ICR-1601
107
The supported dynamic routing protocols are described as follows:
RIP Scenario
The Routing Information Protocol (RIP) is one of
the oldest distance-vector routing protocols,
which employs the hop count as a routing metric.
RIP prevents routing loops by implementing
a limit on the number of hops allowed in a path
from the source to a destination. The maximum
number of hops allowed for RIP is 15. This hop
limit, however, also limits the size of networks
that RIP can support. A hop count of 16 is
considered an infinite distance, in other words
the route is considered unreachable. RIP
implements the split horizon, route poisoning and
hold-down mechanisms to prevent incorrect
routing information from being propagated.
OSPF Scenario
Open Shortest Path First (OSPF) is a routing
protocol that uses link state routing algorithm. It
is the most widely used interior gateway protocol
(IGP) in large enterprise networks. It gathers link
state information from available routers and
constructs a topology map of the network. The
topology is presented as a routing table which
routes datagrams based solely on the destination
IP address.
Network administrator can deploy OSPF gateway
in large enterprise network to get its routing table
from the enterprise backbone, and forward
routing information to other routers, which are
no linked to the enterprise backbone. Usually, an
OSPF network is subdivided into routing areas to
simplify administration and optimize traffic and
resource utilization.
As shown in the diagram, OSPF gateway
gathers routing information from the backbone
gateways in area 0, and will forward its routing
information to the routers in area 1 and area
2 which are not in the backbone.