How do you integrate OSPF and BGP with other routing protocols and technologies?

1 What is OSPF?

OSPF stands for Open Shortest Path First, and it is a link-state routing protocol. This means that it uses a complex algorithm to calculate the best path to each destination based on the state of the links, such as bandwidth, delay, and cost. OSPF is commonly used for internal routing within an autonomous system (AS), which is a group of networks under the same administrative control. OSPF is dynamic, scalable, and supports multiple areas and hierarchies.

2 What is BGP?

BGP stands for Border Gateway Protocol, and it is a path-vector routing protocol. This means that it uses a simple algorithm to choose the best path to each destination based on the attributes of the routes, such as length, origin, and preference. BGP is mainly used for external routing between different autonomous systems, and it is the protocol that runs the Internet. BGP is stable, flexible, and supports multiple policies and communities.

3 How do OSPF and BGP differ?

OSPF and BGP are designed for different scenarios and have various features. OSPF is an interior gateway protocol (IGP), while BGP is an exterior gateway protocol (EGP). OSPF uses a shortest-path-first algorithm, while BGP uses a path-vector algorithm. Additionally, OSPF relies on link-state information and has faster convergence, while BGP relies on route attributes and has slower convergence. Furthermore, OSPF has a lower overhead compared to BGP's higher overhead. Lastly, OSPF supports multiple areas and hierarchies, while BGP supports multiple policies and communities.

4 How do OSPF and BGP complement each other?

OSPF and BGP can work together to provide optimal routing in complex networks, complementing each other in various ways. OSPF can provide efficient and reliable internal routing within an AS, while BGP can provide flexible and scalable external routing between different ASes. Additionally, OSPF can distribute internal routes to BGP, while BGP can distribute external routes to OSPF. Moreover, OSPF can use BGP as a default route for unknown destinations, while BGP can use OSPF as a backup route for failed connections. Furthermore, OSPF can leverage BGP's attributes and policies to influence routing decisions, while BGP can leverage OSPF's link-state information to enhance route selection.

5 How do you integrate OSPF and BGP?

Integrating OSPF and BGP requires careful planning and configuration, as well as monitoring and troubleshooting. To begin, you must define the AS number and the AS boundary for each network. Then, configure the OSPF parameters and areas for each router within the AS. At the AS boundary, configure the BGP parameters and neighbors for each router. Redistribute the OSPF routes into BGP and vice versa, using filters and metrics to control the route exchange. Additionally, apply the appropriate BGP attributes and policies to influence the route selection and propagation. Finally, verify the OSPF and BGP operation and connectivity using various commands and tools.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?