User`s manual

The Routing Information Protocol (RIP)
The Routing Information Protocol (RIP) is an Interior Gateway Protocol (IGP) used mainly on
moderately-sized networks. RIP uses a vector-distance routing method that keeps a table of all known IP
address destinations (the vector) and the number of hops to reach them (the distance).
Configuring RIP
To configure RIP settings using either the Command Line or Web version of the BitStorm L3S Series Device
Manager, see:
Configuring RIP - Command Line version●
Configuring RIP - Web version●
For an overview of RIP and the settings you need to make in configuring RIP, see Background below. For
complete details, refer to RFC 1058 and RFC 1723, which define RIP versions 1 and 2.
Background
RIP routers choose the network path that goes through the minimum number of routers, or hops. RIP supports a
maximum hop count of 15. Destinations 16 hops or more away are considered unreachable.
The hop count is also referred to as the cost or metric. IP address prefixes belonging to directly connected
network segments appear in the routing table with a cost of 1.
RIP routers exchange routing information with other RIP routers by broadcasting updates at regular, pre-set
intervals. These updates include a copy of a router's entire routing table, the list of all known destination prefixes
and their metrics.
When it receives a RIP update from a neighbor, a RIP router decides whether or not to update its own routing
table.
Triggered updates
When its routing table does change, the RIP router can be set to broadcast updates immediately without waiting
for the preset update timer whose default is 30 seconds. These are called triggered updates. Triggered updates
advertise only those prefixes whose cost has changed. For example:
an interface has been enabled
●
an interface has gone down●
a RIP update from a neighbor has modified the routing table●
a routing table entry has timed out●
Because a RIP router expects to receive routing updates continually, it eventually gives up on the next-hop
router after it fails to receive updates. After 90 seconds pass without an update from the next hop router, the
router moves the next hop to any neighboring router that advertises a path of equal cost. After 180 seconds, the
entry is declared unreachable.
RIP can be enabled on any routing interface on your Switch. When you configure RIP, the Switch uses this
protocol to determine the best path to another network. It does this by sending and receiving updated routing
information from other RIP routers.
It compiles this information in a routing table of every network destination it has learned. This table includes:
the IP address of the destination network
●
the metric, or number of hops, to the destination network●
the IP address of the next router●
a timer indicating how much time has elapsed since an entry was last updated●
Under RIP, routers are either active or silent. Active routers advertise their routes to others. Silent routers can
only listen. They cannot send routing information to others. Both active and silent RIP routers listen to all
messages and update their routing tables accordingly.
Once a RIP-enabled routing interface learns a route, it keeps it until it learns a better one. If the first port to
advertise a route fails, all listeners must timeout all routes they learned via RIP from all other RIP ports. A route
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