Shared Flashcard Set


Understanding OSPF Concepts
Computer Networking
11th Grade

Additional Computer Networking Flashcards




Comparing Dynamic Routing Protocol Features
■ Routing protocol: A set of messages, rules, and algorithms used by routers for the overall
purpose of learning routes. This process includes the exchange and analysis of routing information.
Each router chooses the best route to each subnet (path selection) and finally places
those best routes in its IP routing table. Examples include RIP, EIGRP, OSPF, and BGP.
■ Routed protocol and routable protocol: Both terms refer to a protocol that defines a
packet structure and logical addressing, allowing routers to forward or route the packets.
Routers forward packets defined by routed and routable protocols. Examples include IP
Version 4 (IPv4) and IP Version 6 (IPv6).
Routing Protocol Functions
1. Learn routing information about IP subnets from neighboring routers.
2. Advertise routing information about IP subnets to neighboring routers.
3. If more than one possible route exists to reach one subnet, pick the best route based on
a metric.
4. If the network topology changes—for example, a link fails—react by advertising that some
routes have failed and pick a new currently best route. (This process is called convergence.)
Interior and Exterior Routing Protocols
■ IGP: A routing protocol that was designed and intended for use inside a single autonomous
system (AS)
■ EGP: A routing protocol that was designed and intended for use between different
autonomous systems
IGP Routing Protocol Algorithms
■ Distance vector (sometimes called Bellman-Ford after its creators)
■ Advanced distance vector (sometimes called “balanced hybrid”)
■ Link-state
IP IGP Metrics
RIPv2 Hop count The number of routers (hops) between a router and the
destination subnet
OSPF Cost The sum of all interface cost settings for all links in a route,
with the cost defaulting to be based on interface bandwidth
EIGRP Composite of
bandwidth and delay
Calculated based on the route’s slowest link and the
cumulative delay associated with each interface in the route
OSPF 2 way state
■ The router received a Hello from the neighbor, with that router’s own RID listed as being
seen by the neighbor.
■ The router has checked all the parameters in the Hello received from the neighbor, with
no problems. The router is willing to become a neighbor.
■ If both routers reach a 2-way state with each other, it means that both routers meet all
OSPF configuration requirements to become neighbors. Effectively, at that point, they
are neighbors, and ready to exchange their LSDB with each other.
OSPF protocol
is open standard
Supporting users have an ad free experience!