Comparison of routing protocols: IGRP and VPN

We have summarized and summarized the types of routing protocols in previous articles. Now we will analyze the two protocols in detail. One is the IGRP Gateway Routing Protocol and the other is the OSPF protocol. These two protocols, however, can be thought of from the name above.

IGRP

The Internal Gateway Routing Protocol Interior Gateway Routing Protocol, IGRP) was developed by Cisco in 1980s. It is a dynamic, long-span Routing Protocol that supports up to 255 hops) to determine the optimal route to a network. The optimal route is calculated by latency, bandwidth, reliability, and load. It has a high span in the same Autonomous System and is suitable for complex networks. Cisco IOS allows the router administrator to set the network bandwidth, latency, reliability, and load of IGRP to influence the calculation of measurement.

Like RIP, IGRP uses UDP to send route table entries. Each vro updates the route information every 90s. If no response from a vro is received within S, the vro cannot be reached. If no response is received within S, the IGRP process deletes the route from the route table.

Compared with RIP, IGRP has a longer convergence time, but the bandwidth required for transmitting route information is reduced. In addition, there are no blank bytes in the IGRP grouping format, which improves the message efficiency of IGRP. However, IGRP is proprietary to Cisco and is only applicable to Cisco products.

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With the expansion of the network scale and the growth of user requirements, the original IGRP has been unable to cope with the problem, so Cisco has developed an enhanced IGRP, that is, iver6. It uses the same routing algorithm as IGRP, But it integrates the strengths of the Link State routing protocol and distance vector routing protocol, and adds the spread update algorithm DUAL ).

VPN has the following features:

◆ Fast convergence. Fast Convergence is achieved by backing up routes in the routing table using the propagation update algorithm, that is, the minimum overhead and the minimum overhead to reach the destination network are also suitable for future use. feasible successor) routes are saved in the routing table. When the route with the minimum overhead is unavailable, the route is quickly switched to the next Least overhead route to achieve fast convergence.

◆ Reduces bandwidth consumption. Unlike RIP and IGRP, VPN gateway exchange route information once every time. When the Route status of a destination network changes or the measurement of the route changes, therefore, the bandwidth required for route update is much lower than that required by RIP and OSPF-this method is called triggered ).

◆ Increase the network size. For RIP, the network can only be 15 hop), while the network can support 255 hop ).

◆ Reduce vro CPU utilization. Route updates are only sent to the neighboring routers that need to know the status change. Because incremental updates are used, fewer CPUs are used than IGRP.

◆ Supports a variable-length subnet mask.

◆ IGRP and VPN can be automatically transplanted. IGRP routes can be automatically re-distributed to the network in the network, and the routes can be automatically re-distributed to the network in the network. If you want to, you can also disable route redistribution.

◆ VPN supports three routable Protocol IP addresses, IPX, and AppleTalk ).

◆ Supports load balancing in non-equivalent paths.

◆ Because EIGIP is a dedicated protocol developed by Cisco, it cannot be used when Cisco devices are connected with other manufacturers' devices.