Operation Manual – Routing Protocol
H3C S3600 Series Ethernet Switches-Release 1510 Chapter 3
RIP Configuration
3-2
z Routing time: Time elapsed after the routing entry is updated last time. This time
is reset to 0 whenever the routing entry is updated.
III. RIP timers
As defined in RFC 1058, RIP is controlled by three timers: Period update, Timeout,
and Garbage-collection.
z Period update timer: This timer is used to periodically trigger routing information
update so that the router can send all RIP routes to all the neighbors.
z Timeout timer: If a RIP route is not updated (that is, the switch does not receive
any routing update packet from the neighbor) within the timeout time of this timer,
the route is considered unreachable.
z Garbage-collection timer: An unreachable route will be completely deleted from
the routing table if no update packet for the route is received from the neighbor
before this timer times out.
3.1.2 RIP Startup and Operation
The whole process of RIP startup and operation is as follows:
z Once RIP is enabled on a router, the router broadcasts or multicasts a request
packet to its neighbors. Upon receiving the packet, each neighbor running RIP
answers a response packet containing its routing table information.
z When this router receives a response packet, it modifies its local routing table
and sends an update triggering packet to the neighbor. Upon receiving the
update triggering packet, the neighbor sends the packet to all its neighbors. After
a series of update triggering processes, each router can get and keep the
updated routing information.
z By default, RIP sends its routing table to its neighbors every 30 seconds. Upon
receiving the packets, the neighbors maintain their own routing tables and select
optimal routes, and then advertise update information to their respective
neighbors so as to make the updated routes known globally. Furthermore, RIP
uses the timeout mechanism to handle the timeout routes to ensure real-time
and valid routes.
RIP is commonly used by most IP router suppliers. It can be used in most campus
networks and the regional networks that are simple and less disperse. For larger and
more complicated networks, RIP is not recommended.
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