RIPng Technology | Must see



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summary

RIP yes IETF An internal gateway protocol based on distance vector algorithm developed by the organization , With simple configuration 、 Easy to manage and operate , stay IPv4 Has been widely used in small and medium-sized networks .

With  IPv6 Network construction , The dynamic routing protocol is also required IPv6 Message forwarding provides accurate and effective routing information . therefore , IETF In keeping with RIP On the basis of advantages , in the light of IPv6 Network modification has taken shape RIPng.RIPng Mainly used in IPv6 The routing function is provided in the network , yes IPv6 An important routing protocol in network .

RIPng Technical realization

RIPng  In terms of working mechanism, it is in agreement with  RIP Basically the same , But in support of IPv6 Address format ,RIPng Yes RIP Some changes were made . Let's start with RIP Give a brief introduction , And then I'll talk about it in detail RIPng And RIP The differences and similarities .

RIP brief introduction

RIP Working mechanism

RIP adopt UDP Messages exchange routing information , The port number used is 520.RIP Use hops to measure the distance to the destination address , The number of hops is called a metric . stay RIP in , Router to the network directly connected to it The number of jumps in the complex is 0, The number of hops that can be reached through a router is 1, And so on . To limit the convergence time ,RIP Prescribed degree Measurement value 0~15 Integer between , Greater than or equal to 16 The number of hops is defined as infinity , The destination network or host is not reachable .RIP The start-up and operation process is as follows :

  • The router starts RIP after , The request message will be sent to the adjacent router . next , The router will continue to listen for messages from other routers RIP Request message or response message .

  • When the router sending the request receives the response message , The router will process the route update information in the response message and set its own route Update by table , At the same time, send trigger update message to adjacent routers , Notification route update information .

  • After the adjacent router receives the trigger update message , And send trigger update message to their respective adjacent routers . In a series of touches After the update broadcast , Each router can get and keep up-to-date routing information . In order to ensure the real-time and effectiveness of routing ,RIP By default, every 30 Send local routing tables to neighboring routers in seconds , At the same time, aging mechanism is used to aging the timeout routing .

RIP Version difference

RIP There are two versions :RIP-1 and RIP-2.

RIP-1 It's a classed routing protocol (Classful Routing Protocol), It only supports broadcasting protocol messages .RIP-1 Can't carry mask information , It can only recognize A、B、C Class, such as the routing of natural network segments , therefore RIP-1 Discontinuous subnets are not supported .

RIP-2 It is a classless routing protocol (Classless Routing Protocol), And RIP-1 comparison , It has the following advantages :

  • Support routing tags , In the routing strategy, the route can be flexibly controlled according to the routing label .

  • The message carries mask information , Support routing aggregation and  CIDR.

  • Support to specify the next hop , You can choose the best next hop address on the broadcast network .

  • Support multicast to send update message , Reduce resource consumption .

  • Add an authentication to the routing update message RTE(Route Entries, Routing table entries ) To support the verification of protocol messages Prove , And provide clear text verification and MD5 Verify two ways , Enhance security .

RIPng And RIP The differences and similarities

The difference between messages

1. The length of destination address and next hop address in routing information is different

RIP-2 The destination address and the next hop address of routing information in a message are only 32 The bit , and RIPng Are all 128 The bit .

2. Message length is different

RIP-2 There is a limit to the length of the message , Each message can only be carried at most 25 individual RTE, and RIPng For message length 、RTE There's no rule on the number of , The length of the message and the setting of the sending interface IPv6 MTU of .

3. The message format is different

RIP-2 The message structure is as follows chart 1 Shown , From the head (Header) And multiple RTE form .

chart 1 RIP-2 message

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RIPng The message structure is as follows chart 2 Shown . And RIP-2 equally ,RIPng Messages are also made by Header And multiple RTE form . And RIP-2 The difference is , stay RIPng There are two kinds of RTE, Namely :

  • Next jump RTE: Located in a group with the same next hop IPv6 Prefix RTE In front of , It defines the next hop of IPv6 The earth site

  • IPv6 Prefix RTE: At some next jump RTE Behind . The same next jump RTE There can be several different ones behind IPv6 Prefix RTE. It describes the RIPng Destination in routing table IPv6 Address 、 Routing tags 、 Prefix length and measure .

chart 2 RIPng message


image.png Next jump RTE The format is as follows chart 3 Shown , among ,IPv6 next hop address It means the next jump IPv6 Address

chart 3 Next jump RTE Format


image.pngIPv6 Prefix RTE The format is shown in the figure 4 Shown , The fields are explained as follows :

  • IPv6 prefix: Purpose IPv6 Prefix of address .

  • Route tag: Routing tags .

  • Prefix lenth:IPv6 Prefix length of address .

  • Metric: Metrics for routing .

chart 4 IPv6 Prefix RTE Format


image.png4, Messages are sent in different ways

RIP-2  Routing information can be periodically sent by broadcast or multicast according to user configuration ;RIPng Use multicast mode cycle Send routing information .

Security authentication is different

RIPng It does not provide authentication function , But by using  IPv6 The security mechanism is provided to ensure the legality of its own message . therefore , RIP-2 Authentication in the message RTE stay RIPng Cancelled in message .

Different from network layer protocol compatibility

RIP Not only in IP Running in the network , Can also be in IPX Running in the network ;RIPng Only in IPv6 Running in the network .

Comware Speed up the realization of RIP/RIPng The technical characteristics of routing convergence

When our equipment receives routes sent by multiple neighbors to the same destination but with different costs , It will reduce the cost of suboptimal routing Also kept locally . The effective mechanism of suboptimal routing is as follows :

  • When the optimal route is due to the link down Is deleted , Suboptimal routing will take effect immediately .

  • If the publisher of the optimal route stops updating the route , The device will start  Garbage-Collect Timer , At the end of the timer , If the suboptimal route is not revoked , Then the suboptimal route will take effect immediately . Suboptimal routing can take effect immediately after the primary route inhibition state ends , Instead of waiting for the router that publishes the suboptimal route to update the route again from . Saving suboptimal routes can speed up in many scenarios RIP/RIPng The routing convergence of . meanwhile , Whether the suboptimal route works depends on the main route Affected by inhibition , Routing loops can be avoided .

Typical networking applications

Such as chart 5 Shown , A school has built IPv6 The Internet , All hosts and routers in the school run IPv6 agreement . The school's network rules The module is smaller , choice RIPng Routing protocol can meet the needs of users , Any two nodes can communicate with each other , And lower the network Manual maintenance workload caused by topology changes .

chart 5 RIPng Typical application networking diagram


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