CCNA课件 2_距离矢量路由协议.ppt

Introducing Distance Vector Routing
Medium-Sized work Construction
Overview
Distance Vector Route
Routing Information Maintenance
How Routing Inconsistencies(Loops) Occur with Distance Vector Routing Protocols
Count to Infinity Prevention
Techniques to Eliminate Routing Loops
Implementation of Techniques to Eliminate Routing Loops
Summary
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.
Maintaining Routing Information
Inconsistent Routing Entries:Counting to Infinity and Routing Loops
Each node maintains the distance from itself to each possible work.
Counting to Infinity
Slow convergence produces inconsistent routing.
Counting to Infinity (Cont.)
Router C concludes that the best path to network is through router B.
Counting to Infinity (Cont.)
Router A updates its table to reflect the new but erroneous hop count.
Counting to Infinity (Cont.)
The hop count work counts to infinity.