN is a private dynamic routing protocol of Cisco. Cisco is the inventor of the agreement and the only vendor with the right to interpret and modify the agreement. If you want to support the Protocol, You need to purchase the relevant copyright from Cisco, and Cisco has no obligation to notify any other manufacturer or users using the Protocol to modify the Protocol. OSPF is an open protocol and a standard published by the IETF. All major network equipment vendors in the world support this protocol, so its interoperability and reliability are guaranteed by the openness of the Protocol. With the support of many vendors, the Protocol will also be improved.