How can you design BGP routing policies that accommodate growth?

1 Understand your network objectives

Before you start designing your BGP routing policies, you need to have a clear understanding of your network objectives and requirements. What are your business goals, your traffic patterns, your service level agreements, your security policies, and your budget constraints? How do you want to balance between cost, performance, reliability, and flexibility? How do you want to interact with your BGP peers, customers, and providers? These questions will help you define your network architecture, your AS number, your peering strategy, and your routing policy framework.

3 Use route attributes and communities

Another important aspect of designing BGP routing policies is to use route attributes and communities to influence the route selection and propagation process. Route attributes are parameters that describe the characteristics and preferences of a route, such as origin, AS path, local preference, MED, weight, and next hop. Communities are tags that can be attached to routes to indicate their membership or status, such as customer, peer, backup, or no-export. You can use route attributes and communities to manipulate the BGP decision algorithm, prioritize certain routes over others, implement traffic engineering, and enforce policy compliance.

4 Use route reflectors and confederations

A common problem that arises when designing BGP routing policies is the scalability of the internal BGP (iBGP) sessions. iBGP is the protocol that runs between the routers within the same AS, and it requires a full mesh topology, which means that every router has to establish a session with every other router. This can lead to a large number of sessions and overhead, especially for large ASes. To overcome this problem, you can use route reflectors and confederations. Route reflectors are routers that act as proxies for other routers, and they can reflect the routes they receive from one iBGP peer to another without modifying them. Confederations are sub-divisions of an AS, and they can reduce the number of iBGP sessions by treating each sub-AS as an external BGP (eBGP) peer.

5 Use policy templates and automation

The final tip for designing BGP routing policies that can accommodate growth is to use policy templates and automation tools to simplify and streamline the policy creation and maintenance process. Policy templates are predefined sets of rules and parameters that can be applied to multiple routers or peers, and they can help you standardize and organize your policies, avoid errors and inconsistencies, and save time and effort. Automation tools are software or scripts that can automate the policy deployment and verification, and they can help you reduce the human intervention, increase the accuracy and speed, and enhance the security and reliability of your policies.

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?