路由原理基础-精品.ppt

路由原理基础-精品
Static Route
Uses a route that a network administrator enters into the router manually
Dynamic Route
Use路由原理基础-精品
Static Route
Uses a route that a network administrator enters into the router manually
Dynamic Route
Uses a route that a network routing protocol adjusts automatically for topology or traffic changes
Static vs. Dynamic Routes
What Is a Dynamic Routing Protocol?
Routing protocols are used between routers to determine paths to remote networks and maintain those networks in the routing tables.
After the path is determined, a router can route a routed protocol to the learned networks.
An autonomous system is a collection of networks within a common administrative domain.
Interior gateway protocols operate within an autonomous system.
Exterior gateway protocols connect different autonomous systems.
Autonomous Systems: Interior and Exterior Routing Protocols
Classes of Routing Protocols
Selecting the Best Route Using Metrics
Administrative Distance: Ranking Routing Sources
Routers choose the routing source with the best administrative distance:
OSPF has an administrative distance of 110.
EIGRP has an administrative distance of 90.
Distance Vector Routing Protocols
Routers pass periodic copies of their routing table to neighboring routers and accumulate distance vectors.
Sources of Information and Discovering Routes
Routers discover the best path to destinations from each neighbor.
Counting to Infinity (Cont.)
The hop count for network counts to infinity.
Solution to Counting to Infinity:Defining a Maximum
A limit is set on the number of hops to prevent infinite loops.
Routing Loops
Packets for network bounce (loop) between routers B and C.
Solution to Routing Loops: Split Horizon
It is never useful to send information about a route back in the direction from which the original information came.
Solution to Routing Loops:Route Poisoning and Poison Reverse
Routers advertise the distance