Customers connect to the Internet by using service providers to enable applications such as intranet connectivity with VPNs, extranet connectivity with suppliers, and other Internet applications. When you plan network connectivity to an ISP, you as a network designer must give careful consideration to the various aspects of the connectivity. These aspects include physical connection types, the redundancy that the chosen connection method provides, IP addressing requirements, and AS numbering considerations if the network design will meet both business and technical requirements of the applications that are planned for the network. In this course, you will learn solutions for connecting customer networks to service providers. You will also learn customer network redundancy requirements, routing requirements, IP addressing requirements, and AS numbering requirements.

When a customer can connect to the Internet through either a single connection to a service provider or through multiple connections to the same ISP, static routing is the simplest routing approach to implement between the customer and provider. When network administrators are implementing customer-to-provider connectivity with static routes, knowledge of static routing implementation guidelines will aid in successfully deploying static routing network configurations.

When multiple connections to the same service provider is the only way that a customer can connect to the Internet, the connections must be correctly configured. They must ensure proper interaction between the customer and the service provider network. You must understand how to configure routing protocols so that customer backup or load-balancing requirements are met. In this course, you will learn about the use of multiple connections between a customer and a single ISP for backup and load-sharing purposes.

A customer that requires the maximum redundancy in its network design should implement a multihomed strategy that uses multiple service providers. This configuration requires specific considerations to be implemented properly. Addressing and AS number selection are important considerations that affect the network implementation. Routing protocols must be configured correctly so that customer backup or load-sharing requirements are met. In this course, you will learn about multiple connections between a customer and multiple service providers for backup and load-sharing purposes, including the BGP characteristics that are used to configure such connectivity. You will also learn about address selection, private AS number translation, and configuration of the network to support either backup links or load sharing.

All service providers are concerned about properly scaling IP addressing, IGPs, and BGP. It can be the difference between a successful and a problematic BGP implementation. Service provider networks are complex and must meet the administrative policy and routing demands of the internal network, different customers, and other providers. Proper scaling is crucial to the success of the network. Interactions between IGPs and the BGP can be quite complex, specifically when you support internal routing, customer connectivity, and transit traffic (and the administrative policies that match). Furthermore, the large number of prefixes that are required to support full Internet routing requires administrators to fully characterize IGP and BGP interactions for internal networks and customers alike. This course discusses network scalability concerns common to large, complex service provider networks. This course includes a description of a typical ISP network and discussion of the propagation of internal and customer routing information. This course also describes scaling considerations for IGPs and BGP, and scaling of IP addressing in service provider networks.