Router Information Protocol-detailed description of rip

The RIP Protocol is a type of routing protocol. It has been applied in many places. For the network architecture, the routing information protocol (RIP) is an internal mechanism in our network, mainly for managing network management and routing. The RIP Protocol is also required for data distribution and transmission between different protocols. Now we have come to understand every aspect of this agreement in detail.

I. background

The route information protocol (RIP) uses the number of hops as the distance vector protocol of metric. RIP is widely used in global Internet routing. It is an internal gateway protocol that implements routing functions within the autonomous system. External gateway protocol (such as edge gateway protocol BGP) is used for routing between different Autonomous Systems. The predecessor of RIP is the Xerox protocol GWINFO. Later versions of routed were pronounced as/rutdi/) encapsulated in the Berkeley standard release Unix (BSD) in 1982 ). RIP itself has evolved into an Internet routing protocol. Some protocol families use RIP variants, such as the AppleTalk route table maintenance protocol RTMP) and the Banyan VINES route table protocol RIP. The latest enhanced version of RIP is the RIP2 specification, which allows more information to be contained in the RIP group and provides a simple authentication mechanism.

Ip rip is formally defined in two documents: RFC 1058 and 1723. RFC 1058 (1988) describes the implementation of the first version of RIP. RFC 1723 (1994) is an update of RIP, allowing the RIP group to carry more information and security features.

This article briefly introduces the basic capabilities and features of RIP, including route update process, route information protocol (RIP) Route metric, route stability and timer.

Ii. route update

RIP sends route update information at the regular interval and when the network topology changes. When a vro receives an Update route entry that contains a table entry, it updates its route table. The value of metric for this path is added with 1, and the sender is recorded as the next hop. The RIP Router only maintains the path with the minimum metric value in the destination Optimal Path ). After updating the route table, the router immediately sends a route update notification to other routers, which is irrelevant to the periodically sent update information.

Iii. RIP route metric

RIP uses a single route metric hop count) to measure the distance from the source network to the target network. Each hop in the path from the source to the destination is assigned a hop value, which is usually 1. When the router receives the route update information that contains the new or changed destination network table items, it adds the metric value to 1 and saves it to the route table. the IP address of the sender acts as the next hop address.

RIP restricts the maximum number of hops from the source to the target to prevent routing loops. The maximum value is 15. If the vro receives the route update information containing the new or changed table items and adds the metric value to 1 to become an infinite number (16), the target network cannot be reached.

Iv. Stability of the routing information protocol (RIP)

To adapt to fast network topology changes, RIP defines the same stability characteristics as other routing protocols. For example, RIP implements the split-horizon and hold-down mechanisms to prevent route information from being transmitted incorrectly. In addition, the limit on the number of hops of the route information protocol (RIP) also prevents the infinite growth of the routing ring.

5. Route information protocol (RIP) Timer

RIP uses timers to control its performance, including the route update timer, route timeout, and route clearing timer. The interval at which route update timers record periodic updates, usually 30 seconds. A small random number of seconds is added each time the timer is reset to prevent conflict. Each route table entry has a related route time-out timer. When the route time-out timer expires, the path is marked as invalid but is still saved in the routing table, it is not cleared until the route clearing timer expires.