SGS-6341-Series User Manual

packets by packet
s broadcast, subnet mask and authentication is not supported. Some fields
in the RIP-I packets are not used and are required to be all 0’s; for this reason, such all 0's
fields should be checked when using RIP-I, the RIP-I packets should be discarded if such
fields are non-zero. RIP-II is a more improved version than RIP-I. RIP-II sends route update
packets by multicast packets (multicast address is 224.0.0.9). Subnet mask field and RIP
authentication filed (simple plaintext password and MD5 password authentication are
supported), and support variable length subnet mask. RIP-II used some of the zero field of
RIP-I and require no zero field verification. Switch sends RIP-II packets in multicast by default,
both RIP-I and RIP-II packets will be accepted.
Each Layer 3 switch running RIP has a route database, which contains all route entries for
reachable destination, and route table is built based on this database. When a RIP Layer 3
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 Layer 3 switch is quite large, causing degraded network performance.
Besides the above mentioned, RIP protocol allows route information discovered by the other
routing protocols to be introduced to the route table.
The operation of RIP protocol is shown below:
1． Enable RIP. The switch sends request packets to the neighbor Layer 3 switches
by broadcasting; on receiving the request, the neighbor devices reply with the
packets containing their local routing information.
2． The Layer 3 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 packet, the neighbor lay3
switches send triggered update packets to their neighbor lay3 switches. After a
sequence of triggered update packet broadcast, all Layer 3 switches get and
maintain the latest route information.
In addition, RIP Layer 3 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, RIP 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outdated route, that is, if a switch does not receive regular update packets from a neighbor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 (holddown timer interval), it will delete that route.
26.4.2 RIP Configuration Task List
1. Enable RIP (required)
(1) Enable/disable RIP module.
(2) Enable interface to send/receive RIP packets
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User’s Manual of SGS-6341 series