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gateway routes leaned from that gateway. There are two split horizon methods: “simple
split horizon” and “poison reverse split horizon”. Simple split horizon deletes from the
route to be sent to the neighbor gateways the routes learned from the neighbor gateways;
poison reverse split horizon not only deletes the abovementioned routes, but set the
costs of those routes to infinite. “Triggering update” mechanism defines whenever route
metric changed by the gateway, the gateway advertise the update packets immediately
other than wait for the 30 sec timer.
So far the RIPng protocol has got only one version----Version1: RIPng protocol is
introduced in RFC 2080. RIPng transmits updating data packet by multicast data packet
(multicast address FF02::9)
Each layer3 switch running RIPng has a route database, which contains all route
entries for reachable destination, and route table is built based on this database. When a
RIPng layer3 switch sent route update packets to its neighbor devices, the complete
route table is included in the packets. Therefore, in a large network, routing data to be
transferred and processed for each layer3 switch is quite large, causing degraded
network performance.
Besides the above mentioned, RIPng protocol allows IPv6 route information
discovered by the other routing protocols to be introduced to the route table.
The operation of RIPng protocol is shown below:
Enable RIPng The switch sends request packets to the neighbor layer3 switches by
broadcasting; on receiving the request, the neighbor devices reply with the packets
containing their local routing information.
The Layer3 switch modifies its local route table on receiving the reply packets and sends
triggered update packets to the neighbor devices to advertise route update information.
On receiving the triggered update package, the neighbor lay3 switches send triggered
update packages to their neighbor lay3 switches. After a sequence of triggered update
package broadcast, all layer3 switches get and maintain the latest route information.
In addition, RIPng layer3 switches will advertise its local route table to their neighbor
devices every 30 seconds. On receiving the packets, neighbor devices maintain their
local route table, select the best route and advertise the updated information to their own
neighbor devices, so that the updated routes are globally valid. Moreover, RIPng uses a
timeout mechanism for outdated route, that is, if a switch does not receive regular update
packets from a neighbor within a certain interval (invalid timer interval), it considers the
route from that neighbor invalid, after holding the route fro a certain interval (garbage
collect timer interval), it will delete that route.
As a result of continuous development of IPv6 network, it has the network
environment of nonsupport IPv6 sometimes, so it needs to do the IPv6 operation by
tunnel. Therefore, our RIPng supports configuration on configure tunnel, and passes
