This chapter covers the following topics, which you need to understand to pass the CCNP/CCDP/CCIP BSCI exam:
Understanding the fundamentals of redistribution
Identifying the issues with redistribution
Understanding the routing decisions that affect redistribution
Controlling routing updates during redistribution
Configuration commands to control routing updates in redistribution
Controlling routing updates with filtering
Verifying, maintaining, and troubleshooting the implementation of redistribution and filtering
The topics in this chapter deal with the traffic generated by routing updates in terms of both the network resources that they use and the information contained within them. This covers two different but related areas, redistribution and filtering. The network overhead involved in routing updates has already been dealt with in other chapters. It keeps recurring as a theme because all network traffic directly influences the network's capability to scale or to grow.
The information propagated through the network is complex when dealing with one routing protocol. When multiple protocols have to share information (through redistribution) so that the larger network can see every route available within the autonomous system, the information flow must be controlled and managed very closely with filtering and other solutions.
This chapter deals with the need for redistribution, which increases the network overhead, and filtering, which is used to reduce overhead. The chapter explains the design issues that might affect the configuration, followed by configuration examples of route redistribution and filtering.