Allied Telesis AT-S63 - Manual (Page 554)

Chapter 32: Internet Protocol Version 4 Packet Routing
554 Section VII: Internet Protocol Routing
Routing
Information
Protocol (RIP)
A switch can automatically learn routes to remote destinations by sharing
the contents of its routing table with its neighboring routers in the network
with the Routing Information Protocol (RIP) versions 1 and 2.
RIP is a fairly simple distance vector routing protocol that defines networks
based in how many hops they are from the switch, just as with static
routes. Once a network is more than fifteen hops away (one hop is one
link), it is considered as unreachable and is not included in the routing
table.
RIP version 2 permits the addition of subnet masks and next hop
information in RIP updates. This allows the use of different sized subnet
masks on different subnets within the same network.
RIP broadcasts are automatically activated when the protocol is added to
a routing interface on the switch. An interface sends RIP packets to the
RIP multicast address 224.0.0.9 when sending version 2 packets or uses
the broadcast address when sending out version 1 packets.
A route is propagated by RIP if its status at the physical level is active. An
active route has at least active one port in the VLAN. RIP does not
propagate an inactive route where there are no active ports in the VLAN.
RIP can be added to a maximum of 100 interfaces on a switch and the
route table can store up to 1024 dynamic routes.
Since the interfaces on a switch can route packets among the local
subnets without the presence of RIP or static routes, the routing protocol is
only necessary if the switch is to learn remote destinations by sharing the
switch’s routing table with the neighboring routers, and you choose not to
specify the routes manually with static routes.
You add RIP to the routing interfaces where there are neighboring routers
to remote destinations. You do not need to add RIP to interfaces where
there are no neighboring routers.
A route learned by RIP is immediately added to the routing table, where it
becomes available to all the interfaces on the switch.
The RIP implementation on the AT-9400 Series switch supports split
horizon. This feature prevents the switch from sending out or advertising a
dynamic route on the same interface where it was learned. The split
horizon feature is activated on an interface as soon as you add RIP. It
cannot be disabled.
When you add RIP to an interface, you can specify the type of RIP packets
the routing protocol is to send and receive. An AT-9400 Series switch can
send either version 1 or 2 packets and accept either or both versions.